Human evolution and exploration of the world were shaped by a hunger for tasty food – “a quest for deliciousness” – according to two leading academics.
Ancient humans who had the ability to smell and desire more complex aromas, and enjoy food and drink with a sour taste, gained evolutionary advantages over their less-discerning rivals, argue the authors of a new book about the part played by flavour in our development.
Some of the most significant inventions early humans made, such as stone tools and the controlled use of fire, were also partly driven by their pursuit of flavour and a preference for food they considered delicious, according to the new hypothesis.
“This key moment when we decide whether or not to use fire has, at its core, just the tastiness of food and the pleasure it provides. That is the moment in which our ancestors confront a choice between cooking things and not cooking things,” said Rob Dunn, a professor of applied ecology at North Carolina State University. “And they chose flavour.”
Cooked food tasted more delicious than uncooked food – and that’s why we opted to continue cooking it, he says: not just because, as academics have argued, cooked roots and meat were easier and safer to digest, and rewarded us with more calories.
Some scientists think the controlled use of fire, which was probably adopted a million years ago, was central to human evolution and helped us to evolve bigger brains.
“Having a big brain becomes less costly when you free up more calories from your food by cooking it,” said Dunn, who co-wrote Delicious: The Evolution of Flavour and How it Made Us Human with Monica Sanchez, a medical anthropologist.
However, accessing more calories was not the primary reason our ancestors decided to cook food. “Scientists often focus on what the eventual benefit is, rather than the immediate mechanism that allowed our ancestors to make the choice. We made the choice because of deliciousness. And then the eventual benefit was more calories and fewer pathogens.”
Human ancestors who preferred the taste of cooked meat over raw meat began to enjoy an evolutionary advantage over others. “In general, flavour rewards us for eating the things we’ve needed to eat in the past,” said Dunn.
In particular, people who evolved a preference for complex aromas are likely to have developed an evolutionary advantage, because the smell of cooked meat, for example, is much more complex than that of raw meat. “Meat goes from having tens of aromas to having hundreds of different aroma compounds,” said Dunn.
Prehistoric woolly mammoth hunters. Photograph: North Wind Picture Archives/Alamy
This predilection for more complex aromas made early humans more likely to turn their noses up at old, rotten meat, which often has “really simple smells”. “They would have been less likely to eat that food,” said Dunn. “Retronasal olfaction is a super-important part of our flavour system.”
The legacy of humanity’s remarkable preference for food which has a multitude of aroma compounds is reflected in “high food culture” today, Dunn says. “It’s a food culture that really caters for our ability to appreciate these complexities of aroma. We’ve made this very expensive kind of cuisine that somehow fits into our ancient sensory ability.”
Similarly, our proclivity for sour-tasting food and fermented beverages like beer and wine may stem from the evolutionary advantage that eating sour food and drink gave our ancestors.
“Most mammals have sour taste receptors,” said Dunn. “But in almost all of them, with very few exceptions, the sour taste is aversive – so most primates and other mammals, in general, will, if they taste something sour, spit it out. They don’t like it.”
Humans are among the few species that like sour, he says, another notable exception being pigs.
At some point, he thinks, humans’ and pigs’ sour taste receptors evolved to reward them if they found and ate decomposing food that tasted sour, especially if it also tasted a little sweet – because that is how acidic bacteria tastes. And that, in turn, is a sign that the food is fermenting, not putrefying.
“The acid produced by the bacteria kills off the pathogens in the rotten food. So we think that the sour taste on our tongue, and the way we appreciate it, actually may have served our ancestors as a kind of pH strip to know which of these fermented foods was safe,” said Dunn.
Human ancestors who were able to accurately identify rotting food that was actually fermenting, and therefore OK to eat, would have had an evolutionary advantage over others, he argues. If they also figured out how to safely ferment food to eat over winter, they further increased their food supply.
The negative consequence of this is that fermented, alcoholic fruit juice, a sort of “proto wine”, would also have tasted good – and that probably led to horrific hangovers.
“At some point, our ancestors evolved a version of the gene that produces the enzyme that breaks down alcohol in our bodies, which is 40 times faster than that of other primates,” added Dunn. “And so that really made our ancestors much more able to get the calories out of these fermented drinks, and it would also probably have lessened the extent to which they had hangovers every day from drinking.”
