"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.

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).

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.