Experts have gone back and forth about the necessity of a third dose for the COVID vaccines approved for use in the U.S. While some experts believe a booster shot is necessary to protect against the Delta variant and mitigate waning efficacy, others say the vaccines are sufficiently protective without an additional dose. Now, Pfizer has released new data that shows a third dose of its COVID vaccine "strongly" boosts protection against the Delta variant, making a case for another shot.
According to the new data Pfizer shared on July 28, a booster shot of its vaccine could afford protection beyond what the standard two doses create. The data suggests that people aged 18 to 55 who get a third dose see their antibody levels against the Delta variant shoot up more than five-fold from what they were after the second dose. People aged 65 to 85, meanwhile, saw an even more significant spike in antibodies after a booster shot. A third dose gave people in this age bracket more than an 11-fold increase in antibodies compared to what they had following their second dose.
Researchers wrote that there's "estimated potential for up to 100-fold increase in Delta neutralization post-dose three compared to pre-dose three." Not only would a booster shot help protect against the Delta variant, but it could also reinforce protection against other strains, Pfizer says. According to the data, antibody levels against the previously dominant COVID variant and the Beta variant, which was first identified in South Africa, also notably increase after a third dose.
Pfizer's new study comes after research that seems to suggest two doses might not be enough to protect against the spread of the Delta variant. Per The Wall Street Journal, a July 5 study out of Israel found that the Pfizer vaccine is less effective at protecting against the Delta variant than other strains. The data was collected during a massive outbreak caused by the variant. According to Israel's Health Ministry, the Pfizer shot was 64 percent effective against COVID infection during the outbreak. Previously, the vaccine was shown to be 94 percent effective against infection. However, even as Delta spread rapidly, the Pfizer vaccine was still 94 percent effective at preventing severe illness, a 3 percent reduction from the clinical trials.
Additionally, Pfizer announced on July 8 that a study from the Israel Ministry of Health found that vaccine efficacy "in preventing both infection and symptomatic disease has declined six months post-vaccination." Although the vaccine continues to be effective at preventing serious illness beyond six months, the company wants to get a third dose approved. The announcement said the company would be seeking authorization for a booster shot of its COVID vaccine in August.
Moderna and Johnson&Johnson also have their eyes on booster shots of their respective vaccines. During the Forbes Health in Action Summit on June 8, Moderna CEO Stéphane Bancel said that the current vaccines in the U.S. won't be enough to provide immunity against the virus long-term, especially as new variants emerge and spread. He feels that boosters will be needed in the near future, but he's unsure of when.
"I think for next fall, we as a community should rather be two months too early boosting than two months too late. And there is no way to precisely know when people should be boosted," Bancel said. "Given we are all evolving with very uncertain data with a brand-new virus, I think being cautious and boosting early is going to be wise for that pandemic phase in the boosting phase of 2022 or late 2021."
Johnson&Johnson is in a slightly more precarious situation, as its vaccine has not proved quite as effective at preventing symptomatic infection as the others. Angela Rasmussen, PhD, a virus expert and research scientist with the Vaccine and Infectious Disease Organization (VIDO), has urged anyone who got the Johnson&Johnson vaccine to consider getting a booster shot as soon as possible. "I encourage you to talk to your provider about whether this is something you should think about," Rasmussen wrote on Twitter on June 22. "If you live in a community with overall low vaccination, I'd suggest you strongly consider doing so." She added that it may be wise to get a booster shot of Pfizer or Moderna rather than another dose of Johnson&Johnson.