Flavour also drove humanity to innovate and explore, Dunn says. He thinks one reason our ancestors were inspired to begin using tools was to get hold of otherwise inaccessible food that tasted delicious: “If you look at what chimpanzees use tools to get, it’s almost always really delicious things, like honey.”
Having a portfolio of tools that they could use to find tasty things to eatgave our ancestors the confidence to explore new environments, knowing they would be able to find food, whatever the season threw at them. “It really allows our ancestors to move out into the world and do new things.”
Still Life with a Turkey Pie, by Pieter Claesz, 1627. Photograph: FineArt/Alamy
Stone tools in particular “fast-forward” the ability of humans to find delicious food. “Once they can hunt, using spears, they have access to this whole world of foods that were not available to them before.”
At this point, Dunn thinks humanity’s pursuit of tasty food started to have terrible consequences for other species. “We know that humans around the world hunted species to extinction, once they figured out how to hunt really effectively.”
Dunn strongly suspects that the mammals that first went extinct were the most delicious ones. “From what we were able to reconstruct, it looks like the mammoths, mastodons and giant sloths all would have been unusually tasty.”
To replicate the eating habits of prehistoric humans, the book, published later this month, details how one scientist dropped a horse who had just died into a pond and assessed how it fermented over time. “He would sample some meat to see if it was safe to eat. He described it as delicious – a little bit like a blue cheese,” said Dunn.
The head of Jeep’s owner said he is open to dropping the Cherokee name from vehicles after recent criticism from the Native American tribe’s leader.
Carlos Tavares,
chief executive officer of the recently formed
Stellantis
STLA -2.71%
NV, said the company was engaged in dialogue with the Cherokee Nation over its use of the name. Jeep has two models, the Cherokee compact sport-utility vehicle and larger Grand Cherokee, that it sells in the U.S. and beyond.
Asked in an interview if he would be willing to change the Jeep Cherokee’s name if pushed to do so, Mr. Tavares said, “We are ready to go to any point, up to the point where we decide with the appropriate people and with no intermediaries.”
“At this stage, I don’t know if there is a real problem. But if there is one, well, of course we will solve it,” Mr. Tavares said, adding that he wasn’t personally involved in the talks.
Debate over the Cherokee name is among the issues facing Mr. Tavares, who took control of Stellantis when it was formed earlier this year from the merger of Fiat Chrysler Automobiles NV and Peugeot-maker PSA. In the interview Wednesday, Mr. Tavares also discussed whether to cut down on the company’s 14 brands, making Fiat plants more competitive and his plan to stick with China.
Jeep has two models, the Cherokee compact SUV and larger Grand Cherokee, that it sells in the U.S. and beyond.
Photo:
FCA/TNS/Abaca Press/Reuters
The Cherokee Nation is the largest Native American tribe in the U.S., with some 370,000 members, and Jeep has sold millions of vehicles named after it. The auto brand extended its use of the Cherokee name to a compact SUV, a smaller version of the Grand Cherokee, in 2013.
The leader of the Cherokee Nation recently said he would like to see Jeep stop using his tribe’s name on its SUVs.
Chuck Hoskin Jr.,
principal chief of the Cherokee Nation, said that he believed Jeep had good intentions but that “it does not honor us by having our name plastered on the side of a car,” according to a statement first released to Car and Driver last week.
“The Cherokee Nation has an open dialogue with Stellantis leadership, and look forward to ongoing discussions,” a spokesman for the tribe said Wednesday. “We appreciate Stellantis’ reaching out and thoughtful approach on this.”
“
‘It does not honor us by having our name plastered on the side of a car.’ ”
— Chuck Hoskin Jr., principal chief of the Cherokee Nation
Mr. Tavares’s remarks come in the wake of a broad reckoning over racial and social injustice in the U.S. that was sparked by the police killing of
George Floyd,
an unarmed Black man, in Minneapolis over Memorial Day weekend last year. In December, the Cleveland Indians decided to drop the baseball team’s longtime nickname after fans and Native American groups criticized it as racist. The Washington Football Team of the NFL has dropped a name that had been seen as a racial slur.
The Jeep Cherokee and Grand Cherokee SUVs are among the brand’s bestsellers in the U.S., accounting for 43% of Jeep’s sales in its largest market, according to company figures. Stellantis is rolling out a long-awaited redesign of the Grand Cherokee later this year.
