Pfizer's Working On a Third Dose of the COVID-19 Vaccine That 'Strongly' Boosts Protection

While more research is needed, the pharmaceutical giant recently announced "encouraging" findings that suggest a third dose of its vaccine can help protect against the highly contagious Delta variant.

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Earlier this summer, it felt like the COVID-19 pandemic had turned a corner. Fully vaccinated people were told by the Centers for Disease Control and Prevention in May that they no longer needed to wear masks in most settings, and the number of COVID-19 cases in the U.S. had also declined for a time being. But then, the Delta (B.1.617.2) variant really started to rear its ugly head.

The Delta variant is responsible for around 82 percent of new COVID-19 cases in the U.S. as of July 17, according to data from the CDC. It's also been linked to an 85 percent higher risk of hospitalization than other strands, and is 60 percent more transmissible than the Alpha (B.1.17) variant, the previously dominant strain, according to a June 2021 study. (

Recent studies from England and Scotland suggest that the Pfizer vaccine is not as effective at protecting against the Delta variant as it is for the Alpha, according to the CDC. Now, that doesn't mean the vaccine can't help you steer clear of symptomatic disease from the strain — it just means that it's not as effective at doing so compared to its ability to fight against the Alpha. But some potentially good news: On Wednesday, Pfizer announced that a third dose of its COVID-19 vaccine can increase protection against the Delta variant, beyond that from its current two doses. (

The data posted online from Pfizer suggests that the third dose of the vaccine can provide more than five times the antibody levels against the Delta variant in people between 18 and 55 compared to that from the standard two shots. And, according to the company's findings, the booster was even more effective in people 65 to 85 years old, increasing antibody levels nearly 11-fold among this cohort. All that being said, the data set was small — just 23 people were involved — and the findings have yet to be peer-reviewed or published in a medical journal yet.

"We continue to believe it is likely that a third dose booster may be needed within six to 12 months after full vaccination to maintain the highest levels of protection, and studies are underway to evaluate the safety and immunogenicity of a third dose," said Mikael Dolsten, M.D., Ph.D., chief scientific officer and president of Worldwide Research, Development, and Medicalfor Pfizer, in a statement Wednesday. Dr. Dolsten went on to add, "These preliminary data are very encouraging as Delta continues to spread."

Apparently, the protection afforded by the standard two-dose Pfizer vaccine may begin "to wane" six months after inoculation, according to the pharmaceutical giant's presentation on Wednesday. So, a potential third dose could be particularly helpful in, quite simply, upholding peoples' protection against COVID-19 overall. It's important to note, however, that antibody levels — although an important aspect of immunity — are not the only metric for measuring a person's ability to fight the virus, according to The New York Times. In other words, more time and research are needed to truly understand whether Pfizer's third dose is, err, all it's cracked up to be.

In addition to Pfizer, other vaccine makers have also backed the idea of a booster shot. Moderna co-founder Derrick Rossi told CTV News in early July that a regular booster shot of the COVID-19 vaccine will "almost certainly" be needed to maintain immunity against the virus. Rossie even went as far as to say, "It might not be surprising that we need a booster shot every year." (

Johnson & Johnson CEO Alex Gorsky also jumped on the boosters-in-the-future train during The Wall Street Journal's Tech Health conference in early June, saying that the added dose(s) are likely to be needed for his company's vaccine — at least until herd immunity (aka when the majority of a population is immune to an infectious disease) is achieved. "We could be looking at this tagging along with the flu shot, likely over the next several years," he added.

But in early July, the CDC and Food and Drug Administration released a joint statement saying that "Americans who have been fully vaccinated do not need a booster shot at this time" and that the "FDA, CDC, and NIH [National Institutes of Health] are engaged in a science-based, rigorous process to consider whether or when a booster might be necessary."

"We continue to review any new data as it becomes available and will keep the public informed," reads the statement "We are prepared for booster doses if and when the science demonstrates that they are needed."

In fact, on Wednesday Dr. Dolsten said that Pfizer is in "ongoing discussions" with regulatory agencies in the U.S. about a potential third booster dose of the current vaccine. If agencies decide it's necessary, Pfizer plans to submit an emergency use authorization application in August, according to Dr. Dolstein. Basically, you could be getting a COVID-19 booster shot in the next year.

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.

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