We already know that approved vaccines are highly effective protecting you against Covid-19, especially for serious cases. We now have great data showing they protect others from you as well. In other words – if you’re vaccinated you aren’t just preventing yourself from getting sick, you’re preventing yourself from being a carrier of the virus too.
There has been debate over whether vaccinated people can still get asymptomatic infections and transmit the virus to others. The study, by researchers at the Centers for Disease Control and Prevention, suggested that transmission may be extremely unlikely, as infections were so rare.
There also has been concern that variants may render the vaccines less effective. The study’s results do not confirm that fear.
The CDC studied vaccinated health care personnel, first responders and other essential workers between December and March. Study participants had received either the Pfizer-BioNTech or Moderna vaccines. They found,
- 80% effectiveness against infection two weeks after the first shot but before the second
- 90% effectiveness against infection two weeks after the second shot.
Someone vaccinated with two shots of an mRNA vaccine highly unlikely to have even an asymptomatic case of Covid-19, meaning they aren’t likely to have it and spread it without feeling sick. In other words these vaccines are nearly as effective against asymptomatic disease as they were found to be effective against symptoms in Phase 3 trial data.
Some have suggested that trial data may overstate the effectiveness of the vaccines, because those trials occurred before current variants of the virus had become widespread. However this study, testing participants for Covid-19 weekly, occurred during spread of current variants.
Your risk isn’t zero but we do things that entail some risk all the time, like driving in a car. With a 90% reduction in risk, the science supports a judgment to travel if that’s something you value.