- Among fully vaccinated, study shows Paxlovid does not shorten symptoms University of Minnesota Twin Cities
- Paxlovid Fails to Shorten COVID in Standard-Risk and Vaccinated At-Risk Patients Medpage Today
- Predictors of nirmatrelvir–ritonavir receipt among COVID-19 patients in a large US health system | Scientific Reports Nature.com
- Paxlovid is effective against Covid-19, but many people eligible for it are not getting it; it’s fre … The Lexington Times
- Nirmatrelvir-Ritonavir Does Not Speed Alleviation of COVID-19 Symptoms HealthDay
Tag Archives: Paxlovid
Paxlovid didn’t shorten Covid symptoms in vaccinated adults, full trial results confirm – Endpoints News
- Paxlovid didn’t shorten Covid symptoms in vaccinated adults, full trial results confirm Endpoints News
- Among fully vaccinated, study shows Paxlovid does not shorten symptoms University of Minnesota Twin Cities
- Paxlovid Fails to Shorten COVID in Standard-Risk and Vaccinated At-Risk Patients Medpage Today
- Predictors of nirmatrelvir–ritonavir receipt among COVID-19 patients in a large US health system | Scientific Reports Nature.com
- Paxlovid is effective against Covid-19, but many people eligible for it are not getting it; it’s fre … The Lexington Times
‘If it’s COVID, Paxlovid’? For many, it should be easier to get. Here’s what to know about antivirals – Yahoo News
- ‘If it’s COVID, Paxlovid’? For many, it should be easier to get. Here’s what to know about antivirals Yahoo News
- Underuse of Antiviral Drugs to Prevent Progression to Severe COVID-19 — Veterans Health Administration, March–September 2022 | MMWR CDC
- Here’s why some high-risk patients aren’t getting drugs to combat COVID The Seattle Times
- Why More People Should be Prescribed Paxlovid for COVID | Johns Hopkins | Bloomberg School of Public Health Johns Hopkins Bloomberg School of Public Health
- COVID drugs more often given to Medicare patients who least need them, study suggests University of Minnesota Twin Cities
Some people are experiencing ‘Paxlovid rebound’ after taking the COVID antiviral pill. Here’s what you should know.
When the antiviral medication Paxlovid was approved in 2021 to treat COVID-19, doctors began noticing a perplexing trend among some of the patients who took the medication: a rebound case of the virus. After treatment, some people would recover and test negative for the virus, only to test positive or have symptoms come back a few days later. “Paxlovid rebound,” as it’s known, received a lot of media attention when President Biden, first lady Jill Biden, as well as Drs. Anthony Fauci and Rochelle Walensky, director of the Centers for Disease Control and Prevention, all experienced it last year after taking the medication.
Scientists are not sure why this rebound effect occurs when taking Paxlovid, but here are a few things we do know.
What is Paxlovid? How does it work?
Paxlovid is an oral antiviral pill that can be prescribed to people who come down with COVID-19 and are at risk for developing severe disease. This can be individuals who are unvaccinated, the elderly or people with other medical conditions, such as cancer or diabetes. The drug, developed by Pfizer, can protect these high-risk patients from needing hospitalization. Those who are vaccinated but who are at risk for severe outcomes of COVID-19 can also benefit from taking Paxlovid.
U.S. regulators granted emergency use authorization for Paxlovid in December 2021. Today the drug is available by prescription only, from a physician or pharmacist. Anyone ages 12 and older who weighs at least 88 pounds and who is at high risk for severe disease is eligible for the medication. Patients with severe kidney disease — or who are on dialysis — or people with severe liver disease, however, should not take Paxlovid. The drug can also interact with other medications such as those that treat high cholesterol, high blood pressure and migraines, so patients taking these drugs should avoid taking Paxlovid.
Like many antivirals, Paxlovid works best when taken early in the course of illness. The CDC recommends treatment begin within the first five days of experiencing symptoms. Once a person is prescribed the medication, they will take three Paxlovid pills twice a day for five days for a full course that adds up to 30 pills.