Mr. Tavares said the auto industry’s practice of naming cars after Native American tribes was a sign of respect.
“I don’t see anything that would be negative here. I think it’s just a matter of expressing our creative passion, our artistic capabilities,” Mr. Tavares said.
The Jeep brand sits alongside profit-drivers like Ram in the U.S. and Peugeot in Europe. But the company’s sprawling portfolio of 14 brands also includes some that will need to prove their worth, Mr. Tavares said.
Mr. Tavares said he has asked each of his brand chiefs to work on a 10-year plan to develop more long-term visibility on product planning.
“I’m saying, ‘Look guys, I’m going to give you a chance. You need to convince me—you, the brand CEO—that you have a vision,’” Mr. Tavares said.
After several turnaround efforts, Fiat Chrysler’s Alfa Romeo and Maserati brands have failed to mount meaningful comebacks in recent years. The Fiat brand struggles with aging models and weak sales, which has caused an overcapacity problem in the company’s Italian factories.
Even the storied Chrysler brand has waned in recent years, now selling only three models compared with the six it carried a decade ago. The brand’s U.S. sales have also slid to one-third their volume in 2015, according to company figures.
On the PSA side, the DS brand—which focuses on high-end sedans and SUVs—grew market share last year but continues to lag far behind some of its German competitors.
“After we give them a chance to fail, we need to be also fair,” Mr. Tavares said. “If the rest of the company is doing the right things and there is one part of the company that is pulling everybody down, we’ll have to take that into consideration.”
The Portuguese executive built his reputation in the automotive industry as a turnaround expert. Peugeot was bleeding money when it hired Mr. Tavares in 2013. Since then the French car maker has gone from losing 5 billion euros, equivalent to about $6 billion, in 2012 to becoming one of the most profitable mass-market car makers in the industry. Last year it reported a net profit of €2.17 billion, or roughly $2.62 billion, with an adjusted operating margin of 7.1% in its core automotive business.
This time, Mr. Tavares has a longer to-do list, including integrating the two companies’ European businesses and stemming losses in China.
In Europe, Mr. Tavares has been visiting Fiat Chrysler factories—including an Alfa Romeo facility 80 miles south of Rome—and encouraging them to benchmark their performance against PSA plants. Additionally, employees from Fiat Chrysler’s Fiat factory in Mirafiori, Italy, visited PSA’s Citroën’s plant in Madrid, and Mr. Tavares said they were surprised by the nonlabor cost savings they observed.
The auto executive said the new company could reach its cost-saving goals in Europe without closing factories.
Asked what lessons he had learned from the chip shortage that has idled car plants across the world, Mr. Tavares said large suppliers didn’t relay signals they were receiving about the looming crisis. “We were not protected,” he said. “That’s a clear lesson learned.”
Chinese regulators are taking a close look at Tesla operations after recent videos on social media appear to show a Model 3 battery fire and malfunctioning vehicles. WSJ explains how possible quality issues with Tesla cars could threaten the EV-maker’s meteoric rise. Photo Illustration: Michelle Inez Simon
Mr. Tavares said the industrywide shift toward electrification would continue to rely on government subsidies and other financial incentives for buyers until auto makers figure out how to lower production costs over the next few years.
“If we propose electric vehicles which are extremely efficient but nobody can buy because they are costly, what’s the point from an environmental perspective?” he said.
In China, the combined sales of Peugeot and Fiat Chrysler accounted for less than 1% of a market that sold 20 million vehicles last year, according to industry data. Fiat Chrysler has long struggled to turn a profit in the world’s largest automotive market, while the French car maker sold only 45,965 vehicles in China last year, continuing a rapid multiyear decline.
Mr. Tavares said Stellantis isn’t considering exiting China, removing an option that he said was still on the table when the company started trading in New York at the start of this year.
“We cannot be away from the biggest market in the world,” he said.
Write to Nick Kostov at Nick.Kostov@wsj.com and Nora Naughton at Nora.Naughton@wsj.com
ROME—Pope Francis accepted the resignation of Cardinal Robert Sarah as head of the Vatican’s office for liturgy, removing an outspoken conservative and possible future pope from the ranks of Vatican leadership.
The Holy See Press Office announced Saturday that Cardinal Sarah had stepped down. No successor has been named.
