Two Studies Show Waning Immunity with Pfizer's COVID-19 Vaccine — But Don't Panic
While there are some folks currently eligible to receive a booster dose of the Pfizer-BioNTech COVID-19 vaccine (such as the immunocompromised and people 65 years of age or older), others remain in a waiting game until health officials give the green light. But in the interim, however, two new studies have seemingly confirmed what the pharmaceutical giant has said all along: Immune protection wanes from its two-dose vaccine, making the need for a third shot all the more critical as the fight against COVID-19 continues. (See: How Effective Is the COVID-19 Vaccine?)
Two new studies (one from Israel and one from Qatar) were published Wednesday in the New England Journal of Medicine, with researchers looking at antibody levels among Pfizer recipients within six months of receiving a second dose. The study from Israel analyzed antibody levels among 4,800 health care workers in the country, finding that antibody levels wane rapidly after the initial two doses of the vaccine, particularly among men, folks 65 years of age and up, and those with suppressed immune systems. The study was conducted over the course of six months between December 2020 and July 2021, with workers tested for antibody levels monthly after their second vaccination. Overall, it found "a significant waning" of the antibody-mediated immune response within 6 months after receipt of the second dose.
The Qatar study was a real-world analysis that looked at the rate of breakthrough infections in the nation — which has a highly vaccinated population, and most of whom received the Pfizer vaccine (the researchers note that between December 2020 and September 2021, over 907,000 people had completed the two-dose regimen). Researchers of the study found a similar dip in protection levels as the first study, noting, that "effectiveness reached a low level of approximately 20 percent in months five through seven after the second dose."
Still, the Qatar researchers found that Pfizer remained consistently effective in protecting recipients against COVID-related hospitalization and death, even with waning immunity. As of August 30, the study noted just 377 hospitalizations among those who had received one Pfizer dose and 106 among those who'd received two — which, reminder, was more than 907,000 people. The researchers also recorded 34 and 15 fatal COVID cases, respectively, which means being fully vaccinated still provides protection against serious illness, even as antibodies begin to wane.
If this sounds like seriously bad news, know that having this information is actually good news. How so? Well, it actually helps health officials determine the best course of action to prevent continued COVID-19 epidemics in vaccinated folks. (Read more: What Does a Positive Coronavirus Antibody Test Result Really Mean?)
FWIW, Pfizer itself last month presented data to the U.S. Food and Drug Administration that shows the efficacy of its vaccine wanes over time, and that the rates of breakthrough infections (i.e. when a fully vaccinated person develops COVID-19) are rising faster in individuals who were vaccinated earlier. But so far, according to the data presented, a third booster dose has been "highly effective" in protection against COVID-19 and its variants, which is why you should still plan to get a booster as soon as you're able. (This week, Johnson & Johnson announced it's formally seeking approval from the FDA for its booster shot.)
The Qatar study also accounted for real-world behavioral differences, noting "vaccinated persons presumably have a higher rate of social contact than unvaccinated persons," in addition to a possible "lower adherence to safety measures" (e.g. social distancing, masking up).
If you're still feeling uneasy, know that your vaccine is doing its job to keep you safe from the most serious effects of the virus. Laith Abu-Raddad, Ph.D., a co-author of the Qatar report who studies infectious disease epidemiology at Weill Cornell Medicine-Qatar, told Bloomberg that "protection against hospitalization and death is really strong and more durable than protection against infection." And yes, Abu-Raddad confirmed that a third Pfizer booster helps optimize your protection, so getting yours as soon as you're eligible is crucial. (ICYDK: This is who's eligible to receive a Pfizer COVID-19 booster shot as of now.)
So take a deep breath and know that, if you're fully vaccinated, standing at the ready for a booster, and still taking some precautions to reduce your germ contact, you're doing the best you possibly can right now.
The information in this story is accurate as of press time. As updates about coronavirus COVID-19 continue to evolve, it's possible that some information and recommendations in this story have changed since initial publication. We encourage you to check in regularly with resources such as the CDC, the WHO, and your local public health department for the most up-to-date data and recommendations.