One dose of Pfizer vaccine offers significant protection for those who have had COVID-19: studies

Two new British studies published late Thursday found that a single dose of the Pfizer-BioNTech coronavirus vaccine may offer significant protection for people who have already been infected with COVID-19. 

The studies, published in the weekly peer-reviewed medical journal The Lancet, provide further evidence for increased calls among experts to give only one dose to individuals that are already carrying antibodies against the virus.

“This could potentially accelerate vaccine rollout,” researchers at University College London and Public Health England said in one of the studies. “With increasing variants (UK, South Africa, Brazil), wider coverage without compromising vaccine-induced immunity could help reduce variant emergence.” 

The Pfizer-BioNTech and Moderna vaccines, the two inoculations currently approved for emergency use by the U.S. Food and Drug Administration (FDA), require two doses administered weeks apart. The Johnson & Johnson vaccine, which an FDA panel this week found was safe and effective, only requires one dose. 

The University College and Public Health England researchers analyzed data among 51 health workers in London who have agreed to routine antibody and infection tests since March. 

The researchers found that among roughly half of the workers who had been infected, a single dose of the Pfizer-BioNTech vaccine increased their antibody levels “more than 140-fold from peak pre-vaccine levels.” 

In the second study, researchers at Imperial College London measured antibody responses among 72 health workers vaccinated in late December. 

A third of the workers showed signs of being previously infected, and among those people, one vaccine dose had “very strong” antibody responses and “very strong T-cell responses.” 

The studies provide some of the strongest evidence in favor of administering a single dose of the coronavirus vaccine for the approximately 28.4 million people who have been infected in the U.S., with a total of more than 113 million cases globally, according to data compiled by Johns Hopkins University. 

A study published by The Lancet last week that measured the Pfizer vaccine among health care workers at Sheba Medical Center in Israel found that the inoculation was 85 percent effective in preventing symptomatic cases of COVID-19 after just one dose. 

However, Anthony Fauci, the top infectious disease expert in the U.S., responded to the Israel study by saying he still believed the U.S. should stick to the approved two doses.