The cardinal submitted his resignation as required by church law when he turned 75 on June 15 of last year. But the pope frequently lets cardinals serve two or three years past that age, though not past 80.
In accepting Cardinal Sarah’s resignation, the pope has removed a subordinate out of step with his approach to liturgy, homosexuality and relations with the Muslim world. The cardinal is a hero to many conservative Catholics, some of whom see him as a future pontiff. He will still be able to vote in a conclave to elect a pope until he turns 80.
Last year, the cardinal raised controversy with a book widely interpreted as an attempt to influence Pope Francis’ decision on whether to allow the ordination of married men as priests. The episode led to embarrassment for the cardinal when retired Pope Benedict XVI asked to have his name removed as the book’s co-author.
The record-fast creation of Covid-19 vaccines was a triumph. So why is it taking so long to vaccinate Americans?
The answer starts with tens of millions of Covid-19 vaccine doses that sat unused in medical freezers across the U.S. in the early weeks of the rollout.
In the launch, the federal government set aside far more doses for nursing homes than the facilities needed. A fragmented chain of communication between federal authorities dispatching doses and the local sites ultimately injecting them left the vaccinators in the dark about how many patients they could schedule. Worried about limited supplies, some hospitals and health departments held back doses to make sure they had enough to administer second shots for staff or to meet appointments, creating a bottleneck to the outflow.
Vaccinations are now picking up. But early stumbles might extend the pandemic, and leave more people without protection. Health officials say the new coronavirus variants that appear to spread more easily make the distribution of vaccines more urgent.
The Trump administration invested heavily in rapid vaccine development, but it left the last mile of getting shots into arms to states and localities. That approach resulted in multiple, sometimes contradictory systems, and failed to ensure local sites had information about vaccine shipments that they needed to quickly administer shots.
Four people have died of Ebola in Guinea in the first resurgence of the disease in five years, the health minister said on Saturday.
Remy Lamah told AFP officials were “really concerned” about the deaths, the first since a 2013-16 epidemic – which began in Guinea – left 11,300 dead across the region.
One of the latest victims in Guinea was a nurse who fell ill in late January and was buried on 1 February, National Health Security Agency head Sakoba Keita told local media. “Among those who took part in the burial, eight people showed symptoms: diarrhoea, vomiting and bleeding,” he said. “Three of them died and four others are in hospital.”
The four deaths from Ebola hemorrhagic fever occurred in the south-east region of Nzerekore, he said.
Keita also told local media that one patient had “escaped” but had been found and hospitalised in the capital Conakry. He confirmed the comments to AFP without giving further detail.
The World Health Organization has eyed each new outbreak since 2016 with great concern, treating the most recent one in the Democratic Republic of Congo (DRC) as an international health emergency.
DRC has faced several outbreaks of the illness, with the WHO on Thursday confirming a resurgence three months after authorities declared the end of the country’s latest outbreak.
The country had declared the six-month epidemic over in November. It was the country’s 11th Ebola outbreak, claiming 55 lives out of 130 cases.
The widespread use of vaccinations, which were administered to more than 40,000 people, helped curb the disease.
The 2013-16 outbreak sped up the development of a vaccine against Ebola, with a global emergency stockpile of 500,000 doses planned to respond quickly to future outbreaks, the vaccine alliance Gavi said in January.
When America’s amusement parks and baseball stadiums no longer must serve as COVID-19 mass vaccination sites, some investors believe that households pocketing pandemic financial aid from the government might start to splurge.
While a consumer splurge could initially boost the parts of the economy devastated by the pandemic, a bigger concern for investors is that a sustained spending spree also could cause prices for goods and services to rise dramatically, dent financial asset values, and ultimately raise the cost of living for everyone.
“I don’t think inflation is dead,” said Matt Stucky, equity portfolio manager at Northwestern Mutual Wealth Management Company. “The desire by key policy makers is to have it, and it’s the strongest it’s ever been. You will see rising inflation.”
Wall Street investors and analysts have become fixated in recent weeks on the potential for the Biden Administration’s planned $1.9 trillion fiscal stimulus package that targets relief to hard-hit households to cause inflation to spiral out of control.
Economists at Oxford Economics said on Friday they expect to see the “longest inflation stretch above 2% since before the financial crisis, but it’s unlikely to sustainably breach 3%.”
