Study finds vaccinated as likely to spread COVID delta variant in households as unvaccinated

A new study released on Friday found that people who have been vaccinated against COVID-19 are every bit as likely to spread the delta variant of the virus as those who have not been vaccinated.

The study, which was published in The Lancet Infectious Diseases, also found that those who contracted the coronavirus had a very similar viral load whether or not they had been vaccinated. Researchers also found that about a quarter of vaccinated households contracted the virus while some 38 percent of non-vaccinated people caught the disease.

To reach their conclusions, researchers analyzed data from 621 participants in the United Kingdom over the course of one year.

“Although vaccines remain highly effective at preventing severe disease and deaths from COVID-19, our findings suggest that vaccination is not sufficient to prevent transmission of the delta variant in household settings with prolonged exposures,” said the study.

By contrast, scientists found that COVID vaccines were between 40 and 50 percent more effective at curbing transmission of the alpha variant within the household.

“Increasing population immunity via booster programmes and vaccination of teenagers will help to increase the currently limited effect of vaccination on transmission, but our analysis suggests that direct protection of individuals at risk of severe outcomes, via vaccination and non-pharmacological interventions, will remain central to containing the burden of disease caused by the delta variant,” noted the study.

The study was published as the U.S. is experiencing a major decline nationwide in coronavirus cases, though health experts are not certain that will be permanent or if new cases will surge again this winter.

Scott Gottlieb, the former Food and Drug Administration chief, predicted earlier this month that the “pandemic phase” of the virus will be over following approval of oral antivirals as well as COVID vaccines for kids and that the U.S. would soon enter the “endemic” phase as most Americans learn to simply deal and live with the disease.

The UK study also comes amid research published Friday by the Centers for Disease Control and Prevention, which found that vaccinated people are less likely to become reinfected with the virus than those who have already contracted it and thought to have natural immunity.

“We now have additional evidence that reaffirms the importance of COVID-19 vaccines, even if you have had prior infection,” CDC Director Dr. Rochelle Walensky noted in a statement. “This study adds more to the body of knowledge demonstrating the protection of vaccines against severe disease from COVID-19.”

The agency’s study involved more than 7,000 people across nine states and 187 hospitals and compared those who had not been vaccinated by contracted the virus over the previous three to six months versus those who were vaccinated during the same time frame.

Researchers discovered that those who were hospitalized with COVID-19-like symptoms were more than five times more likely to then test positive for the virus if they had experienced a previous infection than if they had been vaccinated recently.

Earlier this week, Walensky said during a press briefing that hospitalization rates for people who have not been vaccinated for the virus are roughly 12 times higher than for vaccinated people.

She also noted that the vaccination rate for all Americans over the age of 12 is about 78 percent of those who have taken at least one shot. That leaves around 60 million Americans who have not yet gotten vaccinated, she added.

Missy Halsey


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