Reading: End Your Booster Confusion: Facts & Answers for Women 40+

When COVID-19 boosters were first approved in September, the federal government’s vague guidelines left many of us confused about whether we were eligible. Now that the US Centers for Disease Control (CDC) is urging all adults to get booster shots, it’s less a question of who should get a booster, and more a question of which one to get. 

The emergence of the Omicron variant — the highly infectious new strain recently identified in South Africa — prompted the CDC to strengthen its booster recommendations this week. Though the FDA authorized the Pfizer, Moderna, and Johnson & Johnson boosters for all adults in mid-November, the CDC’s guidelines initially stated that adults over 50 and in long-term facilities should get a booster, and that adults 18-48 may get a booster, depending on their risk. But as the Omicron variant spreads globally, the CDC has changed its tune, and now includes all adults in the should category. 

But which booster should you choose? Though recent studies suggest that mixing and matching vaccines may provide additional protection, there is still little guidance on who should get what. A rise in breakthrough infections have made some question whether getting a booster is even worth it (hint: it is).  And while public health experts argue that the advent of the Omicron variant highlights the urgency of getting vaccinated and boosted — it also raises more questions, such as, will the vaccines even work against this newly mutated strain? Here, epidemiologist David Banach, MD, PhD, Head of Infection Prevention at UConn Health and Associate Professor of Medicine at UCONN School of Medicine provides some answers for women 40+.  

CoveyClub: Now that the CDC recommends COVID-19 boosters for all adults, the question of who should get boosters is less confusing: Those who received the J&J shot are advised to get a booster when they are at least two months out from their vaccination; those who received Pfizer or Moderna (mRNA), when they are at least six months out from their second shots. But when is best? Right at two or six months, to be sure you don’t let your immunity wane? Or a little further out, so that your immunity lasts longer? 

Dr. Banach: If you had the J&J vaccine and you are past the two month point, that’s the appropriate time. And if you had an mRNA vaccine — given that we are still seeing high amounts of transmission of the virus in the United States — once you get past the six month interval, it’s time to get the booster. Boosters are especially important for people over 65 years and those over 50 years with medical conditions that put them at high risk for severe COVID.

CoveyClub: Are there any studies yet indicating how long the booster shots last? 

Dr. Banach: We don’t have much data on the durability. They do seem to be holding up well for several months based on data from Israel, who rolled out the vaccines sooner, but that’s an area of active study. In the weeks and months ahead we will learn more.

CoveyClub: Is it true that the COVID-19 boosters improve immunity within days? And if so, would you advise people to schedule a booster before traveling — or gathering — for the holidays, so that they are more protected? 

Dr. Banach: Considering that we’re at a point where there are still high levels of virus circulating in the community — and given the possibility for an increase in transmission with the holidays coming up — my general guidance is to receive a booster as soon as you become eligible. We don’t have an exact number of days per se where you get protection, but as soon as you get the booster you start that process of generating antibodies and boosting those levels. So you get that added protection very early on. 

CoveyClub: The FDA is allowing people to mix their vaccines; in fact, preliminary results from a National Institutes of Health “mix and match” study found that recipients of the J&J single-dose shot who received a Moderna booster saw their antibody levels rise 76-fold in 15 days, compared with a 35-fold increase after a Pfizer booster and only a four-fold increase after a second dose of J&J. Based on these findings, should people with the J&J vaccine assume that a Moderna booster would offer the greatest protection? 

Dr. Banach: I think there are a few things to think about. That mix and match study was relatively small and also included a full dose of Moderna, which is not the dose being offered for boosters [the Moderna booster is a half dose]. There is data to support the safety and efficacy of using an mRNA vaccine as a booster after the Johnson & Johnson; some of that is actually drawn from experience with the Astrozeneca vaccine, which uses the same technology as J&J. And there may be a difference between the different mRNA vaccines as boosters for those who received J&J, but at this point, we can’t draw a definitive conclusion about preferentially choosing one booster dose over another. There will be some individualized decisions, and having a conversation with your physician for specific recommendations relating to your own circumstances is important. 

CoveyClub: According to the J&J data, a second shot brings protection against moderate-to-severe COVID-19 up to 94 percent, bringing it up to a similar level of immunity provided by the first two shots of the Pfizer and Moderna vaccines. So any booster is better than no booster, right? 

Dr. Banach: Absolutely. The J&J can be boosted by either mRNA or a second J&J — both strategies seem to confer a high level of protection. 

CoveyClub: What about those who have received the Moderna or Pfizer vaccine? Are they better off sticking with the brand they received for a booster? Or mixing and matching? 

