People who become infected with the novel coronavirus post-vaccination are likely to be protected against severe illness, and a new study suggests they also may be less contagious. At a large Israeli health maintenance organization where 650,000 members received the two-dose vaccine from Pfizer Inc and BioNTech, researchers identified 2,897 patients who later tested positive for COVID-19. The amounts of virus on swab samples from the nose and throat were reduced four-fold for infections occurring at least 12 days after the first dose of vaccine compared to what is typically seen in unvaccinated COVID-19 patients, the research team from Maccabi Health Services and the Technion - Israel Institute of Technology found. Viral loads are known to be linked with contagiousness and disease severity. But this study was not a randomized trial and it did not look at patients' viral loads over time, nor the rates at which their contacts became infected, which would be the most direct evidence of whether a vaccine reduces virus transmission. Still, the authors concluded in a paper posted on Monday on the medical website medRxiv ahead of peer review, "These reduced viral loads hint to lower infectiousness, further contributing to vaccine impact on virus spread." The authors declined to comment on the study until a peer-reviewed version of the report is available. —Reuters Staff Source