Severe inflation can hurt businesses by ratcheting up costs, pinching profits and causing stock prices to fall. The value of savings and bonds also can be chipped away by high inflation over time.
Another worry among investors is that runaway inflation, which took hold in the late 1970s and pushed 30-year mortgage rates to near 18%, could force the Federal Reserve to taper its $120 billion per month bond purchase program or to raise its benchmark interest rate above the current 0% to 0.25% target sooner than expected and spook markets.
At the same time, it’s not far-fetched to argue that some financial assets already have been inflated by the Fed’s pedal-to-the-metal policy of low rates and an easy flow of credit, and might be due for some cooling off.
U.S. stocks, including the Dow Jones Industrial Average
DJIA,
+0.09%,
S&P 500 index
SPX,
+0.47%
and Nasdaq Composite
COMP,
+0.50%
closed on Friday at all-time highs, while debt-laden companies can now borrow in the corporate “junk” bond, or speculative-grade, market at record low rates of about 4%.
Read: Stock market stoked by stimulus hopes — what investors are counting on
In addition to rallying stocks and bonds, home prices in the U.S. also have gone through the roof during the pandemic, despite the U.S. still needing to recoup almost as many jobs from the COVID-19 crisis as during the worst of the global financial crisis in 2008.
This chart shows that jobs lost to the pandemic remain near to levels seen in the aftermath of that last crisis.
Job losses need to be tamed
LPL Research, Bureau of Labor Statistics
Fed Chairman Jerome Powell said Wednesday that he doesn’t expect a “large or sustained” outbreak of inflation, while also stressing that the central bank remains focused on recouping lost jobs during the pandemic, as the U.S. looks to makes serious headway in its vaccination program by late July.
Treasury Secretary Janet Yellen on Friday reiterated a call on Friday that the time for more, big fiscal stimulus is now.
“Broadly, the guide is, does it cost me more to live a year from now than a year prior,” Jeff Klingelhofer, co-head of investments at Thornburg Investment Management, said about inflation in an interview with MarketWatch.
“I think what we need to watch is wage inflation,” he said, adding that higher wages for upper income earners were mostly flat for much of the past decade. Also, many lower-wage households hardest hit by the pandemic have been left out of the past decade’s climb in financial asset prices and home values, he said.
“For the folks who haven’t taken that ride, it feels like a perpetuation of inequality that’s played out for some time,” he said, adding that the “only way to get broad inflation is with a broad overheating of the economy. We have the exact opposite. The bottom third are no where near overheating.”
Klingelhofer said it’s probably also a mistake to watch benchmark 10-year Treasury yields for signs that the economy is overheating and for inflation since, “it’s not a proxy for inflation. It’s just a proxy for how the Fed might react,” he said.
The 10-year Treasury yield
TMUBMUSD10Y,
1.209%
has climbed 28.6 basis points in the year to date to 1.199% as of Friday.
But with last year’s sharp price increases, is the U.S. housing market at least at risk of overheating?
“Not at current interest rates,” said John Beacham, the founder and CEO at Toorak Capital, which finances apartment buildings and single family rental properties, including those going through rehabilitation and construction projects.
“Over the course of the year, more people will go back to work,” Beacham said, but he added that it’s important for policy makers in Washington to provide a bridge for households through the pandemic, until spending on socializing, sporting events, concerts and more can again resemble a time before the pandemic.
“Clearly, there likely will be short-term consumption increase,” he said. “But after that it normalizes.”
The U.S. stock and bond markets will be mostly closed on Monday for the Presidents Day holiday.
On Tuesday, the only tidbit of economic data comes from the New York Federal Reserve’s Empire State manufacturing index, followed Wednesday by a slew of updates on U.S. retail sales, industrial production, home builders data and minutes from the Fed’s most recent policy meeting. Thursday and Friday bring more jobs, housing and business activity data, including existing home sales for January.
Scientists are settling on a road map that can help critical sectors of the economy safely conduct business, from meatpacking plants to financial services, despite the pandemic’s continued spread.
After nearly a year of study, the lessons include: Mask-wearing, worker pods and good air flow are much more important than surface cleaning, temperature checks and plexiglass barriers in places like offices and restaurants. And more public-health experts now advocate wide use of cheap, rapid tests to detect cases quickly, in part because many scientists now think more than 50% of infections are transmitted by people without symptoms.
