SAN DIEGO (KGTV) - As millions of people get their COVID-19 vaccine booster shot, many wonder if this will become a yearly necessity. But experts agree that the question does not have a simple answer.
"We know that COVID-19 is around to stay for a while," says Suzanne Shea, the VP of System Pharmacy at Sharp Healthcare. "And there is definitely some sense based on the research that we're seeing now that it would become on some routine basis. We just don't know what that is yet."
Some experts have tried to answer, but few have found a consensus.
In August, CDC Director Dr. Rochelle Walensky told CBS News that she does not think a yearly COVID booster will be needed.
"It does look like after this third dose, you get a really robust response," she said in the interview. "This virus has been humbling, so I don't want to say never, but we are not necessarily anticipating that you will need this annually."
But the CEO of Pfizer disagrees. That same month, CEO Albert Bourla told Business Insider that "the most likely scenario is we will be needing annual re-vaccination, as we do with the flu vaccine."
Shea says these disagreements are expected because doctors can only take what she calls "educated guesses" based on the limited data we've seen so far.
But she reminds everyone who asks that we still have a lot to learn.
"In very healthy people, the immunity could last much longer than somebody who is less healthy," Shea says. "That's still yet to be determined."
Meanwhile, researchers at the La Jolla Institute for Immunology are trying to find specific answers about boosters and protection against COVID.
In addition to an ongoing study about COVID-19 immunity, they've started two new studies. One looks at how much booster shots increase immune responses in both antibodies and T-cells. The other study will examine whether or not breakthrough COVID-19 infections boost immunity and serve as a substitute for a booster shot.
RELATED: La Jolla institute takes comprehensive look at COVID-19 vaccine immunity
Dr. Alessandro Sette is leading some of the research. He told ABC 10News that the answers are complicated because no one has identified a threshold for antibody or cell levels that equates to protection.
Dr. Sette also says that level depends on if we want the vaccine to give immunity from infection or just protection against severe disease.
"There could be that there is a level of immunity that is perfectly sufficient to prevent the severe disease, but it may not be sufficient to prevent an infection," Dr. Sette says.
Booster shots have been part of medicine for decades. Some people get a flu shot every year. The tetanus vaccine requires a booster shot every ten years. For other diseases, like hepatitis, a three-shot regimen is enough to confer life-long protection.
But those vaccines have been studied for years. The COVID-19 shot has only been around for a couple of years, and booster shots started within the last two months.
Dr. Sette thinks we'll need another 6-8 months of data before getting any real answers on how long protection lasts after a booster shot.
Still, he thinks the studies that have been underway on the initial doses of vaccines could offer hope that continued boosters may not be necessary.
"From what we've seen, the vaccination does induce memory responses," Dr. Sette says. "Memory responses can stick around for years. So I think there is reason to be moderately optimistic here."
Age is another factor in booster durability. COVID has a more severe impact on the elderly and immunocompromised, so some doctors think people in those categories may need additional boosters. Conversely, they say people who are not in high-risk groups may not.
For kids who are just starting to get their first shots, it could be more than a year before we know if they'll need a booster at all.
"How long does their immunity last as you go into adulthood versus somebody who's an adult today?" Shea asks. "There's a lot more research that needs to be done and is being done."
The length of the Pandemic also plays into this. The longer it lasts, the more likely we will see another variant that could need additional shots. And more cases mean a higher likelihood of transmission.
Doctors say if that were the case, we might need a higher immune level of protection.
That's why many say it's more important to make sure everyone that should get a shoot or a booster gets it now to bring the Pandemic under control, and then we can worry about additional doses in the future.