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Does the Pfizer vaccine work against the COVID variants?

Three Pfizer vaccine vials in front of Pfizer logo - vaccine work against COVID variants?
Photo via Marco Verch Professional Photographer/Flickr (CC BY 2.0)
  • This story is regularly updated for relevance. Last updated; May 5, 2021

The U.K. and South African COVID-19 variants continue to spread worldwide, sparking concerns about whether the vaccines that millions of people have already received will be effective after all. The Pfizer vaccine is one of the most available options, pushing many experts to explore a pressing question: does the Pfizer vaccine work against the variants?

According to a non-peer reviewed study published in early February, the answer is yes. The Pfizer vaccine works fairly effectively at fighting the new variants of COVID-19. 

The study found that the Pfizer vaccine’s first dose did not produce enough antibodies to neutralize the variants, but it did make enough T cells to fight them effectively. Helper T cells, a type of white blood cell, play a crucial role in fighting COVID-19, according to Medical News Today.

That means the Pfizer vaccine may not make your body immune to COVID-19 variants, but it will help your body fight and lead to fewer, milder cases. Following a vaccination, you will be more likely to experience mild flu-like symptoms rather than requiring hospitalization. 

William James, one of the study’s authors and a professor of virology at the University of Oxford, told the Guardian this may explain why patients experience stronger side effects after the second dose. 

“It may not necessarily protect you against infection, but it’s very likely that this first dose will make it much easier for your immune system to make a good response the next time around,” James said. “We think this is why that second dose produces such a good strong antibody response, because the T cells are already there, ready to react.”

The study also found that people receive a boost in antibodies from the second dose of the Pfizer vaccine, making it more critical than ever to get both doses. 

“In more than 90% of cases, the antibodies that people are generating after the second dose are up at the sort of level that neutralizes the virus and which we would expect to protect them from infection,” James told the Guardian. “We’re pretty confident that they’ll be protected from infection by the South African strain and the Kent strain, as well as the [original] strain of the virus.” 

Despite his study only incorporating the Pfizer vaccine, James said he suspects its findings apply to the other vaccines. That backs up a January statement from Moderna claiming the vaccine effectively fought the variants. 

In April 2021, two more independent studies showed Pfizer was effective against multiple variants. “The take-home message is that the vaccines are going to work against the New York variant and the South African variant and the U.K. variant,” Nathan Landau, a virologist at N.Y.U.’s Grossman School of Medicine, told the New York Times.

Dr. Ugur Sahin, who co-founded BioNTech, had more good news in May 2021. “So far, the data is really encouraging for all types of variants,” he said, via the CBC. “We do not have any evidence that our vaccine would not work against any of the prevalent variants.”

Experts still believe the AstraZeneca vaccine is not effective enough at fighting the South African variant of the virus. After experts discovered the vaccine did not have a high enough efficacy against the South African variant, they halted its distribution in the region.  

On March 30, it was reported that the Moderna and Pfizer versions were “robustly effective in preventing infections in real-life conditions,” according to the Washington Post. In a study of 4,000 essential workers, researchers discovered that both vaccines reduced the risk of infection by 90% after people were fully vaccinated (and 80% after just one dose).

The Pfizer news comes as a particular relief for the United States, where scientists predicted the U.K. strain would become the predominant variant by March 2021 and where that B.1.1.7 strain was reportedly putting more young adults in the hospital than before.

In March, studies showed that the Pfizer vaccine also was effective against the variant that was first discovered in Brazil. Another study out of Israel in March showed that the Pfizer vaccine was 94% effective against asymptomatic COVID cases and 97% effective against symptomatic cases.

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Sources: Research Square, Medical News Today, Guardian, U.S. News 


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