Dr. Marcus R. Pereira, medical director of the Transplant Infectious Diseases Program at NewYork-Presbyterian/Columbia University Irving Medical Center and assistant clinical professor of medicine in the Division of Infectious Diseases at Columbia University Vagelos College of Physicians and Surgeons, shares why a second booster was recommended and what experts know about protection from prior infection.
What’s the rationale for authorizing a second booster?
I think multiple factors went into the decision. We know immunity starts to wane after four months or so, and the Omicron subvariant BA.2 appears more capable of breaking through our immunity. And then there’s the understanding that those over 65 and those who are immunocompromised were hardest hit by Delta and Omicron.
A recent Israeli study of a second booster also factored into the decision, even though it is not fully published yet. The study offered a second booster dose to people age 60 to 100 and then looked at mortality. After 15 days there was already a big difference in deaths and hospitalizations from COVID between the two groups. For those age 60 to 69, people with just one booster had a two-fold higher rate of death from COVID. And for those over 80, the rate was almost 10 times as high.
The FDA is taking into account BA.2 and what other variants may emerge next. The coming BA.2 wave could mimic what happened with Omicron, and older individuals and immunocompromised people will be hit hardest. In this case, a second booster is likely to provide added protection for these vulnerable groups.
Why limit the recommendation to people over 50?
A fourth booster does not seem to create much of a benefit when it comes to more severe outcomes for those who are younger.
This comes from another Israeli study, just published a few weeks ago in NEJM, that looked at the efficacy of a fourth dose of the vaccine in health care workers against Omicron. A second booster only provided a marginal benefit to those under 60.
The age 50 to 60 category, especially in those without health problems, right now is a gray zone. The data on efficacy of a second booster in this group is limited, so it’s hard to say what the benefit is. These individuals may do well with just one booster if they don’t have additional comorbidities. However, if cases are rising in their communities, then getting a second booster at this time may be of benefit.
Should I get a second booster now or wait?
Those in the age 50 to 60 category who are healthy and don’t have any additional comorbidities should talk to their doctors about when it would be reasonable to get the second booster, in particular in relation to rates of local transmission of the virus. This is because we now know that the effects of the vaccine wane after four to six months, so the timing is very important in order to maximize the benefits. It takes about a week for the effects of boosting to occur.
If you are immunocompromised or over age 60 or 65, I’d advise getting a second booster sooner rather than later, because the risks of COVID are still substantial.
Is a second booster dose safe?
These vaccines are very safe. Some transplant recipients have already received a fifth dose, and there hasn’t been any warning signal on multiple dosing. The recent NEJM study saw no safety issues.
If I’ve already been infected with Omicron, should I get a second booster?
The FDA authorization doesn’t mention this, but some experts suggest that an episode of COVID is potentially akin to a vaccine booster dose. If you’re otherwise healthy, you did well with Omicron, and you don’t foresee any risk factors coming your way—like you’re about to get chemotherapy or an organ transplant—it’s another situation in which you should talk to your doctor about whether it is reasonable to wait three to four months after COVID to get another booster.
The immunity benefit from getting Omicron will probably start to wane after four months. If there is a wave in the summer, like what happened last year with Delta, it is not clear that an Omicron infection from December or January would be a significant protective factor against a breakthrough infection, though it will probably offer good protection against severe disease, just as the first booster does after four to six months.