Pfizer Vaccine Is Effective Against the Two Worst Variants, Study Says

Two real-world use studies found that it prevents severe outcomes, including death.

Months after it began, the COVID-19 vaccine rollout in the U.S. is showing signs that the highly effective immunizations that are being used are helping to bring down the national infection rate. But highly contagious variants of the virus that emerged around the time of the Moderna and Pfizer-BioNTech vaccines release have continued to concern some health officials that they may be able to elude the shots' efficacy. Fortunately, a pair of new studies have found that the Pfizer vaccine is still highly effective at protecting against two of the worst variants currently circulating. Read on to see what researchers found, and for more on how well other shots work, This Is How Much the Moderna Vaccine Really Protects You, New Study Says.

The Pfizer vaccine is incredibly effective against the U.K. and South African variants.


According to two separate real-world studies conducted in Israel and Qatar, the Pfizer COVID-19 vaccine is highly effective against two of the most concerning variants: B.1.1.7, which was first detected in the U.K., and B.1.351, which originated in South Africa. The findings come as scientists and pharmaceutical companies attempt to gauge how well existing vaccines work against the highly contagious strains.

"This is really good news," Annelies Wilder-Smith, MD, an infectious disease researcher at the London School of Hygiene and Tropical Medicine, told The New York Times. "At this point in time, we can confidently say that we can use this vaccine, even in the presence of circulating variants of concern."

A study from Qatar found the Pfizer vaccine to be up to 90 percent effective against variants.

Pfizer vaccine

The first study, which was published in a letter to the New England Journal of Medicine, analyzed data from Qatar's COVID-19 database that included information on more than 200,000 people over February and March. The study authors wrote that at this time, the B.1.1.7 and B.1.351 variants were the "predominant" strains in the country.

Results showed that Pfizer's vaccine was 87 to 89.5 percent effective at preventing infection with B.1.1.7 two weeks after their second dose had been administered. The researchers also saw promising results regarding B.1.351, finding that the vaccine was 72.1 to 75 percent effective at preventing infection two weeks after the second dose, The Times reports. And for more on the latest immunization research, Pfizer's Vaccine Protects You for at Least This Long, Study Finds.

A study from Israel found the Pfizer vaccine was effective at preventing severe outcomes with B.1.1.7.

Pfizer-BioNTech COVID-19 Vaccine closeup
cortex-film / Shutterstock

The second set of new research, which was originally published in the medical journal The Lancet, comes from a joint study conducted by Israel's Ministry of Health and Pfizer. The team analyzed over 230,000 COVID-19 cases that were reported in the country from Jan. 24 to Apr. 3 to find that the B.1.1.7 "U.K. variant" was responsible for about 95 percent of all cases there at the time. About 50 percent of the country's population was also vaccinated during this period, The Times reports.

The study found that the Pfizer vaccine was 96.5 percent effective at protecting against infection, 98 percent against hospitalization, and 98.1 percent against death 14 days after the second dose, and even maintained a 94 percent efficacy for those 85 years old and up. However, the authors pointed out that those with only one dose saw far less protection, finding that a single shot provided 57.7 percent protection against infection, 75.7 percent against hospitalization, and 77 percent against death.

Both studies show the importance of getting the two doses required for full vaccination.

Covid-19 vaccination record card with syringe and vial

While both studies provided plenty of reassurance of the vaccine's high efficacy, one expert pointed out that it also highlights the importance of receiving both shots to be fully protected. Data from the Centers for Disease Control and Prevention (CDC) has recently shown that millions of people have missed or not returned for their follow-up injections.

"It really strongly emphasizes, with the variants, that need for the second dose," Kathleen Neuzil, MD, director of the Center for Vaccine Development at the University of Maryland School of Medicine, told The Washington Post. "Which is a message we've been delivering, but now we have human clinical data to support that message." And for more on potential boosters, This Is When You'll Need a Third COVID Shot, BioNTech CEO Says.

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Zachary Mack
Zach is a freelance writer specializing in beer, wine, food, spirits, and travel. He is based in Manhattan. Read more
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