The antiviral therapy consists of a combination of two oral antiviral drugs — nirmatrelvir and ritonavir — which work together to stop the viral replication process. By reducing a person’s viral load, the medication lessens the severity of their symptoms.
In clinical trials, which were conducted when the Delta variant was predominant, Paxlovid was found to reduce the risk of hospitalization or death by 89% in high-risk people. Since its approval, many clinical studies that have been conducted around the world have also confirmed the drug’s high level of protection against hospitalization and death.
With Omicron being a highly immune-evasive variant that has rendered many antibody treatments ineffective, vaccine experts worried that Paxlovid would lose its effectiveness too. Fortunately, that doesn’t seem to be the case. According to recent research, the drug continues to offer significant protection against hospitalization and death and can also offer a substantial benefit even to vaccinated patients diagnosed with COVID-19.
Other studies, however, have found no evidence of Paxlovid benefiting people younger than age 65.
“I don’t think we need to push Paxlovid in every 20-year-old who comes down with COVID or 35-year-old who’s healthy,” Dr. Bruce Farber, chief of public health and epidemiology at Northwell Health, the largest health care system in New York state, told Yahoo News. “But in those who are at high risk, those who are elderly, who have not been vaccinated, those who have comorbidities, those who are immunosuppressed, [for] those people [it] can make a significant difference,” he added.
In addition to keeping high-risk patients from getting very sick, Paxlovid can reduce the risk of symptoms of long COVID, a November study conducted by the Department of Veterans Affairs found.
What is Paxlovid rebound?
The CDC defines Paxlovid rebound as when, after completing the full five-day course of treatment, a person experiences either a reemergence of symptoms or tests positive after having tested negative for COVID-19. According to the CDC, this rebound effect tends to occur between two and eight days after initial recovery. But experiencing a rebound, the agency said, doesn’t mean that a person was resistant to Paxlovid, nor does it mean they were reinfected with the virus. Additionally, the CDC has said Paxlovid rebound cases are typically mild, resolve within a few days, and there’s no evidence that additional treatments are needed for these patients.
Despite Paxlovid’s efficacy even in the setting of Omicron, the medication is being underutilized in the U.S. and other parts of the world. According to a report by the London-based health analytics firm Airfinity, U.S. physicians have prescribed the drug in only about 13% of new COVID-19 cases, Nature recently reported. Experts have said concerns about suffering from potential Paxlovid rebound is one of the reasons this may be happening.
Farber also said that another reason Paxlovid is being underutilized has to do with the virus itself.
“This virus is much less virulent even though it’s more contagious,” he said, adding that the need for Paxlovid “became less.”
Scientists are still studying why this rebound effect occurs when taking Paxlovid, as well as who is more likely to experience it. However, recent research has found that rebound can also happen to people who develop COVID-19 and don’t take Paxlovid. Studies are underway to understand why this happens, Farber said.
“More recent data suggests that rebound also occurs in people who recover from COVID who have not gotten Paxlovid, and it occurs at probably similar rates, whether you take Paxlovid or not,” Farber said, adding that rebound cases after taking the drug were initially thought to occur in roughly 5% of cases but that research has shown it may happen more often than initially thought. “More recent articles say it may be as common as 10 or 15% of cases,” he said.
What to do if you experience Paxlovid rebound
If someone’s symptoms return or they test positive after Paxlovid treatment, the CDC advises following its isolation guidance and quarantining again for five days. Isolation can end after this period if a person is fever-free for 24 hours without the use of fever-reducing medications. The agency also recommends wearing a mask for 10 days after rebound symptoms start.
The CDC encourages doctors and patients to report Paxlovid rebound cases to Pfizer’s portal for adverse events associated with the drug.
Finally, Farber said that Paxlovid rebound is still fairly uncommon and that it shouldn’t deter people and their doctors from using the life-saving medication when needed.
