It is OK to get a flu shot and a Covid-19 vaccine on the same day, the Centers for Disease Control and Prevention says. Officials suggest getting them in different arms, or at least an inch apart if in the same arm.
“Other than maybe making your arm more sore or having two arms that are sore, there’s not a whole lot of interaction between the two of them,” says Rachel Presti, an infectious-disease physician at Washington University in St. Louis. She’s had patients get both vaccines on the same day. “We know from other vaccines that generally giving them together is fine.”
The timing of Covid boosters and flu shots is one of many questions that people are asking their doctors as flu season arrives.
Covid-19 precautions suppressed flu cases last year, but public-health officials expect the flu to return this season. Lower lingering protection from fewer flu cases last year and higher levels of other viruses this year both signal the potential for a tough flu season.
Here’s what to know about flu shots, Covid-19 vaccines and the winter virus season.
Children’s vaccinations for Covid-19 and flu
With the
Pfizer
vaccine expected to be authorized for children 5 to 11 years old in coming weeks, doctors say it could pose a good opportunity to get them vaccinated for the flu too, if they aren’t already.
“We have so many combination vaccines, and they are really well tolerated,” says Suzanne Kaseta, chief medical officer of Boston Children’s Health Physicians, a multi-specialty pediatric practice with about 60 offices in New York and Connecticut. “Little infants are given many vaccines on the same day. It’s completely safe. The immune system can handle it.”
More flu cases this year
Predicting the flu season can be as tricky as the weather forecast, but there are several reasons some doctors think cases of flu will be higher than normal this year.
Flu immunity comes in two ways: through natural infection and through vaccines. Because there was so little flu last year, fewer people than usual have protection from infections last season. “There was essentially no infection last year to boost natural immunity, so we are relying on whatever natural immunity was pre-Covid,” says Richard Zimmerman, an infectious-disease epidemiologist and professor at the University of Pittsburgh, who works on flu modeling.
Dr. Zimmerman says models that he and the university’s public-health dynamics lab published in two non-peer reviewed preprints predict a surge in flu cases this season with at least 100,000 more hospitalizations than normal.
Patterns of other viruses provide clues about the flu season, too. Andrew Pekosz, a virologist at Johns Hopkins Bloomberg School of Public Health, says the usual progression of respiratory viruses in a population is the rhinovirus, or common cold, followed by respiratory syncytial virus, or RSV, and then influenza.
“We’re seeing a lot of rhinovirus, a lot of RSV in kids, and my prediction is we’re going to see influenza come back this year,” says Dr. Pekosz.
How effective are the flu shots?
Making the flu vaccine is an annual challenge because it is hard to know which strains will circulate in the coming season, and the virus is notorious for mutating quickly.
Still, doctors say getting a shot is always useful because it provides protection for various strains that often circulate together, and there is evidence that it can lessen the severity of the illness if you still get sick.
This year’s vaccine provides protection against four strains: two influenza A strains and two B strains.
It is too early to know if this year’s flu vaccine is a good match for the strains that will eventually circulate. But Lynnette Brammer, head of the CDC’s domestic influenza surveillance team, says the strains currently circulating are in the vaccine. “They appear to be a good representation of the viruses that are out there,” she says.
Different flu vaccines
The CDC doesn’t recommend one flu vaccine over another and says to get whatever vaccine is available. Some vaccines are recommended for particular age groups, and some types should be avoided by people with certain allergies or by pregnant women, although the CDC recommends a flu shot for everyone six months and older with a few rare exceptions.
Dr. Zimmerman says he recommends one of four newer vaccines for people at high risk for severe influenza, such as seniors or those with underlying health conditions.
Licensed only for seniors, a high-dose flu vaccine with the brand name Fluzone High Dose contains four times the amount of antigen or inactivated virus as a regular flu shot. There is also FLUAD Quadrivalent, an adjuvanted vaccine, which includes an ingredient that helps create a stronger immune response to vaccination.
For people 18 and older who are at higher risk of severe flu cases, there is Flublok Quadrivalent, which contains triple the amount of antigen. Finally there is the Flucelvax Quadrivalent approved for use in children and adults. “Each one has had a superiority over standard egg-based vaccines,” Dr. Zimmerman says.
Do I have the flu or Covid-19?
Distinguishing between Covid-19 and the flu will be nearly impossible without taking a diagnostic test, doctors say.
“There’s not going to be any obvious tipoff whether it’s the flu or Covid other than getting tested,” says
Peter Hotez,
co-director of the Center for Vaccine Development at Texas Children’s Hospital in Houston.
“If you feel sick, we’re going to have to start testing for both now,” he says. Antiviral drugs can help reduce the symptoms and severity of flu, but are more effective when started early.
Write to Sumathi Reddy at sumathi.reddy@wsj.com
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