Certain vaccines, such as the tetanus shot, need boosts every decade to boost the immune system. Some, like flu vaccine, have to be given every year because the virus changes so much.
Will something similar happen with the COVID-19 vaccines?
“Immunity will definitely fade,” said Dr. Paul Offit, an infectious disease doctor and director of the Vaccine Education Center at Philadelphia Children’s Hospital, said TODAY.
“The question is, does it fade to the extent that you are not protected from serious diseases?”
Researchers can know within about six months whether boost shots are needed, he added.
“Unfortunately, like so many others in COVID, this is one of those things where we will not really know when we are going to know until we have evidence that things are no longer working,” said Dr. Daniel Kuritzkes, head of the division, said. infectious diseases at Brigham and Women’s Hospital in Boston and professor of medicine at Harvard Medical School.
“We need the accumulated experience over time to know what it all means.”
For now, the shots are working well, with Offit calling them ‘powerful immunogens’. Both he and Kuritzkes predicted that the immunity given by the COVID-19 vaccines would last two to three years.
What is now known:
This month, Pfizer and BioNTech said trial data show their vaccine still offers high levels of protection against COVID-19 six months after the second dose.
Moderna also cited a study showing ‘persistent antibodies’ six months after the second dose of the vaccine.
Both vaccines are extremely effective in the real world and reduce infections by 90% in people who have been fully vaccinated, the Centers for Disease Control and Prevention reported in March.
Studies are now underway to measure immune responses over six months.
How will we know that boosters are needed?
An increase in breakthrough COVID-19 infections – which occur in people who are vaccinated but still become infected when exposed to the virus – would be a warning sign, Kuritzkes said.
People in vaccine trials are monitored by the CDC and other groups on a long-term basis. Currently, a small minority of them are still infected, 4-5%, but as the number increases, this is a reason to recommend booster vaccinations for COVID-19.
What about COVID-19 variants?
It is possible that a separate new vaccine will be needed if a COVID-19 variant that is resistant to current shots emerges, Offit and Kuritzkes said.
This has not yet happened, but in a recent survey among 77 epidemiologists from 28 countries, two-thirds believed that it would take a year or less before the new coronavirus would mutate to the extent that most first-generation vaccines would become ineffective. new or modified shots. The survey was conducted in February and March 2021 by the People’s Vaccine Alliance, a coalition of organizations and activists.
“We may have cycles where we need to continue to boost people – either to boost them with the original vaccine, which gives you enough antibodies to flush to the variant, or to develop a vaccine specific for one or more more of the variants, “said dr. Anthony Fauci said on MSNBC last month.
‘The only problem with the latter is that otherwise you can play a mole with the variants, because we have many different variants … what you really need to do is get a vaccine that is strong enough and broad enough that it all the other variants will overlap. “
This is what researchers are working on to prevent recurrent vaccination, Fauci added.
Pfizer and BioNTech said trials indicated that their vaccine was effective against a coronavirus variant that first appeared in South Africa.
In March, the National Institutes of Health said it had “begun testing a new coronavirus vaccine from Moderna ‘designed to protect against the variant’ out of abundance of caution ‘should an updated vaccine be needed. ‘Fauci explained.
“If it turns out that we need to better adapt the vaccine to these emerging variants, another round of vaccination may be needed with a vaccine that is a closer match,” Kuritzkes said.
“It will be a bit hybrid, because it will increase the antibody level … and increase the specificity of the immune response.”
Would new clinical trials be needed?
Not like before. In February, the U.S. Food and Drug Administration said modified COVID-19 vaccines against variants may be granted without the need for lengthy clinical trials.
The flu shot is needed every year – would it be the same for the COVID-19 vaccine?
Not likely, since the new coronavirus does not mutate as fast as the flu virus.
“Flu is in its own league,” Offit remarked. “This virus is actually pretty slow in mutation.”
Still, lifelong protection against the COVID-19 vaccine will not happen, he predicted.
Other coronaviruses cause colds and it is clear that colds cannot occur a few years later if you get another one. This is the main reason to think that a booster shot may be necessary, Kuritzkes said. But at the moment, boosters are unlikely to be needed in the next few years, he added.
How would a booster be rolled out?
Offit believed it would be similar to the explosion of the vaccine, with the oldest and most vulnerable patients as well as health professionals being preferred for the shot.
Kuritzkes said it would depend on the provision of vaccines.
“People will retain a certain amount of immunity, so there will not be the same urgency and madness to boost everyone in a very, very small amount of time,” he noted. “But I think we’d like to see everyone vaccinated again.”