“In theory, it could prolong their isolation. But I think [people] should realize that this can occur even without Paxlovid. So it becomes really not an important distinguisher, of whether they get it or not,” he said.
Pfizer CEO says there will be no generic Paxlovid for China
An online pharmacy lists Pfizer’s oral anti-Covid drug Paxlovid for 2,980 yuan per box in in Suqian, Jiangsu province, China on Dec. 13, 2022.
CFOTO | Future Publishing | Getty Images
Pfizer is not in talks with Chinese authorities to license a generic version of its Covid-19 treatment Paxlovid for use there, but is in discussions about a price for the branded product, Chief Executive Albert Bourla said on Monday.
Reuters reported on Friday that China was in talks with Pfizer to secure a license that will allow domestic drugmakers to manufacture and distribute a generic version of the U.S. firm’s Covid-19 antiviral drug Paxlovid in China.
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Referring to that report, Bourla speaking at JPMorgan’s healthcare conference in San Francisco, said “We are not in discussions. We have an agreement already for local manufacturing of Paxlovid in China. So we have a local partner that will make Paxlovid for us, and then we will sell it to the Chinese market.”
Bourla said the company had shipped thousands of courses of the treatment in 2022 to China and in the past couple of weeks, had increased that to millions.
On Sunday, China’s Healthcare Security Administration (NHSA) said that the country would not include Paxlovid in an update to its list of medicines covered by basic medical insurance schemes as the U.S. firm quoted a high price for the Covid-19 drug.
Bourla said that talks with China on future pricing for the treatment had broken off after China had asked for a lower price than Pfizer is charging for most lower middle income countries.
“They are the second highest economy in the world and I don’t think that they should pay less than El Salvador,” Bourla said.
Still, Bourla said the removal from the list would not have an effect on the company’s business there until April. He said the company had shipped millions of courses of the drug to China in recent weeks.
The company could end up selling only to the private market in China, he said.
Study finds Paxlovid can interact badly with some heart medications, and White House renews COVID emergency through Jan. 11
A new study has found that the COVID antiviral Paxlovid can interact badly with certain heart medications, raising concerns for patients with cardiovascular risk who test positive.
The study was published in the Journal of the American College of Cardiology and found the reaction involved such medications as blood thinners and statins. As patients who are hospitalized with COVID are at elevated risk of heart problems, they are likely to be described Paxlovid, which was developed by Pfizer
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“Co-administration of NMVr (Paxlovid) with medications commonly used to manage cardiovascular conditions can potentially cause significant drug-drug interactions and may lead to severe adverse effects,” the authors wrote. “It is crucial to be aware of such interactions and take appropriate measures to avoid them.”
The news comes just days after the White House made a renewed push to encourage Americans above the age of 50 to take Paxlovid or use monoclonal antibodies if they test positive and are at risk of developing severe disease.
White House coordinator Dr. Ashish Jha told the New York Times that greater use of the medicine could reduce the average daily death count to about 50 a day from close to 400 currently.
“I think almost everybody benefits from Paxlovid,” Jha said. “For some people, the benefit is tiny. For others, the benefit is massive.”
Yet a smaller share of 80-year-olds with COVID in the U.S. is taking it than 45-year-olds, Jha said, citing data said he has seen.
On Thursday, the White House extended its COVID pubic health emergency through Jan. 11 as it prepares for an expected rise in cases in the colder months, the Associated Press reported.
The public health emergency, first declared in January 2020 and renewed every 90 days since, has dramatically changed how health services are delivered.
The declaration enabled the emergency authorization of COVID vaccines, as well as free testing and treatments. It expanded Medicaid coverage to millions of people, many of whom will risk losing that coverage once the emergency ends. It temporarily opened up telehealth access for Medicare recipients, enabling doctors to collect the same rates for those visits and encouraging health networks to adopt telehealth technology.
