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New data from Addenbrooke’s Hospital in Cambridge suggest that a single dose of the Pfizer BioNTech vaccine can reduce the number of asymptomatic SARS-CoV-2 infections by four times.
This implies that the vaccine could significantly reduce the risk of transmission of the virus from asymptomatic people, in addition to protecting others from getting sick.
The study by a team from Cambridge University Hospitals NHS Foundation Trust (CUH) and the University of Cambridge analyzed the results of thousands of COVID-19 tests performed each week as part of their screening programs on hospital staff that did not show signs of infection
Vaccination for healthcare workers at the CUH site began on December 8, 2020, with mass vaccination beginning on January 8, 2021. During a two-week period between January 18 and January 31, 2021, the team screened a similar number of vaccinated and unvaccinated personnel using around 4,400 PCR. tests per week.
The results were then separated to identify unvaccinated staff and staff who had been vaccinated more than 12 days prior to testing (when protection against symptomatic infection is believed to exist).
The study, which has not yet been peer-reviewed, found that 26 of 3,252 (0 · 80%) tests from unvaccinated healthcare workers were positive.
This compared to 13 out of 3,535 (0.37%) health worker tests less than 12 days after vaccination and 4 out of 1,989 (0 · 20%) health worker tests at 12 days or more after vaccination. vaccination.
This suggests a four-fold decrease in the risk of asymptomatic COVID-19 infection among healthcare workers who have been vaccinated for more than 12 days (75 percent protection). The level of asymptomatic infection was also halved in those vaccinated for less than 12 days.
Dr Mike Weekes, an infectious disease specialist at CUH and the University of Cambridge Department of Medicine, who led the study, said: “This is great news: the Pfizer vaccine doesn’t just protect against the disease SARS. -CoV-2, but also helps prevent infection, reducing the possibility of the virus spreading to other people.
“This will be good news when we start to draw a roadmap to get out of the confinement, but we must remember that the vaccine does not provide complete protection for everyone. We still need social distancing, masks, hand hygiene and regular tests until the pandemic is much better controlled. “
Our findings show a dramatic reduction in the rate of positive screenings among asymptomatic healthcare workers after a single dose of the Pfizer-BioNTech vaccine. This is fantastic news for hospital staff and patients alike, who can rest assured that the current mass vaccination strategy protects against asymptomatic virus transport as well as symptomatic disease, making hospitals still places. safer “.
Dr. Nick Jones, first study author and microbiology / infectious disease registrar, Cambridge University Hospitals
Giles Wright, director of programs for the CUH Vaccination Center, said: “Throughout the pandemic thus far, we have taken a systematic approach to keeping our staff safe and sound. The tremendous efforts of everyone involved in the testing programs, Screening and vaccination at CUH is making the plan a reality. We are very encouraged by the results of our research. It gives us more hope for the near future. “
When the team included symptomatic healthcare workers, their analyzes showed similar reductions. 56 out of 3,282 (1 · 71%) unvaccinated healthcare workers tested positive. This compared with 8 out of 1,997 (0 · 40%) healthcare workers at 12 or more days after vaccination, a reduction of 4 · 3 times.
Researchers have published their data before peer review due to the urgent need to share information related to the pandemic.
Source:
Magazine reference:
The single dose BNT162b2 vaccine protects against asymptomatic SARS-CoV-2 infection. Autorea. doi.org/10.22541/au.161420511.12987747/v1.
