Pfizer COVID-19 Vaccine Protects For At Least Six Months

The company also says its vaccine is effective against the worrisome South African variant.

woman getting vaccinated

Medically reviewed in April 2021

Updated on April 1, 2021

Pfizer’s COVID-19 vaccine safely protects against the disease for at least six months after the second dose, according to its ongoing late-stage trial.

The company also says its vaccine, which was developed in partnership with the German biotech company BioNTech, is effective against the worrisome South African coronavirus variant. Experts have warned this mutant strain of the virus could possibly evade available vaccines.

“The high vaccine efficacy observed through up to six months following a second dose and against the variant prevalent in South Africa provides further confidence in our vaccine’s overall effectiveness,” said Pfizer Chairman and CEO, Albert Bourla, in an April 1 news release.

“It is an important step to further confirm the strong efficacy and good safety data we have seen so far, especially in a longer-term follow-up,” added Ugur Sahin, CEO and co-founder of BioNTech.

“These data also provide the first clinical results that a vaccine can effectively protect against currently circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population,” Sahin noted.

What the trial results show
Overall, more than 44,000 people age 16 and older are involved in Pfizer’s late-stage trial that is tracking the vaccine’s safety. The FDA requires all companies investigating COVID-19 vaccines to review safety and efficacy at key milestones.

Out of 927 confirmed symptomatic cases of COVID-19 in the trial, 77 people received the vaccine, and 850 people were in the placebo group and not vaccinated. This shows the Pfizer vaccine was 91.3 percent effective against COVID-19 up to six months after the second dose.

The vaccine was 100 percent effective against severe COVID-19 as defined by the Centers for Disease Control and Prevention (CDC) and 95.3 percent effective against severe disease as defined by the U.S. Food and Drug Administration (FDA).

Safety data from the Phase 3 trial, which includes follow-up data on more than 12,000 vaccinated people collected at least six months since their second dose, also found the vaccine was well-tolerated.

“These data confirm the favorable efficacy and safety profile of our vaccine and position us to submit a Biologics License Application to the U.S. FDA,” Bourla said.

Pfizer and BioNTech released topline results, which summarized their key findings. Pfizer says it plans to submit detailed findings to a peer-reviewed scientific journal for publication.

Why this update is important
The ideal situation, a much-discussed outcome since the pandemic began, is herd immunity.

Herd immunity is achieved once enough people survive infection and/or get vaccinated, making the spread of the disease unlikely—at least for a certain period of time, depending on how long immunity lasts.

Exactly what percentage of a population needs to be COVID-immune to achieve herd immunity is still unclear. The number depends on many factors that are still hard to pin down, including the efficacy of the vaccine among unmasked people and how long protection lasts.

As more data is collected on the vaccine rolling out across the United States, the closer we get to being able to answer some of these questions.

Article sources open article sources

Pfizer. “PFIZER AND BIONTECH CONFIRM HIGH EFFICACY AND NO SERIOUS SAFETY CONCERNS THROUGH UP TO SIX MONTHS FOLLOWING SECOND DOSE IN UPDATED TOPLINE ANALYSIS OF LANDMARK COVID-19 VACCINE STUDY.” Apr 1, 2021.
World Health Organization. “Coronavirus disease (COVID-19): Herd immunity, lockdowns and COVID-19.” Dec 31, 2020.

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