Even if you are fully vaccinated, chances are that you can still catch COVID and pass on the deadly disease to people at home, according to a study published in the journal The Lancet Infectious Diseases on Friday, 29 October.

Households are the site of most SARS-CoV-2 transmission globally. The study, which focused on densely sampled household contacts exposed to the delta variant, found that even with no or few symptoms, the chance of transmitting the virus to other unvaccinated housemates is about two in five, or 38 percent.

This drops to one in four, or 25 percent, if housemates are also fully vaccinated.

Various studies have also shown the waning protection of these vaccines, effectively pressing the need for boosters.

The study included 440 households in London and Bolton doing PCR COVID tests between September 2020 and September 2021.

The results reveal that even after two doses of COVID vaccines people can appear to be just as infectious. In other words, although vaccinated people can clear the infection more quickly, their peak viral load – when people are most infectious – remains similar to that seen in unvaccinated people, meaning they can still readily pass on the virus in household settings.

"Vaccination reduces the risk of delta variant infection and accelerates viral clearance. Nonetheless, fully vaccinated individuals with breakthrough infections have peak viral load similar to unvaccinated cases and can efficiently transmit infection in household settings, including to fully vaccinated contacts. Host-virus interactions early in infection may shape the entire viral trajectory," Lalvani said.

Continued public health and social measures to curb transmission – such as mask wearing, social distancing, and testing – thus remain important, even in vaccinated individuals, the study suggested.

(This story was published from a syndicated feed. Only the headline and picture has been edited by FIT.)