Since the beginning of this year, Republicans have pressed the administration to end the public health emergency.
President Joe Biden, meanwhile, has urged Congress to provide billions more in aid to pay for vaccines and testing. Amid Republican opposition to that request, the federal government ceased sending free COVID tests in the mail last month, saying it had run out of funds for that effort.
Separately, the head of the World Health Organization urged countries to continue to surveil, monitor and track COVID and to ensure poorer countries get access to vaccines, diagnostics and treatments, reiterating that the pandemic is not yet over.
Tedros Adhanom Ghebreyesus said most countries no longer have measures in place to limit the spread of the virus, even though cases are rising again in places including Europe.
“Most countries have reduced surveillance drastically, while testing and sequencing rates are also much lower,” Tedros said in opening remarks at the IHR Emergency Committee on COVID-19 Pandemic on Thursday.
“This,” said the WHO leader, “is blinding us to the evolution of the virus and the impact of current and future variants.”
U.S. known cases of COVID are continuing to ease and now stand at their lowest level since late April, although the true tally is likely higher given how many people overall are testing at home, where the data are not being collected.
The daily average for new cases stood at 38,530 on Thursday, according to a New York Times tracker, down 19% from two weeks ago. Cases are rising in six states, namely Nevada, New Mexico, Kansas, Maine, Wisconsin and Vermont, and are flat in Wyoming. They are falling everywhere else.
The daily average for hospitalizations was down 7% at 26,665, while the daily average for deaths is down 7% to 377.
Coronavirus Update: MarketWatch’s daily roundup has been curating and reporting all the latest developments every weekday since the coronavirus pandemic began
Other COVID-19 news you should know about:
• Federal Health Minister Karl Lauterbach has urged German states to reintroduce face-mask requirements for indoor spaces due to high COVID cases numbers, the Local.de reported. Lauterbach was launching his ministry’s new COVID campaign on Friday. “The direction we are heading in is not a good one,” he said at a press conference in Berlin, adding it’s better to take smaller measures now than be forced into drastic ones later.
• Health officials in Washington and Oregon said Thursday that a fall and winter COVID surge is likely headed to the Pacific Northwest after months of relatively low case levels, the AP reported. King County (Wash.) Health Officer Dr. Jeff Duchin said during a news briefing that virus trends in Europe show a concerning picture of what the U.S. could soon see, the Seattle Times reported.
• Kevin Spacey’s trial on sexual-misconduct allegations will continue without a lawyer who tested positive for COVID on Thursday, Yahoo News reported. The “American Beauty” and “House of Cards” star is on trial in Manhattan federal court facing allegations in a $40 million civil lawsuit that he preyed upon actor Anthony Rapp in 1986 when Rapp was 14 and Spacey was 26. Jennifer Keller’s diagnosis comes after she spent about five hours cross-examining Rapp on the witness stand over two days — a few feet away from the jury box without wearing a mask.
• A man who presents himself as an Orthodox Christian monk and an attorney with whom he lived fraudulently obtained $3.5 million in federal pandemic relief funds for nonprofit religious organizations and related businesses they controlled, and spent some of it to fund a “lavish lifestyle,” federal prosecutors said Thursday. Brian Andrew Bushell, 47, and Tracey M.A. Stockton, 64, are charged with conspiracy to commit wire fraud and unlawful monetary transactions, the U.S. attorney’s office in Boston said in a statement, as reported by the AP.
Here’s what the numbers say:
The global tally of confirmed cases of COVID-19 topped 623.9 million on Monday, while the death toll rose above 6.56 million, according to data aggregated by Johns Hopkins University.
The U.S. leads the world with 96.9 million cases and 1,064,821 fatalities.
The Centers for Disease Control and Prevention’s tracker shows that 226.2 million people living in the U.S., equal to 68.1% of the total population, are fully vaccinated, meaning they have had their primary shots. Just 110.8 million have had a booster, equal to 49% of the vaccinated population, and 25.6 million of those who are eligible for a second booster have had one, equal to 39% of those who received a first booster.
