Pfizer's CEO Says Efficacy Drops This Much After 4 Months

A new study has found that the vaccine steadily loses its effectiveness over time.

The recent surge in COVID cases, hospitalizations, and deaths has the country on edge. Even people who are fully vaccinated are concerned, with breakthrough infections being reported and the Centers for Disease Control and Prevention (CDC) reversing their mask-free guidance for vaccinated individuals. While experts maintain that vaccination is still the best way to protect yourself from COVID—especially from severe disease—researchers are looking into whether or not the vaccines become less effective over time. In fact, Pfizer's CEO just revealed that Pfizer's efficacy starts to drop as early as two months after people get their second dose.

RELATED: 40 Percent of People Who Get Severe COVID After Pfizer Have This in Common.

During a July 29 episode of CNBC's The Exchange, Pfizer CEO Albert Bourla discussed the findings of a new company-funded study, which has not yet been peer-reviewed but was released early as a preprint on medRxiv. The researchers evaluated the vaccine's efficacy for more than 44,000 Pfizer recipients across the U.S. and in other countries over the course of six months.

According to the study, the vaccine was most protective between one week and two months after people received the second dose, with a 96.2 percent efficacy against infection. But the researchers also found that every two months, the effectiveness of the vaccine declines by about 6 percent. Between two to less than four months, Pfizer's vaccine had dropped to 90.1 percent.

Pfizer's efficacy after "four to six months was approximately 84 percent," Bourla said. Despite being slightly less protective against symptomatic infection, these results show that the vaccine is still highly effective after four months. And in terms of protection against severe disease, Pfizer's vaccine did not waver, staying at around 97 percent.

When asked if it was normal for a vaccine's efficacy to drop in such a way after just four to six months, Bourla assured that this "is not uncommon." However, he did say that the study confirms the need for a third dose, adding that research was completed before the rise of the Delta variant.

RELATED: For more up-to-date information, sign up for our daily newsletter.

"The good news is that we are very, very confident that a third dose, a booster, will take up the immune response to levels that will be enough to protect against the Delta variant," he said. According to Bourla, Pfizer plans to formally submit data to U.S. regulators about the benefits of a third COVID vaccine dose by mid-August.

However, when Pfizer first announced its plans to push booster shots so soon, U.S. regulators were not on board. On July 8, the U.S. Food and Drug Administration (FDA) and the CDC issued a joint-statement against Pfizer's push, insisting that, "Americans who have been fully vaccinated do not need a booster shot at this time."

Per the statement, the FDA, CDC, and the National Institutes of Health (NIH) are currently involved in a "science-based, rigorous process" to determine if, and when, a booster vaccine might be necessary. "This process takes into account laboratory data, clinical trial data, and cohort data—which can include data from specific pharmaceutical companies, but does not rely on those data exclusively," the agencies said.

Other health experts have not expressed concern for booster shots as of right now either, especially considering the fact that many countries have not yet received sufficient vaccine doses to supply first or second shots. "There's not enough evidence right now to support that that is somehow the best use of resources," Natalie Dean, PhD, a biostatistician at Emory University in Atlanta, told The New York Times.

RELATED: Pfizer Only Works Against the Delta Variant If You Do This, New Study Says.

Filed Under