According to a study published in The Lancet Infectious Diseases journal it has been found that people who are fully vaccinated can contract and pass on Delta variant of SARS-CoV-2, the virus that causes coronavirus, in household settings, but at lower rates than people who are not vaccinated. A study conducted by the researchers led by Imperial College London, UK, found that immunized people clear the infection more quickly, but the peak viral load among them is similar to that seen in unvaccinated individuals, which may explain why they can still readily pass on the virus at home.
Most of the coronavirus transmission is known to take place in households even if there is limited data on the risk of transmission of the Delta variant from vaccinated people with asymptomatic or mild infections in the community.
The researchers noted that most COVID-19 transmission is known to occur in households yet there is limited data on the risk of transmission of the Delta variant from vaccinated people with asymptomatic or mild infections in the community.
Professor Ajit Lalvani of Imperial College London, who co-led the study said, ‘Vaccines are critical to controlling the pandemic, as we know they are very effective at preventing serious illness and death from COVID-19.’
‘However, our findings show that vaccination alone is not enough to prevent people from being infected with the Delta variant and spreading it in household settings,’ Lalvani added.
The experimenters noted that the transmission between vaccinated people makes it essential for unvaccinated people to get immunised to cover themselves from acquiring infection and severe Covid-19, especially as further people will be spending time outside in close propinquity during the downtime months.
The study enrolled 621 actors, linked by the UK contact tracing system, between September 2020 and September 2021. All actors had mild Covid-19 illness or were asymptomatic. They had diurnal PCR tests to descry infection, anyhow of whether or not they had symptoms. The experimenters performed PCR tests on tar samples handed daily by each party for 14 – 20 days. Changes over time in viral cargo– the quantum of contagion in a person’s nose and throat– were estimated by modelling PCR data.
An aggregate of 205 ménage connections of Delta variant indicator cases were linked, of whom 53 tested positive for Covid-19. Among vaccinated connections infected with the Delta variant, the median length of time since vaccination was 101 days, compared with 64 days for uninfected connections, the experimenters said.
This suggests that the threat of infection increased within three months of entering a alternate vaccine cure, probably due to waning defensive impunity, they said. The authors point to vaccine waning as important substantiation for all eligible people to admit supporter shots.
An aggregate of 133 actors had their diurnal viral cargo circles analysed, of whom 49 hadpre-Alpha variant and were unvaccinated, 39 had Nascence and were unvaccinated, 29 had Delta and were completely vaccinated, and 16 had Delta and were unvaccinated. The study plant that the viral cargo declined more fleetly among vaccinated people infected with the Delta variant compared with unvaccinated people with Delta, Alpha, orpre-Alpha.
Still, the authors note that vaccinated people didn’t record a lower peak viral cargo than unvaccinated people, which may explain why the Delta variant can still spread despite vaccination as people are most contagious during the peak viral cargo phase.
“Understanding the extent to which vaccinated people can pass on the Delta variant to others is a public health priority,” said Anika Singanayagam, co-lead author of the study.
“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,” Singanayagam said. The findings suggest that continued public health and social measures to curb transmission – such as mask wearing, social distancing, and testing – remain important, even in vaccinated individuals.