Family members of an infected person are primarily infected with covid: the main factor of infection is prolonged daily contact. However, it was previously unknown whether vaccination affects the likelihood of transmission of the virus.
A new article in The Lancet, from Imperial College London and the UK Health Protection Agency (HSA), shows that fully vaccinated people infect their loved ones in the same way as those without a dose. That is, vaccination is critical to prevent serious illness and death, but it does not reduce transmission of the virus in case of infection. Reported by The Guardian.
The authors of the work analyzed the data of 204 relatives of 138 people who were infected with the delta variant. 53 relatives eventually became infected. Of these, 31 were fully vaccinated, 15 did not receive a single dose. The results show that even those who are fully vaccinated have a high risk of becoming infected. The probability of infection in an unvaccinated relative is 38%, in a fully vaccinated relative - 25%. At the same time, the fact of vaccination of the source of infection has practically no effect on how infectious it is for your family.
The peak viral load in infected people was the same whether they were vaccinated or not. However, in the vaccinated, it decreased faster, that is, they quickly get rid of the infection.
The study also showed that as early as three months after the second dose of the vaccine, the risk of infection was higher compared to more recent vaccinations. This suggests that protection begins to weaken about three months after vaccination. This highlights the importance of the booster vaccine.