The playbook comes after months of investigations on how the coronavirus spreads and affects the body. Scientists combined that with knowledge gained from years of experience managing occupational-health hazards in high-risk workplaces, such as factories and chemical plants, where tiny airborne pollutants can build up and cause harm. They say different types of workplaces—taking into account the types of interactions workers have—need slightly different protocols.
The safety measures have taken on new urgency in recent weeks as new infections, hospitalizations and deaths rise across the U.S. and Europe, and potentially more-transmissible variants of the virus spread around the globe. This phase of the pandemic is prompting a new wave of stay-at-home orders, closures and travel restrictions, important first steps to curbing contagion. Infection-prevention specialists say known strategies for stemming spread should continue to work against the new variants, but that increased adherence is even more important.
Vaccines are rolling out, but slowly, and access will be limited mostly to high-priority groups for some time.
“We have to still deal with ‘the right now.’ We’ve zeroed in on this set of controls that we know work,” said
Joseph Allen,
director of the Healthy Buildings Program at the Harvard T.H. Chan School of Public Health.
Over the past year, the lack of consistent and cohesive messaging among scientists and lawmakers has seeded confusion over what makes up risky behavior, what activities should be avoided and why. That is beginning to change as consensus builds and scientists better understand the virus.
In the U.S., scientists at first advised people against wearing masks, in part because of shortages, while the idea of stay-at-home orders received severe pushback from some lawmakers. Early in the pandemic, testing was limited to people with symptoms, also partly due to shortages. That advice has shifted, but a year later, sufficient testing remains a critical issue.
London’s Regent Street was nearly empty last week.
Photo:
May James/SOPA Images /Zuma Press
Countries such as New Zealand and others in Asia adhered to a combination of basic mitigation strategies from the start—particularly masking, large-scale testing and lockdowns that broke transmission chains. They have tended to fare better than those that didn’t.
In one of his first moves, President
Biden
signed executive orders to require masks be worn on federal property and at airports and other transportation hubs. The administration said it is focusing on increasing the availability of vaccines, and also stressed the importance of widely available testing, which still lags in low-income and minority communities.
The current scientific playbook follows from two of the biggest research insights since the start of the pandemic. First, individuals who aren’t showing symptoms can transmit the virus. Infectious-disease experts worry most about this silent spread and say it is the reason the pandemic has been so hard to contain. While visibly sick people can pass on the virus, data cited by the Centers for Disease Control and Prevention estimate that 40% to 45% of those infected never develop symptoms at all. With the new viral variants that can transmit more readily, the potential for silent spread is even higher, infectious-disease experts said.
Secondly, researchers now know that tiny airborne particles known as aerosols play a role in the spread of Covid-19. These can linger in the air and travel beyond 6 feet.
An early hallmark of the pandemic response focused on the risk of transmission through large respiratory droplets that typically travel a few feet and then fall to the ground. Businesses rushed to buy plexiglass barriers, creating shortages.
The barriers can be good at preventing larger virus-containing droplets from landing on and infecting healthy individuals. They may offer some protection in shielding workers who have brief face-to-face interactions with many people throughout the workday, such as cashiers and receptionists, some occupational-health experts said.
Yet in settings like offices, restaurants or gyms, the role of the barriers is murkier, because activities like talking loudly and breathing deeply create aerosols that can waft on air currents and get around shields.
A Los Angeles Apparel employee added plexiglass to sewing stations in July.
Photo:
Sarah Reingewirtz/Orange County Register/Zuma Press
Outdoor diners at Eat At Joe’s restaurant in Redondo Beach, Calif., in December.
Photo:
patrick t. fallon/Agence France-Presse/Getty Images
A gym in Milan in October.
Photo:
DANIEL DAL ZENNARO/EPA-EFE/Shutterstock
Also, installing such barriers could affect airflow throughout the space, environmental-health experts said. It is possible they could limit proper ventilation, making things worse, they said.
“There seems to be an assumption that particles are going to get stopped by the barriers, which is simply not true,” said
Lisa Brosseau,
an industrial hygienist and research consultant for the University of Minnesota’s Center for Infectious Disease Research and Policy. Airborne particles ferrying the virus “really distribute all over the place.”
