Pfizer, Moderna vax reduce infection risk by 91%

Washington Taking two doses of the Pfizer-BioNTech and Moderna's mRNA-based vaccines, authorised by the Food and Drug Administration, can reduce the risk of Coronavirus infection by 91 per cent, according to a new study by the US Centers for Disease Control and Prevention (CDC). Even a single dose of the mRNA vaccines can reduce the risk of infection by 81 per cent. These estimates included symptomatic and asymptomatic infections.

"Covid-19 vaccines are a critical tool in overcoming this pandemic," said CDC Director Rochelle P Walensky. "Findings from the extended timeframe of this study add to accumulating evidence that mRNA Covid-19 vaccines are effective and should prevent most infections but that fully vaccinated people who still get Covid-19 are likely to have milder, shorter illness and appear to be less likely to spread the virus to others. These benefits are another important reason to get vaccinated," Walensky added.

The study also showed that mRNA vaccination benefits people who get Covid-19 despite being fully vaccinated (14 or more days after dose 2) or partially vaccinated (14 or more days after dose 1 to 13 days after dose 2). Fully or partially vaccinated people who developed Covid-19 spent on average six fewer total days sick and two fewer days sick in bed. They also had about a 60 per cent lower risk of developing symptoms, like fever or chills, compared to those who were unvaccinated. Some study participants infected with SARS-CoV-2 did not develop symptoms.

People who were fully or partially vaccinated and then got Covid-19 had 40 per cent less detectable virus in their nose (that is, a lower viral load), and the virus was detected for six fewer days (that is, viral shedding) compared to those who were unvaccinated when infected.