Vaccinated People Easily Transmit COVID-19 Delta Variant in Households: UK Study

MELBOURNE, AUSTRALIA - JULY 20: Staff are seen preparing AstraZeneca vaccine doses inside the Melbourne Showgrounds COVID-19 Vaccination Centre on July 20, 2021 in Melbourne, Australia. Premier Daniel Andrews has announced a 7 day extension on the lockdown in Victoria, as the state continues to record new community COVID-19 cases and work to stop the spread of the highly infectious delta coronavirus strain in the community. Photo by Daniel Pockett/Getty Images

The Delta COVID-19 variant can easily transmit from vaccinated people to their household members, said a recent UK study, although its researchers concluded that vaccinations and boosters are the way forward.

A year-long study from the Imperial College London published in The Lancet on Thursday found that the Delta variant is still highly transmissible within a vaccinated population.

“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,” Dr. Anika Singanayagam, co-lead author of the study, said in a statement.

The findings, Singanayagam added, provide some insight into why the Delta variant is “continuing to cause high COVID-19 case numbers ... even in countries with high vaccination rates.”

An analysis found that the viral load declined most rapidly for those who were vaccinated with the Delta variant compared with those who are unvaccinated, according to the researchers.

But the peak levels of the CCP (Chinese Communist Party) virus, which causes COVID-19, in vaccinated people were similar to levels in unvaccinated people, they found, adding that it might be the reason why the Delta variant can spread despite vaccination.

Because the Delta variant can spread easily among vaccinated people, another researcher involved in the study, Dr. Ajit Lalvani, argued it is necessary for people to get the vaccine or boosters to reduce severe COVID-19 symptoms.

“We found that susceptibility to infection increased already within a few months after the second vaccine dose ... so those offered a booster should get it promptly,” Lalvani said.

Their study, which surveyed 621 participants, found that of 205 household contacts of people who had the Delta infection, about 38 percent of household contacts who were not vaccinated tested positive, compared with 25 percent who tested positive among vaccinated household contacts.

Immunity from full vaccination also dropped in as little as three months, their research also found. They didn’t say whether it should inform the UK’s booster policy.

However, amid the push to get large swaths of the population vaccinated, some immunologists and doctors have argued that natural immunity needs more research and should be factored into policy decision-making.

Steve Templeton, an immunologist with Indiana University’s school of medicine, wrote that “the key to ending the pandemic has always been the immune system.”

“The fact that so many have recovered from infection and that robust, durable, and protective immunity in those individuals has been unequivocally proven should be considered a good thing,” he said in an article dated Oct. 22, adding that “there appears to be a drive to cancel the term ‘natural immunity,’ a pretense that the vaccinated need fear the unvaccinated, and an unwillingness to treat the public as adults that can handle nuanced information and make decisions regarding their health.”