Covid Vaccine Boosters: Which One Should You Get?

Short answer: any of them will help! COVID-19 immunity doesn't last forever, so it's important to find booster shots before the holidays are in full swing.

On October 21, 2021 the CDC officially announced that a large proportion of Americans were eligible to receive a COVID-19 vaccine booster.


While the list is fairly specific as it pertains to specific age groups or those with specific medical conditions or professions, the reality is that the vast majority of people who received their initial vaccine series will become eligible for the booster vaccine when enough time has passed from their initial shots.

Who Is Eligible?


The CDC has a complete up-to-date list of eligibility criteria here. In general, this includes anyone over the age of 65, anyone who is at higher risk of exposure from a profession working with the general public, and those who may be at higher risk of developing a severe form of the infection due to certain underlying medical conditions.


Among this list are relatively common conditions such as high blood pressure and diabetes, as well as being considered overweight which corresponds to a BMI greater than 25. Given that well over two-thirds of Americans have a BMI that falls into this range, this makes up a sizable group of people.


Another key criteria is timing.


While vaccines have universally been shown to reduce COVID-19 infections, lessen COVID-19 hospitalizations, and prevent COVID-19 related deaths, studies have shown that while protection against hospitalization remains strong several months after vaccination, protection against getting a COVID-19 infection gradually declines during the same time period.


In a recent study of US veterans, efficacy of the vaccines over a 6-month period dropped to about 54% overall by the end of the study period, and the breakdown across the specific vaccines’ efficacy dropped to 64% for Moderna, 50% for Pfizer, and 3% for J&J.


This means that “breakthrough infections” could potentially become more frequent as time goes on, especially with the highly contagious Delta variant still present.


Why aren’t we seeing more people getting sick now?


This is probably because the vaccines have helped us get infection rates down to such a low level that there is just less chance of coming across someone else who is sick, but this won’t last forever. Vigilance is key in preventing another rise in COVID-19 infections. For these reasons, the CDC and FDA have recommended booster vaccines 6 months after the second dose of the mRNA vaccines from Pfizer and Moderna, and 2 months after a single dose of the J&J vaccine.


For those who have received the initial Pfizer or Moderna vaccine series, you may notice that the CDC uses somewhat ambiguous language regarding whether eligible patients “should” or “may” get a vaccine depending on their eligibility criteria.


For the latter group the advice is to make a personalized decision based on the individual risks and benefits of getting the vaccine. I am always happy to have this discussion, as it is primordial with any medical decision that the benefits outweigh the risks.


Spoiler alert on this one: I have yet to come across a patient where the risks of vaccination and of greater vulnerability to COVID-19 infection outweigh the benefits of getting vaccinated. So if you are on the fence, let’s talk!


For those who have received the single dose of J&J vaccine, the recommendation is for everyone aged 18 and over to get the booster vaccine dose. An extra dose of J&J has been shown to be more effective than the single shot, and as data is released the two-shot regimen may potentially rival the mRNA vaccines in terms of overall efficacy.


Which COVID-19 Vaccine Boosters Are Available?


Currently, any of the COVID-19 vaccines authorized in the US (Pfizer, Moderna, and J&J) are available as a booster shot. The CDC has authorized a “mix and match” policy where anyone can receive any vaccine no matter which one you received in the past.


Many of us didn’t have a choice when we got the first shot, so now that we are fortunate enough to have the choice, it makes sense to consider which is the most effective. The CDC did publish one study which compared the three vaccines’ efficacy for reducing hospitalizations and found that Moderna was most effective at 93%, Pfizer at 88%, and J&J at 71%.


However, when deciding which vaccine booster to get, it’s a little more complicated than that. We have more and more data concerning the initial series of vaccines, but how is this going to change with the third dose?


This data does not mean that a third dose of Moderna for people who received Moderna will necessarily be more effective than a third dose of Pfizer for people who received Pfizer. And it doesn’t address the question of vaccine efficacy when shots are mixed-and-matched. More and more information is trickling in, but research studies are very complex undertakings. Comparing different studies with different populations of people in different regions with different variants of the virus in circulation can be a challenge.


So far, what we do know from the studies that have been done is that receiving the same vaccine or a different vaccine as a booster both help to increase antibody levels. However, we’re not really able to determine the effectiveness of specific vaccine combinations based on antibody levels alone.


In terms of real-world data, we know that receiving the same booster shot as the initial vaccine series (Pfizer in Israel) increases vaccine efficacy against getting a COVID-19 infection, but there’s no data yet on vaccine combinations. Interestingly, some recent data has indicated that there could be a benefit to mixing and matching.


Since each vaccine is slightly different, the body gets a different “view” of the virus and could potentially develop a more robust immune response. For now, the best strategy is not clear. The real-world data will come as more Americans get their booster vaccines.


Okay So...What Should I Do?


If there is one thing to take away from all of this, it’s that vaccine boosters help the body mount a stronger defense, whether they are the same as the initial vaccine or not. They have also been shown to be very safe, with reports of severe side effects remaining extremely rare.


Given that the efficacy of the initial vaccine series is waning every day, there is no reason to wait more than necessary to get your booster shot. So what should you do? 


Go out and get your booster today – no matter which one!


Every day that goes by without having maximum protection is a day that you could potentially be exposed to COVID-19 and become infected despite having been vaccinated. And every new infection runs the risk of spreading the virus to friends, colleagues, family members, or strangers, prolonging the pandemic and causing more people to get sick.


Breakthrough infections are real, and while the vaccines help prevent serious complications, I have found a few things to be universal in the patients I have seen: no one wants to be sick, no one wants to pass the virus to their loved ones, and no one wants to be isolated at home for 10 days when they’ve already done what they could to protect themselves and others.


The best way to continue staying safe and preventing infection is by getting your booster shot today!


At Radish Health we are offering COVID-19 booster shots at many of our workplaces. I’d be happy to talk with anyone about questions you may have and how we can arrange for you to get your booster dose and stay safe this holiday season!

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