Some 14.8 million people have had a shot of the new bivalent booster that targets the new omicron subvariants.
Paxlovid: Covid-19 treatment can interact with common heart medications, doctors warn
CNN
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Covid-19 patients with a history of cardiovascular disease are at an increased risk of developing severe illness and could benefit most from the Covid-19 treatment Paxlovid – but there’s a catch.
Paxlovid can have dangerous interactions with some of the most common medications for cardiovascular disease, including certain statins and heart failure therapies, a new paper warns.
The review paper, published Wednesday in the Journal of the American College of Cardiology, lists dozens of cardiovascular medications and whether they are safe to give along with Paxlovid or whether they could have interactions.
Some medications such as aspirin are safe to take with Paxlovid, according to the paper, but other drugs could have interactions, and therefore, their dosage should be adjusted or temporarily discontinued while a patient is taking Paxlovid.
When President Joe Biden tested positive for Covid-19 and started Paxlovid in July, his physician Dr. Kevin O’Connor temporarily took him off Crestor and Eliquis, two heart medications that the President takes for his pre-existing conditions. Doctors say there is no short-term risk to stopping these drugs.
The review paper says that interactions between Paxlovid and certain blood thinners can cause an increased risk of bleeding. Interactions between Paxlovid and some cholesterol medications such as statins can be toxic to the liver, and interactions between Paxlovid and certain blood pressure medications could cause low blood pressure, flushing and swelling.
“There are some drugs that you simply will not be able to stop, and a doctor will have to make a decision. It’s a risk-benefit analysis,” said Dr. Jayne Morgan, a cardiologist and clinical director of the Covid Task Force at Piedmont Hospital/Healthcare in Atlanta, who was not involved in the new paper.
For cardiovascular medications that patients could discontinue in order to take Paxlovid, Morgan noted that the Covid-19 treatment is a five-day regimen.
“You’ve got to make the diagnosis and then stop your drugs and have all of that done in time to still meet that five-day window,” Morgan said, adding that people will have to consult with their doctors about what’s best for them.
The authors of the new paper – from Lahey Hospital and Medical Center, Harvard Medical School and other US institutions – wrote that Paxlovid should be avoided when potentially interacting cardiovascular medications cannot be “safely interrupted.”
Paxlovid, an oral antiviral drug, was authorized in December for the treatment of mild to moderate Covid-19 in people 12 and older who are at high risk of severe illness, hospitalization or death.
“Awareness of the presence of drug-drug interactions of Paxlovid with common cardiovascular drugs is key. System-level interventions by integrating drug-drug interactions into electronic medical records could help avoid related adverse events,” the paper’s senior author, Dr. Sarju Ganatra, director of the cardio-oncology program at Lahey Hospital and Medical Center in Massachusetts, said in a news release.
“The prescription of Paxlovid could be incorporated into an order set, which allows physicians, whether it be primary care physicians or cardiology providers, to consciously rule out any contraindications to the co-administration of Paxlovid. Consultation with other members of the health care team, particularly pharmacists, can prove to be extremely valuable,” Ganatra said. “However, a health care provider’s fundamental understanding of the drug-drug interactions with cardiovascular medications is key.”
Interactions between Paxlovid and common heart medications are well known, said Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, who was not involved in the new paper.
“Drug interactions have been reported, but I think that Paxlovid has been prescribed so widely that some doctors and patients may not be as attuned as they should be,” Barouch said.
Paxlovid is made of two antivirals, nirmatrelvir and ritonavir.
“The second drug, ritonavir, is a nonspecific drug that inhibits metabolism and increases the dose of the other drug. But the ritonavir in Paxlovid also can inhibit the metabolism of other drugs. So you have to be really careful when you prescribe Paxlovid for people who are on certain blood thinners, cardiac medications, statins and other drugs,” Barouch said. “So it’s not just a free pass.”
