As the Delta variant dominates countries across the globe, we're learning more and more about how this iteration of COVID is unlike any we've seen before. According to recent research, Delta is not only nearly twice as contagious as previous variants, but it may also cause more severe illness in those infected. Thankfully, there are ways to protect yourself from this highly infectious and now dominant variant—including one method based on new research that's been found to be up to 60 percent effective.
Researchers from Imperial College London just released the latest findings from their ongoing Real-Time Assessment of Community Transmission (REACT) trial. The new study, which was released as a preprint on Aug. 4, looked at COVID cases during a period in which the Delta variant had completely taken over infections, replacing the previously dominant Alpha variant. The researchers had more than 98,000 people test themselves for the virus at home, and then analyzed their samples through PCR testing.
According to the study, the participants who had received both doses of a COVID vaccine were around 50 to 60 percent less likely to get infected with the Delta variant compared to unvaccinated people. For both symptomatic and asymptomatic infections, double vaccination resulted in a 50 percent lower chance of testing positive with the variant. But when looking at symptomatic infections only, double vaccinated people were around 59 percent less likely to get sick from the Delta variant.
"These findings confirm our previous data showing that both doses of a vaccine offer good protection against getting infected. However we can also see that there is still a risk of infection, as no vaccine is 100 percent effective, and we know that some double vaccinated people can still become ill from the virus," Paul Elliott, PhD, director of the REACT trial and professor at the Imperial's School of Public Health, said in a statement.
The researchers for this study also found that double vaccinated people were less likely to test positive after being exposed to the virus compared to unvaccinated people. Furthermore, vaccinated people may also be less likely than unvaccinated people to spread the virus to others—even amid the Delta variant.
"Today's results are a stark reminder of the importance of getting vaccinated against COVID-19, with those unvaccinated three times more likely to test positive in this round than those who are fully vaccinated," Kelly Beaver, the managing director for public affairs at Ipsos MORI, a market research company that has partnered with Imperial for the trial, said in a statement. "This is underscored by the indications in this report that fully vaccinated people are less likely to transmit the virus to others, an important development in understanding how we can beat the virus."
The incidence of transmission among vaccinated people has been a recent concern for the U.S. Centers for Disease Control and Prevention (CDC), prompting their recent mask guidance reversal, which has asked vaccinated people in certain areas to wear masks indoors.
According to a July 30 report from the CDC, data from an outbreak in Barnstable County, Massachusetts showed that the Delta variant produced similarly high viral loads in both unvaccinated and vaccinated people. "High viral loads suggest an increased risk of transmission and raised concern that, unlike with other variants, vaccinated people infected with Delta can transmit the virus," the agency said.