Are you completely vaccinated? COVID-19 can still be spread at home

According to a study published in the journal The Lancet Infectious Diseases, even if you are fully vaccinated, you can catch COVID-19 and spread the deadly disease to others at home.

The majority of SARS-CoV-2 transmission occurs in households around the world. The study, which focused on densely sampled household contacts exposed to the delta variant, discovered that even with no or few symptoms, the likelihood of transmitting the virus to other unvaccinated housemates is about two in five, or 38%.

If housemates are also fully vaccinated, this drops to one in four, or 25%.

While COVID vaccines do prevent serious COVID illness and deaths, they are less effective at preventing spread of infections, particularly since the emergence of the more infectious Delta variant.

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

“This finding indicates that breakthrough infections in fully vaccinated people can efficiently transmit infection in the household setting,” said corresponding author Prof Ajit Lalvani, National Heart and Lung Institute, Imperial College London, UK.

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

The findings show that people can appear to be just as infectious after two doses of COVID vaccine. In other words, while vaccinated people recover faster from infection, their peak viral load (when they are most infectious) remains similar to that of unvaccinated people, implying that they can still easily spread the virus in household settings.

“Vaccination reduces the risk of infection with delta variants and speeds up viral clearance. Despite this, fully vaccinated individuals with breakthrough infections have peak viral loads comparable to unvaccinated cases and can efficiently transmit infection in household settings, including to fully vaccinated contacts. Early host-virus interactions may shape the entire viral trajectory “Lalvani explained.

Furthermore, the study found that susceptibility to infection increases just a few months after the second vaccine dose, emphasising the importance of booster shots.

Continued public health and social measures to prevent transmission, such as mask wear, social distancing, and testing, are thus important, even in vaccinated individuals, according to the study.