Dr. Banach: Again, I think at this point the data on mixing and matching is limited, so it’s difficult to make a preferential recommendation to mix and match. The large studies that looked at boosters looked at people who got the same booster as the initial vaccine, so that’s where the data set lies. We can’t say one strategy is better than the other, which is why the CDC in its guidance allows for mixing and matching but doesn’t recommend any specific strategy. 

CoveyClub: The mix and match study looked at antibody levels, but isn’t there another measure of immunity? Don’t the vaccines also boost the levels of immune cells primed to attack the virus? 

Dr. Banach: The antibodies are often what’s measured because they are the easiest and most straightforward to measure, but they don’t tell the whole picture. There are other components of the immune system, specifically T cells and B cells, that also have important roles in providing protection and that are stimulated by vaccines. That’s why even if you get your antibodies checked and no longer have antibodies to COVID-19 detected, you may still be protected. 

CoveyClub: While we’re on the topic of antibodies, is there any benefit to getting an antibody test to confirm that your immunity has waned — and determine whether you “need” a booster yet — before getting the additional shot? 

Dr. Banach: I’ve been discouraging testing antibodies prior to boosters, first, because we don’t have a clear understanding of what antibody level provides enough protection to prevent infections. The other question pertains to the durability of the antibody: An individual who has a high level of antibodies at one point in time may have waning immunity in the coming days and weeks that would not be detected in a single antibody measurement. The information gathered from antibody measurements is limited, so I generally don’t use those in making decisions — nor is there public health guidance that supports using antibody tests in that way.

CoveyClub: All three vaccines have been linked to rare but concerning adverse effects: In a small number of cases, the MRNA vaccines could cause myocarditis or pericarditis among younger individuals; the J&J vaccine has been linked to rare cases of a serious blood clotting disorder as well as Guillain-Barre syndrome. Which populations are most at risk for these complications, and should certain populations avoid certain boosters based on these risks?

Dr. Banach: There are some individual circumstances to think about with regard to specific boosters. That’s why I recommend having a discussion with your physician — and weighing the pros and cons of the different options based on your own medical background and your age — to determine whether one booster would be more suitable for you than another. These adverse effects have been seen more in certain age groups or cohorts. The heart inflammation linked to the mRNA vaccines tended to occur in younger male populations; the blood clotting in the brain after the Johnson and Johnson vaccine was seen in younger females. (Guillain-Barre syndrome didn’t show a significant difference among different populations.) They were all, in the big picture, very uncommon, quite rare events. 

It’s important to understand that some of these symptoms, notably the heart inflammation, as well as an increase in blood clotting, are seen after COVID-19 infection at a significantly higher rate than they occur after vaccine.

CoveyClub: Is there any data on whether any of the three vaccines — and boosters — are less likely to produce the more minor side effects, like fatigue, soreness at the vaccination site, and overall achiness? I’ve heard that people who got the Moderna shot were more likely to report side effects than those who got Pfizer. But would this hold true for the half-dose booster?

Dr. Banach: Based on the clinical trials the degree of side effects tend to be slightly higher with Moderna initial series when compared to the Pfizer and J&J vaccines; in terms of boosters, the side effect profile is generally similar for the booster doses as for the initial vaccination (two doses of Pfizer and Moderna vaccines and one dose of Johnson & Johnson). For the Moderna vaccine, the rate of adverse events seems to be lower with the half-dose, currently authorized as the booster dose, than when the full dose is given as the third dose after an initial vaccine series. There is ongoing data collection through the current surveillance system evaluating these questions about side effects in the real world. 

CoveyClub: What is the difference between a “booster” and a “third” or “additional”  dose?  When you go onto certain websites to sign up for boosters — CVS or Walgreens, for example — you are offered a choice of a booster or an “extra” (or “additional”) dose. How do you know which one to sign up for? 

Dr. Banach: When we talk about an additional dose, that’s not referring to a six month booster, that’s referring to immunocompromised individuals who are advised to get a third dose. That was authorized a couple of months ago for patients who received two shots of either Moderna or Pfizer, [for] at least 28 days after their second dose. For those who were vaccinated with Moderna, the full dose of Moderna is given for the third dose, [as opposed to a half dose for the booster]. A full dose of Pfizer is given for both the booster and the additional dose. The third dose is essentially considered part of the initial vaccine series for the immunocompromised population. So people who are immunocompromised should receive a third dose as part of their initial vaccination series, whereas those who aren’t receive a booster dose 6 months out to boost up their waning immunity. (The immunocompromised would still qualify for booster 6 months later, after their third dose.)