The emphasis on intense surface cleaning has diminished as scientists have come to understand that indirect transmission through contaminated surfaces doesn’t play as critical a role in the spread of Covid-19 as they thought in the early days of the pandemic. In September, the CDC published sanitation guidelines for offices, workplaces, homes and schools that said that, for most surfaces, normal, routine cleaning should suffice, and that frequently touched objects, such as light switches and doorknobs, should be cleaned and disinfected.
“Sanitation is important in general always,” said
Deborah Roy,
president of the American Society of Safety Professionals. “The idea is we went overboard at the beginning because of the amount of unknowns. Now, we’re in a situation where we have more information.”
Temperature checks have become less popular among some employers because scientists now know that not all Covid-19 patients get fevers. One large study published online in November in the New England Journal of Medicine showed only 13% of Covid-19 patients reported a fever during the course of their illness.
Scientists now understand that brief encounters with an infected person can lead to spread, according to an October case study—an advance from earlier, when the rule of thumb was to avoid close contact for 15 consecutive minutes or longer. The report urged people to consider not just time and proximity in defining close contact with a Covid case, but also ventilation, crowding and a person’s likelihood of generating aerosols. Following the report, the CDC changed its definition of close contact to a total of 15 minutes or more over a 24-hour period.
A flight attendant showed an air filter on LATAM airlines in Bogota in August.
Photo:
juan barreto/Agence France-Presse/Getty Images
Fresh air and effective filters indoors are important because they can remove virus particles before they have time to infect.
Masks offer a similar benefit, by lowering the amount of particles that infected individuals emit. Some scientists say there could be a benefit to doubling up on masks, as a second layer may improve both filtration and fit, so long as the masks are worn correctly.
A study published in October found that in countries where mask wearing was the norm or where governments put in place mask mandates, coronavirus mortality rates grew much more slowly than in countries without such measures. This fall, the CDC said that masks also offer some personal protection by reducing a wearer’s exposure to infected particles.
As the weather gets colder and people head indoors, the risk of catching Covid-19 is rising. WSJ explains why air ventilation and filtration are one of our biggest defenses against the coronavirus this winter. Illustration: Nick Collingwood/WSJ
The combination of airborne particles and personal interactions, even among people who don’t feel ill, can turn wedding receptions, plane rides and choir practices into superspreading, potentially deadly events.
“For Covid, those two factors—asymptomatic spread and aerosolization—is what made mask-wearing so essential,” said
Megan Ranney,
emergency physician and assistant dean at Brown University.
Lessons can be gleaned from an outbreak at a Canadian spin studio last fall. The operators of the SPINCO studio in Hamilton, Ontario, had many public-health measures in place, including limiting the number of bikes in each class and screening staff and attendees with a questionnaire about topics including symptoms and travel. Rooms were sanitized within 30 minutes of a completed class, and towels were laundered, according to a statement provided last fall by
Elizabeth Richardson,
medical officer of health for the city of Hamilton.
Masks were also required before and after workout classes, Dr. Richardson said.
In total, 54 people who attended workouts over a span of several classes became infected. Another 31 cases were tied to the outbreak after spin-class attendees who contracted the virus then passed it on. The spin studio temporarily shut down following the outbreak and later reopened. It is currently not offering classes due to local regulations that mandated the closure of all gyms and fitness centers amid rising Covid-19 cases in the area.
In a November statement following the outbreak,
Michelle August,
founder of SPINCO, said that the company has “always put safety first and [has] exceeded all recommended guidelines from public health throughout” the pandemic. She said SPINCO has also strengthened and heightened its Covid-19 mitigation measures. SPINCO’s website currently says face masks are mandated throughout workouts in the company’s Hamilton location.
It also says that SPINCO is installing air purifiers in all of its studios that filter air in the rooms every 17 to 21 minutes. Airborne transmission experts recommend that building managers pump in clean, fresh air between three to six times an hour and that they install filters that are proven to effectively trap and remove a substantial number of virus-carrying particles.
To film a stage play of “A Christmas Carol” in November, the Guthrie Theater in Minneapolis upgraded its air filters and increased the rate at which the ventilation system pumps in outside air, said
Brooke Hajinian,
the Guthrie’s general manager. Management staggered arrival times, and a compliance officer made sure everyone socially distanced, wore their masks properly and washed their hands.