Can you combine Paxlovid with other COVID-19 drugs? FDA says no, for some
Taking Pfizer’s blockbuster COVID-19 pills, Paxlovid, at the same time as a rival’s treatment for the virus might be safe and more effective than either drug alone, federal scientists have found.
The combination might also offer a solution to so-called “rebound” cases, when patients see a return of symptoms after finishing off a course of Paxlovid.
But more research is needed, and the Food and Drug Administration does not currently allow doctors to prescribe both drugs to a patient.
The findings, published this month as a preprint that has yet to be peer-reviewed, come from a study run by the National Institutes of Health in monkeys.
After being infected by the Delta variant, some were given both Paxlovid and Lagevrio — the COVID-19 antiviral drug produced by Merck and Ridgeback Biotherapeutics.
Animals who got both treatments saw “decreased SARS-CoV-2 shedding and replication” early on in their infection, and “milder disease” compared to those who got only one drug or the other. The researchers saw no concerning reactions among animals who got the two drugs.
However, the study’s authors cautioned that there were key questions that will need to be addressed in future human trials and experiments with the two drugs. And for now, the FDA says doctors are not allowed to prescribe Paxlovid to patients at the same time as Lagevrio.
Greenlighted last year under the name molnupiravir, Lagevrio is only authorized by the FDA for use in patients where alternative options “are not accessible or clinically appropriate.”
Lagevrio carries additional warnings that Paxlovid does not, like risks it could pose to reproduction — it should not be taken during pregnancy — and the chance it could lead to new, worrying variants.
“Therefore, if a patient is taking Paxlovid, an alternative COVID-19 treatment option authorized by the FDA, they would not be eligible for Lagevrio,” Chanapa Tantibanchachai, a spokesperson for the agency, said in a statement.
Another treatment option, Eli Lilly’s bebtelovimab, carries the same kind of requirement, which effectively bars providers from combining the monoclonal antibody drug with Pfizer’s pills.
“No data” on how to treat rebound
Earlier this year, South Korean researchers reported in a preprint that they had found a “profound” improvement in mice who were given both drugs.
The NIH’s study tested the two drugs in rhesus macaques, the “closest surrogate to humans.”
But while the study’s authors speculated the combination might “counteract the ‘rebound effect’,” the animals in their experiment only received four days of treatment before autopsies were conducted.
By contrast, rebound cases in COVID patients have generally been reported a few days after the person finishes the full five-day course of Paxlovid.
In an email, the National Institutes of Health’s Dr. Heinz Feldmann blamed the early end to the study on “viral kinetics”: Before the animals’ virus levels dropped too low, the scientists wanted to be able to compare samples from of the viral load in different parts of the body.
“We went for peak virus replication (day 3 or 4) to better show the efficacy of the treatment,” Feldmann wrote.
The approach has sparked interest in part because the two drugs work in different ways. Paxlovid works by blocking the process by which the virus replicates in the body. Lagevrio aims to battle the virus by creating too many errors as it replicates.
“Combination antivirals are the rule in other viral diseases, for example HIV and hepatitis C. The combination of antivirals can enhance the potency and decrease the risk of the emergence of resistant viruses,” Dr. Roy Gulick, chief of the division of infectious diseases at Weill Cornell Medicine, said in an email.
Gulick is co-chair of the NIH’s COVID-19 Treatment Guidelines panel, which has continued to publish updated recommendations for doctors treating patients throughout the pandemic.
He also pointed to other viruses that do not need more than one antiviral, like herpes and hepatitis B.
“It’s potentially worth studying in humans, but it may be challenging to improve upon the 89% success rate of Paxlovid,” Gulick wrote, citing Pfizer’s initial results in high-risk unvaccinated adults.
In August, the FDA said it would amend Pfizer’s emergency use authorization to require a clinical trial to study rebound cases. The company says it plans to study “retreatment” with another course of Paxlovid for these patients.
