ABOVE: © ISTOCK, ALEXANDROS MICHAILIDIS
People who became infected with SARS-CoV-2 after receiving one dose of Pfizer’s COVID-19 vaccine harbored about four times less virus than did unvaccinated people who caught the virus, according to preliminary results posted to the preprint server medRxiv on February 8.
Several COVID-19 vaccines, including Pfizer’s version, are about 95 percent effective in preventing disease. But there’s less known about whether vaccinated individuals can still transmit the SARS-CoV-2 virus to others.
In the study, which has not yet undergone peer review, researchers in Israel measured the viral loads in 2,897 unvaccinated people and in 2,897 age- and sex-matched people who had received their first of two doses of the Pfizer vaccine. The authors conclude in their report that “viral load is reduced 4-fold for infections occurring 12–28 days after the first dose of vaccine. These reduced viral loads hint to lower infectiousness, further contributing to ...
