Vaccinated people easily transmit Delta variant in households, UK study finds

Last week, a British study found that the Delta variant of the coronavirus can easily transmit from vaccinated people to others in their household. The study also found, though, that those household contacts were less likely to get infected if they were also vaccinated.

The study conducted by the Imperial College London shows how the Delta variant, which is highly transmissible, can spread in a vaccinated population. Despite this finding, the researchers emphasized the argument for vaccination citing its ability to lower the risk of serious illness from COVID-19 infection. They also found in their study that while infections in vaccinated people cleared faster than in unvaccinated, the peak viral load was similar between the two groups.

Dr. Anika Singanayagam, a lead author of the study, said, “By carrying out repeated and frequent sampling from contacts of COVID-19 cases, we found that vaccinated people can contract and pass on infection within households, including to vaccinated household members.” She continued, “Our findings provide important insights into… why the Delta variant is continuing to cause high COVID-19 case numbers around the world, even in countries with high vaccination rates.”

The case studied 621 participants found that out of 205 household contacts of those with Delta COVID-19 infection, 38 percent of unvaccinated household contacts went on to test positive, whereas 25 percent of vaccinated contacts went on to test positive. 

The study indicated that those vaccinated contacts who eventually tested positive had generally received their vaccine earlier than those who tested negative. Authors of the study said this finding was evidence of disappearing immunity, supporting the necessity of booster shots.

Neil Ferguson, Imperial epidemiologist, seems to think it will be unlikely that Britain would reach “herd immunity” for long due to the transmissibility of the Delta variant. “That may happen in the next few weeks: if the epidemic’s current transmission peaks and then starts declining, we have by definition in some sense reached herd immunity, but it is not going to be a permanent thing,” he commented to reporters. “Immunity wanes over time, it is imperfect, so you still get transmission happening, and that is why the booster programme is so important.” 




Leave a Reply