So far, the NIH panel’s recommendations for doctors treating rebound cases say that there is “currently no data on the efficacy of administering longer courses or a second course of ritonavir-boosted nirmatrelvir.”
Dr. Anthony Fauci, the president’s outgoing chief medical adviser, is among the Americans who have reported battling a COVID rebound.
The 81-year-old told the “NIH Record” that he sought out a second course of the pills, after he came down with the return of symptoms.
“I got much more sick than I was the first time around,” said Fauci.
Biden tests positive for coronavirus again after Paxlovid ‘rebound’
O’Connor said in a letter that Biden has experienced no reemergence of symptoms and “continues to feel quite well.”
“This being the case, there is no reason to reinitiate treatment at this time, but we will obviously continue close observation,” O’Connor wrote. Biden will go back into isolation at the White House, O’Connor added.
Biden was scheduled to travel to Wilmington, Del., on Sunday and Hemlock, Mich., on Tuesday, but both trips have been canceled, two White House officials said.
The trip to Michigan was for an event in support of a $52 billion bill to subsidize computer chip manufacturing and research and counter China’s influence, known as the CHIPS and Science Act. The legislation passed both chambers of Congress this week and is awaiting Biden’s signature. It was unclear whether Biden would participate in Tuesday’s event remotely.
Biden was likely infected with the BA.5 variant, O’Connor said last week, an omicron subvariant that has become dominant in the United States and is the most transmissible version of the virus yet. BA.5 has shown a remarkable ability to escape immune protection afforded by vaccines and prior coronavirus infection.
Biden emerged from his five-day isolation on Wednesday and delivered a speech from the Rose Garden about how his mild covid infection was a reflection of the administration’s pandemic response and the tools it had made widely available, including antivirals, at-home tests and boosters.
He conducted a series of public events this week in support of the CHIPS bill and on the economy. Biden did not hold any public events on Friday.
Biden removed his mask for some of the events. White House press secretary Karine Jean-Pierre said Biden was still in compliance with guidelines from the Centers for Disease Control and Prevention because he was more than six feet apart from others.
CDC guidance recommends people isolate for five days after testing positive for coronavirus and wear a mask for an additional five days when around others. Some experts have said the guidance could cause people to return to work or leave isolation when they are potentially still infectious.
Besides Biden, notable figures who experienced rebound infections include 81-year-old Anthony S. Fauci, the president’s chief medical adviser, who contracted the coronavirus earlier this summer. The rebound infection can also lead to further complications, as with the initial infection, but many people describe their symptoms as mild.
Paxlovid, which is taken in a five-day course, suppresses the amount of virus in a person’s system while the treatment is being taken. Some experts theorize that the rebound infections occur because the five-day course is too short and should be lengthened by several days, to ensure that the virus has been eradicated.
Biden addressed his rebound case on Twitter on Saturday but reassured people he was continuing to work and would resume traveling soon.
“Folks, today I tested positive for COVID again. This happens with a small minority of folks,” Biden wrote on Twitter. “I’ve got no symptoms but I am going to isolate for the safety of everyone around me. I’m still at work, and will be back on the road soon.”
Dan Diamond contributed to this report.
Covid rebound: Coronavirus can be contagious during a Paxlovid rebound, researchers warn, even if people don’t have symptoms
“People who experience rebound are at risk of transmitting to other people, even though they’re outside what people accept as the usual window for being able to transmit,” said Dr. Michael Charness of the Veterans Administration Medical Center in Boston.
Charness and his colleagues recently collaborated with a team of researchers at Columbia University to look into cases of Covid-19 that return after Paxlovid treatment. He said they’ve found at least two instances in which people have transmitted to others when their infection recurs.
In one case, a 67-year-old man infected a 6-month-old after a half-hour near the child.