CoveyClub: Even as the effectiveness of the various vaccines in preventing infection with COVID-19 wanes — which is why we’re seeing some breakthrough infections — do all three continue to provide protection against hospitalization and death, even two months after a single J&J shot and six months after two shots of either mRNA vaccine? 

Dr. Banach: In the general population, they seem to be providing a high level of protection against severe illness, hospitalization and death, even months out from the initial vaccination series. But the vaccine seems to be waning more rapidly in the immunocompromised and in older individuals, as their immune system is not as robust as that of younger individuals. (This is not unique to the COVID-19 vaccine: For example, for the flu vaccine, we give a higher dose for individuals 65 and older because they need more stimulation to get a protective level of immunity from the shot.) That’s why older individuals were in the initial group for which boosters were recommended. But I think there’s benefit for boosters to be brought into the broad population, as the boosters have been demonstrated to reduce not only severe infections and hospitalizations but also transmission. The Johnson & Johnson vaccine recipients seem to have a significantly higher protection after the second dose from all severe outcomes including hospitalization. Many interpret this as suggesting this vaccine should really be considered a 2-dose vaccine. 

CoveyClub: Is it true that studies suggest that vaccination confers greater protection against COVID-19 than having the illness itself? In this case, should even those who have been fully vaccinated and had COVID (either before vaccination or with a breakthrough case) still get boosters? 

Dr. Banach: That is true, some studies do demonstrate that vaccine-induced immunity may be more protective than “natural immunity.” The challenge with infection-induced — or natural — immunity is that there is probably a lot of variability between individuals. One who had a very mild infection may develop less immune response than someone with a very severe infection. Although we are still learning more about those who have had a COVID-19 infection after the initial vaccine series, individuals in this situation are still eligible to receive the booster. 

CoveyClub: How long should you wait after having breakthrough COVID before getting a booster? 

Dr. Banach: The general recommendation is that individuals receive boosters based on the time from their initial vaccine series as opposed to taking into consideration whether they’ve had infection at some point. You would want to wait for someone to be fully recovered from their post-vaccine infection, and have completed their isolation period so that they are not contagious. Those who received treatments for COVID-19 such monoclonal antibodies or medications that can affect the immune system may need to wait longer before receiving a booster dose and should discuss this with their personal physician for specific guidance. 

CoveyClub: Does the recent appearance — and seemingly rapid spread — of the Omicron variant provide even more of an impetus to get boosted as soon as possible? Do we even know if the boosters work against the Delta and Omicron variants? Should we expect them to work against other variants that develop going forward? 

Dr. Banach: Without additional data, it’s difficult to determine the vaccine effectiveness against the Omicron or other future variants, but the booster provides additional protection against the Delta variant, the current predominant variant, and against the variants we’ve seen so far.

CoveyClub: If you’ve been vaccinated and boosted, can you feel pretty safe about gathering in groups? Is it still necessary to take precautions like wearing masks in certain settings? 

Dr. Banach: The boosters do make things safer in terms of preventing illness. But when deciding about additional protective measures, such as masks, I would encourage people to consider not only their own personal risk, but also the risk of their family members and other close contacts, and the potential that you could spread the virus to them. Being vaccinated, including a booster dose if eligible, doesn’t only protect you, it reduces your ability to spread it to other people. We do know that breakthrough infections are less contagious to other people and the shedding of the virus seems to be shorter in vaccinated individuals who develop a breakthrough infection — probably even more so after a booster. But the safest of circumstances is when everybody in a group is vaccinated. When there is a mixed population of vaccinated and unvaccinated people, masks add another level of protection. Highly immunocompromised individuals also benefit from additional preventive measures such as masking and physical distancing. 

CoveyClub: What would you say to your patients who are hesitant about getting vaccines? What about vaccinated individuals who are hesitant to get boosters? 

Dr. Banach: With regard to people who haven’t gotten vaccinated yet: There are more and more data supporting the importance and safety of the vaccines — at this point they’ve been given to many millions of individuals, reinforcing the confidence we have in their safety and efficacy. The initial vaccine series provides and continues to provide high levels of protection against hospitalization and severe illness and mortality. We have seen breakthrough cases in people who were fully vaccinated with the initial series, though the overwhelming percentage of them tend to be relatively mild. The boosters have the added benefit of protecting against mild infections and preventing transmission by reducing the infectiousness of those who do develop breakthrough infection. It’s an added level of protection. [And finally,] the boosters provide a high level of protection against the Delta variant, which is the primary variant circulating in the United States at this time.