Coronavirus Questions
Can COVID-19 vaccines be mixed and matched?
Health officials say both doses should be of the same kind.
The COVID-19 vaccines rolling out in the United States, the United Kingdom and other parts of the world so far require two shots given a few weeks apart.
In the U.S. where vaccines from Pfizer and Moderna are being distributed, health officials say the two aren’t interchangeable even though they’re made similarly.
In “exceptional situations” when the same kind isn’t available or if it’s not known what was given for the first shot, the U.S. Centers for Disease Control and Prevention said in recently updated guidance that it’s OK to give whichever vaccine is available for the second shot.
The agency noted that the recommendations could be updated as more information becomes available, or if other types of vaccines are authorized for distribution.
The CDC also said the doses could be given up to six weeks apart if it’s not possible to give the second dose at the recommended interval. For the Pfizer vaccine, the second dose is recommended three weeks after the first. The second shot of the Moderna vaccine is supposed to be four weeks later.
“After posting our initial guidance, we received feedback that some flexibility in our language might be helpful,” CDC spokeswoman Kristen Nordlund said in an email.
The original recommendations on doses and timing should still be followed, but the agency didn’t want its guidance “to be so rigid that it creates unintended barriers,” Nordlund said.
Officials in England, where shots by Pfizer and a different type of vaccine by AstraZeneca are available, also say the doses should be consistent. But in rare cases, they say a mismatched dose is better than partial protection.
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How are experts tracking variants of the coronavirus?
Scientists are scanning virus samples taken from infected people to look for mutations, through a process called genome sequencing. It’s the same method researchers have been using for years to study bacteria, plants, animals and humans.
Around the world, researchers have sequenced more than 500,000 genomes of the COVID-19 virus to date.
Viruses can mutate as they make copies of themselves after infecting a person. By sequencing virus samples over time, scientists can look for recurring changes in the genome.
“If we don’t know these things, we’re running blind,” said Sara Vetter, assistant lab director for the Minnesota Department of Health.
Most mutations are meaningless, but others can make a virus more contagious, deadly or resistant to vaccines and treatment. Health experts are primarily concerned about three variants first detected in the United Kingdom, South Africa and Brazil. They seem to spread more easily and research is underway to see if they cause more serious disease.
Evidence suggests that current vaccines still work against the variants though perhaps not as well against a mutated version that first appeared in South Africa.
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Can I take painkillers before or after a COVID-19 vaccine?
It’s best to avoid them, unless you routinely take them for a medical condition. Although the evidence is limited, some painkillers might interfere with the very thing the vaccine is trying to do: generate a strong immune system response.
Vaccines work by tricking the body into thinking it has a virus and mounting a defense against it. That may cause arm soreness, fever, headache, muscle aches or other temporary symptoms of inflammation that can be part of that reaction.
“These symptoms mean your immune system is revving up and the vaccine is working,” Dr. Rochelle Walensky, director of the U.S. Centers for Disease Control and Prevention, said in a recent news briefing.
Certain painkillers that target inflammation, including ibuprofen (Advil, Motrin and other brands) might curb the immune response.