The man was 12 days past his first positive Covid-19 test. He had taken a five-day course of Paxlovid and was feeling better. He didn’t have any symptoms when he saw the baby, who was his grandson, but about eight hours later, he started to feel ill again.
The baby tested positive about three days later, as did both of his parents. Neither the baby nor its parents had any other close contacts before they got sick.
“It indicates that you can transmit during rebound even before you develop symptoms,” Charness said. “And you know, we studied a small number of people. It’s certainly conceivable that there are other people out there who don’t have symptoms and still have a viral rebound.”
In another instance, a 63-year-old man infected two family members during three days of relapse after Paxlovid.
Take precautions after Paxlovid
Based on this research, the US Centers for Disease Control and Prevention issued new guidance last week for people experiencing Covid-19 rebound after Paxlovid.
The CDC said people who test positive again and whose symptoms come back after finishing their antiviral pills should restart their isolation period and isolate for five full days. The agency says people can end their isolation period after those five additional days as long as their fever has been gone for 24 hours without fever-reducing medication and they’re feeling better. The agency also recommends that people wear a mask for 10 days after their symptoms come back.
The findings and guidance come as Paxlovid use has increased in the United States. According the White House, over the past two months, filled prescriptions for Paxlovid have climbed from about 27,000 a week to 182,000 a week.
The administration credits the increase to its test-to-treat program, which created one-stop hubs in grocery and drug stores where people could take a Covid-19 test and immediately receive and fill a prescription for antiviral medications. The antiviral drugs should be taken within the first few days of symptoms.
The drug works well. In clinical trials, Paxlovid reduced the odds that a person at risk of severe Covid-19 would need to be hospitalized by almost 90% compared with a placebo.
For that reason, the CDC says, early treatment with this medication is still recommended.
As helpful as it is, though, researchers say people should be aware the drug may not completely extinguish the infection.
Charness and his co-authors have now collected at least 10 such cases of Covid-19 recurrence after Paxlovid. Half of them have come from just two families, leading the researchers to conclude that such cases are not all that rare.
The research is shared as a preprint. It has not been scrutinized by outside researchers or published in a medical journal.
Genetic testing suggests that when people get a second round of Covid-19 after Paxlovid, it’s not because they’ve been infected by a different strain of the virus. There’s also no sign that the virus has changed or mutated to develop some kind of resistance to the drug.
So far, rebound cases have been mild. There haven’t been any reports of severe disease during a Covid-19 relapse. Because of this, the CDC says, there’s no reason to think that more treatment is needed.
Cause still not known
Why this might be happening is still a mystery.
In his studies, Charness said, the researchers watched the amount of virus in a person’s body — called their viral load — go down on Paxlovid treatment.
“People take Paxlovid, and what we know it does very well is, it blocks viral replication,” he said. And so the levels of virus go down. But then in some people — no one knows how many, because not enough people have been studied — levels of the virus begin to climb again nine to 12 days after they first test positive, Charness said.
It’s not entirely clear that taht rebound is linked to Paxlovid. In studies of more than 2,200 Covid-19 patients, Pfizer, the company that makes the drug, said there were a few patients who had their Covid-19 come bouncing back after a negative test, but they were in the group that took Paxlovid as well as in those who got the placebo, suggesting that Covid just reappears in some people, even without treatment.
Charness’ team has done its own comparison study, however, and found something different. When researchers looked at 1,000 cases of Covid-19 diagnosed between December and March in players and support staff of the National Basketball Association who had not taken the drug, they didn’t find any cases of Covid-19 returning. This study is still unpublished.
They say more research is needed to understand whether there could be any connection to the drug.
Charness said the fact that the infection can come back this way after treatment presents some questions. For one, would rebound be as common in people who started the drug later, maybe on day four or five after their first symptoms, after their immune systems have had longer to initially see the virus? Would a longer course of treatment — maybe taking the drug for six or seven days, rather than five — lower the risk that the virus would come back?
“No one knows,” he said. “Somebody should be studying this.”