After just 1 dose of the Pfizer vaccine, the COVID transmission rate drops dramatically

pfizer covid transmission one vaccine dose efficacy
Photo via Marco Verch/Flickr (CC BY 2.0)

Despite Pfizer’s recommendation for a two-dose process in using its COVID-19 vaccine, encouraging study results are showing protections coming from just a single dose of the vaccine, including a drop in coronavirus transmission rates. 

Reuters reported that a single dose of the Pfizer/BioNtech COVID-19 vaccine, approved for use in the U.S. in December 2020, reduces the number of asymptomatic infections and could significantly reduce the risk of transmission of the virus. 

According to Reuters, researchers analyzed results from thousands of COVID-19 tests carried out each week as part of hospital screenings of healthcare staff in Cambridge, England.

“Our findings show a dramatic reduction in the rate of positive screening tests among asymptomatic healthcare workers after a single dose of the Pfizer/BioNTech vaccine,” reported Nick Jones, an infectious diseases specialist at Cambridge University Hospital who co-led the study.

While 0.8% of unvaccinated workers tested positive, only 0.37% of those less than 12 days post-vaccination and 0.2% of workers 12 days or more post-vaccination tested positive. 

Further evidence of the Pfizer vaccine’s overall efficacy came from the results of two studies published in The Lancet, via the New York Times, noting that for people who have already tested positive for COVID-19, a single dose of that vaccine is “enough to provide robust protection from the coronavirus.” 

Those studies, also originating in the U.K., were “among the first fully vetted papers to weigh in on how to vaccinate people who have had COVID-19, added strong evidence to the case for giving just one dose of the Pfizer vaccine to people who already have antibodies against the virus.” 

The report concluded that not only could those findings “potentially accelerate vaccine rollout,” but could also provide “wider coverage without compromising vaccine-induced immunity.” That could, in turn, “help reduce variant emergence,” which has been a concern for researchers worldwide in recent weeks. 

As the Times article noted, “Some researchers in the United States are trying to persuade the Centers for Disease Control and Prevention to recommend giving only one dose to people who have recovered from COVID-19. The studies from Britain seem likely to put pressure on health officials there to consider the same approach.” 

And yet, there is already research underway to see what the benefits of a third dose of the Pfizer vaccine could do. NBC News noted that the company is conducting trials with a booster dose for people who received their first doses of the vaccine more than six months ago. 

Pfizer CEO Albert Bourla told NBC News that the hope is for a third dose of the vaccine boosting the immune response even higher. That would conceivably offer more protection against variants.

“We believe that the third dose will raise the antibody response 10- to 20- fold,” Bourla said. 

That article noted, “As SARS-CoV-2 changes, the vaccines may have to be tweaked,” adding that the Food and Drug Administration issued a Feb. 22 statement noting that “vaccine manufacturers may be able to ease away from lengthy clinical trials to prove safety and effectiveness for vaccines that have been tweaked to account for variants.” 

Those changes would be similar to the influenza vaccine’s changing annual composition, accounting for which strains are determined most likely to infect people.

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Sources: Reuters, New York Times, NBC News, The Lancet

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