The theater divided staff into pods depending on how close they must get to the lone actor on stage, who portrayed Charles Dickens and didn’t wear a mask while performing, according to Ms. Hajinian. Those working nearest the stage underwent testing three times a week and wore N95 masks at all times, she said, while cleaning and security crews, who didn’t interact with the stage crews, wore cloth masks and didn’t undergo testing.
Actor Nathaniel Fuller performed in ‘A Christmas Carol’ at the Guthrie Theater in Minneapolis.
Photo:
Kaitlin Schlick
Ms. Hajinian said she monitored the staff’s testing results and symptoms. “Any symptom is not a failure of this plan,” she said. Catching a case “and isolating it—that’s what success looks like for us,” she said. There were no cases, she said.
Scientists say multilayered safety efforts are needed because no single prevention method is 100% effective.
One of the largest studies of asymptomatic transmission to date showed that frequent testing was essential in identifying infections among a group of nearly 2,000 Marine recruits required to socially distance and wear masks except while eating and sleeping.
The study looked at cases identified with lab-based tests that search out and amplify the genetic material of the virus, but those tests aren’t as easily scaled as so-called rapid antigen tests, which search for viral proteins.
Results from lab-based tests can sometimes take days, while results from rapid tests are usually available in less than an hour. As a result, some epidemiologists have been advocating for widespread use of antigen tests to prevent outbreaks, because they are cheaper and don’t require high-tech laboratory equipment to run, meaning they can be deployed in a broader range of settings.
The shift toward using frequent, inexpensive and rapid tests on the same people multiple times a week to screen entire populations—instead of one-time tests on individuals who have symptoms—will be important to efficiently break transmission chains, epidemiologists said.
“Unless we’re doing really broad, frequent screening of the people at large, we’re completely missing the vast majority” of infections, said
Michael Mina,
an assistant professor of epidemiology at the Harvard T.H. Chan School of Public Health. “We have to change how we’re doing this.”
A Covid-19 testing site at the Alemany Farmers Market in San Francisco in November.
Photo:
David Paul Morris/Bloomberg News
While rapid tests tend to be less sensitive than lab-based tests, Dr. Mina said the data suggest they have high sensitivity when people are most likely to be infectious.
Other infectious-disease experts have touted contact tracing to identify and bust clusters of infection. But they say the strategy works best when cases aren’t surging, as they are now. When transmission rates are too high, limiting gatherings, travel and crowding are more effective at denting spread, said
Abraar Karan,
a global-health physician at Brigham and Women’s Hospital and Harvard Medical School.
In places without big surges, a high-tech approach is becoming increasingly useful: genetic epidemiology, or tracking tiny changes in viral genomes to map out transmission chains. As the coronavirus replicates and moves from person to person, its genes change slightly. Sometimes, those tiny changes are unusual, and they can be particularly useful in mapping transmission events, according to
Justin O’Grady,
an infectious disease expert at the Quadram Institute in the U.K.
By sifting through the differences among more than 1,000 viral genomes, Dr. O’Grady and his collaborators found that a particular viral variant was moving through multiple nursing homes in the U.K., among patients and staff, but not among the wider community. The unpublished data suggested that transmission was facilitated by the movement of staff from one facility to another, Dr. O’Grady said. The team relayed the findings to government authorities and advised them to restrict staff moving among facilities during the pandemic.
“Sometimes genomic epidemiology is able to find hidden transmission links that traditional epidemiology would struggle to find,” Dr. O’Grady said. “We can’t stop transmission, but when we find a superspreader event…we can bring in the right prevention methods to stop it from spreading further.”
A London ad urged safety measures last week.
Photo:
Dinendra Haria/London News Pictures /Zuma Press
—Betsy McKay contributed to this article.
Write to Daniela Hernandez at daniela.hernandez@wsj.com, Sarah Toy at sarah.toy@wsj.com and Caitlin McCabe at caitlin.mccabe@wsj.com
For as long as she can remember, the Guardian’s Jenny Stevens has had a difficult relationship with food and a feeling of being ill at ease with her body. As she moved through her teens into her 20s, these feelings intensified until she found herself skipping more and more meals while in the grip of anorexia.
She tells Rachel Humphreys that having recognised the problem herself, it was far from easy to get the treatment she needed. Faced with an obstructive GP, she was unable to get the referral she required for specialist care. Eventually she was referred to the eating disorder unit at the Maudsley hospital, south London, where she was able to begin the gradual road to recovery.
