Search

Single dose of Pfizer BioNTech vaccine reduces asymptomatic infections and potential for SARS-CoV-2 transmission - Medical Xpress

Single dose of Pfizer BioNTech vaccine reduces asymptomatic infections and potential for SARS-CoV-2 transmission
Figure : Proportion of HCWs testing positive for SARS-CoV-2 in the CUHNHFT asymptomatic screening programme (grey bars; week 1, 18/01/2021-24/01/2021; week 2, 25/01/2021-31/01/2021) and Ct values of positive tests (CT36; blue dots; both weeks). RT-PCR targeting the SARS-CoV-2 ORF1ab genes was conducted at the Cambridge COVID-19 Testing Centre (part of the UK Lighthouse Labs Network). For proportions testing positive, p values for pair-wise comparisons of unvaccinated HCWs with HCWs 12 days or> 12 days post-vaccination are shown (Fisher’s exact test; both weeks). For Ct values, medians ± interquartile ranges are shown. Credit: DOI: 10.22541/au.161420511.12987747/v1

New data from Addenbrooke's Hospital in Cambridge suggests that a single dose of the Pfizer BioNTech vaccine can reduce by four-fold the number of asymptomatic SARS-CoV-2 infections. This implies that the vaccine could significantly reduce the risk of transmission of the virus from people who are asymptomatic, as well as protecting others from getting ill.

The study by a team at Cambridge University Hospitals NHS Foundation Trust (CUH) and the University of Cambridge analyzed results from thousands of COVID-19 tests carried out each week as part its screening programs on hospital staff who showed no signs of infection.

Vaccination for on the CUH site began on 8 December 2020, with mass vaccination from 8 January 2021. During a two-week period between 18 and 31 January 2021, the team screened similar numbers of vaccinated and unvaccinated staff using around 4,400 PCR tests per week.

The results were then separated out to identify unvaccinated staff, and staff who had been vaccinated more than 12 days prior to testing (when protection against symptomatic infection is thought to occur).

The study, which is yet to be peer-reviewed, found that 26 out of 3,252 (0·80%) tests from unvaccinated were positive. This compared to 13 out of 3,535 (0.37%) tests from workers less than 12 days post-vaccination and four out of 1,989 (0·20%) tests from healthcare workers at 12 days or more post-vaccination.

This suggests a four-fold decrease in the risk of asymptomatic COVID-19 infection amongst 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's Department of Medicine, who led the study, said: "This is great news—the Pfizer vaccine not only provides protection against becoming ill from SARS-CoV-2 but also helps prevent infection, reducing the potential for the virus to be passed on to others.

"This will be welcome news as we begin to plot a roadmap out of the lockdown, but we have to remember that the vaccine doesn't give complete protection for everyone. We still need social distancing, masks, hand hygiene and regular testing until the pandemic is under much better control."

Dr. Nick Jones, first author on the study and an /microbiology registrar at CUH, said: "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. This is fantastic news for both and patients, who can be reassured that the current mass vaccination strategy is protecting against asymptomatic carriage of the virus in addition to symptomatic disease, thereby making hospitals even safer places to be."

Giles Wright, program director for the CUH Vaccination Hub said: "Throughout the pandemic so far, we have taken a systematic approach to keeping our staff safe and well. The huge efforts of all those involved in the testing, tracing and vaccination programs at CUH are making the plan a reality. We are very encouraged by the findings of our research. It gives further hope for the near future."

When the team included symptomatic healthcare workers, their analyses showed similar reductions. 56 out of 3,282 (1·71%) unvaccinated healthcare workers tested positive. This compared to eight out of 1,997 (0·40%) healthcare workers at 12 or more days post-vaccination, a 4·3-fold reduction.


Explore further

Pfizer/BioNTech first dose 85% effective after 2-4 weeks: study

More information: Jones, NK et al. Single-dose BNT162b2 vaccine protects against asymptomatic SARS-CoV-2 infection. 24 Feb 2020; DOI: 10.22541/au.161420511.12987747/v1

Citation: Single dose of Pfizer BioNTech vaccine reduces asymptomatic infections and potential for SARS-CoV-2 transmission (2021, February 26) retrieved 26 February 2021 from https://medicalxpress.com/news/2021-02-dose-pfizer-biontech-vaccine-asymptomatic.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Let's block ads! (Why?)


https://news.google.com/__i/rss/rd/articles/CBMiVWh0dHBzOi8vbWVkaWNhbHhwcmVzcy5jb20vbmV3cy8yMDIxLTAyLWRvc2UtcGZpemVyLWJpb250ZWNoLXZhY2NpbmUtYXN5bXB0b21hdGljLmh0bWzSAVRodHRwczovL21lZGljYWx4cHJlc3MuY29tL25ld3MvMjAyMS0wMi1kb3NlLXBmaXplci1iaW9udGVjaC12YWNjaW5lLWFzeW1wdG9tYXRpYy5hbXA?oc=5

2021-02-26 14:31:15Z
52781406314758

Bagikan Berita Ini

0 Response to "Single dose of Pfizer BioNTech vaccine reduces asymptomatic infections and potential for SARS-CoV-2 transmission - Medical Xpress"

Post a Comment

Powered by Blogger.