How Long Does COVID-19 Vaccine Immunity Last?

What experts know about immunity after vaccination and whether booster shots will be necessary.

Clinical trials and real-world conditions have proved that vaccines protect against COVID-19. But the question remains: How long will vaccine immunity last?

“Recent studies have shown promising results that suggest immunity may last for longer than originally expected, but time and additional data are needed to determine exactly how long,” says Dr. Sharon Chacko, medical director at the Farrell Community Health Center at NewYork-Presbyterian’s Ambulatory Care Network and medical director of COVID-19 immunizations in the Division of Community and Population Health.

To learn more about this evolving issue, Health Matters spoke with Dr. Chacko, who is also an assistant professor of medicine at Columbia University Vagelos College of Physicians and Surgeons, about vaccine immunity — how long it may last, if some vaccines offer longer protection against COVID-19, and whether booster shots may be needed down the road.

Dr. Sharon Chacko

Dr. Sharon Chacko

Health Matters: What do we know about how long immunity lasts after vaccination for COVID-19?
Dr. Chacko: Initially, we knew immunity lasted at least six months after vaccination, because the first trials had six months of data at that time. However, these studies are ongoing, and we now know that immunity actually lasts longer than we anticipated. At this point, we don’t know for sure how long it will last, but we do know that it is even longer than six months, which is exciting.

How do researchers assess immunity?
The participants who are in these studies are monitored regularly after vaccination. They receive regular blood tests to have their antibody levels checked and are also checked for breakthrough infections — meaning people who are infected with COVID-19 even after vaccination. Using those two factors and others, researchers are able to obtain more information about the expected duration of immunity.

Some sources state that immunity may be higher in people who have had COVID-19 and later got vaccinated. Is this true?
There has been some suggestion of that. The idea is that people who have had COVID-19 build a natural antibody response and then subsequently, when they are vaccinated, that vaccination builds upon the initial immunity to create an even larger immune response.

That being said, the CDC recommends everyone — even people who were infected with COVID — get vaccinated, because we do not know how long one is immune after recovering from COVID.

Are there certain types of vaccines that provide longer-lasting immunity than others?
A recent Nature study demonstrated that after the mRNA vaccines, people had very long-lasting immunity. They found that even up to 15 weeks after the first vaccination, participants had really active germinal centers (where immune cells are developed and trained in the body). This suggests that immunity from mRNA vaccines may last much longer than we originally anticipated.

There has not been a comparable study for the Johnson & Johnson vaccine, so we cannot assert if the same effect would be present. It should be noted that there’s an important distinction between real-world efficacy as compared to laboratory analysis of things like antibody levels or immune cell responses. But the good news is that there are several studies going on right now which are looking at all of these different factors.

What are booster shots and how do they work?
For some vaccines, as time goes on, immunity decreases, and so a booster shot refreshes the immune response. An example of this is the tetanus shot, which you have to get every 10 years to ensure continued immunity.

“We don’t know for sure how long immunity will last, but we do know that it is even longer than six months, which is exciting.”

— Dr. Sharon Chacko

Will we need COVID-19 booster shots?
Pfizer, Moderna, and Johnson & Johnson are all investigating the use of boosters. There are two scenarios in which the use of boosters would be necessary: If there is evidence that immunity is decreasing at some point after vaccination (which is what we see with tetanus and other vaccines that commonly require a booster), or if there are new variants that are emerging that the existing vaccines do not respond to. According to the Advisory Committee on Immunization Practices (ACIP), we don’t have any data to suggest that either of those two scenarios are at play.

Currently, we have found that the vaccines continue to provide immunity against known variants. The CDC and FDA released a statement advising that those who have been fully vaccinated do not need a booster at this time. They reiterated that any decision regarding boosters must come from a science-based, rigorous process which considers laboratory, clinical trial, and cohort data. If the science shows boosters are needed, we are prepared.

Who might need booster shots more than others?
That’s exactly what several ongoing studies are trying to determine. One theory is that those with compromised immune systems might require a booster shot in order to mount a larger immune response. That’s not something that experts have been able to conclude just yet, but that’s part of what these studies are trying to determine: if a booster were needed, who should receive it, and when.

What do we know for sure?
There are three important things we know for sure:

  • We know that the vaccines are highly effective.
  • Areas with higher vaccination rates also have lower incidence of COVID-19 and a decreased rate of COVID-19 hospitalizations and death.
  • The vaccines continue to demonstrate efficacy even against the newer variants which have emerged since the initial vaccines were developed, such as the Delta variant. We know that areas where there are higher vaccination rates also have a lower incidence of variant strains, keeping everyone safer.

One thing we can all do is get vaccinated and encourage the people in our lives to also get vaccinated. Vaccination provides individual immunity, and as more people are vaccinated, we stop the spread of COVID-19, which means fewer opportunities for the virus to mutate, and thus slow the emergence of new variants.

Sharon M. Chacko, M.D., is a family medicine physician and the medical director at the Herman “Denny” Farrell, Jr. Community Health Center at NewYork-Presbyterian’s Ambulatory Care Network and an assistant professor of medicine in the Center for Family and Community Medicine at Columbia University Vagelos College of Physicians and Surgeons. Dr. Chacko has been a medical lead for NewYork-Presbyterian’s COVID-19 vaccination efforts and served as medical director at the vaccination site established by NewYork-Presbyterian at The Armory. She is now medical director of COVID-19 immunizations in the Division of Community and Population Health.