‘Epsilon’ Variant Not More Common in mRNA-vaccinated Healthcare Workers

(Reuters Health) – SARS-CoV-2 breakthrough infections were rare in a cohort of fully vaccinated California healthcare workers and the Epsilon variant of concern was no more likely than other versions of the virus to cause them, a new study finds.

An analysis of data from more than 23,000 healthcare personnel who received at least one dose of an mRNA-based SARS-CoV-2 vaccine turned up a total of 189 post-vaccination COVID-19 cases, with 114 among those who were early-post-vaccination, 49 who were partially vaccinated, and 26 who were fully vaccinated.

After adjusting for community prevalence of the B.1.427/B.1.429 variant that was first detected in California and is called Epsilon in the World Health Organization naming system, the risk of breakthrough cases was not greater with the Epsilon variant, according to the results in Clinical Infectious Diseases.

“This is another study adding to the mounting pile of evidence showing that these vaccines are incredibly effective even in a real world setting,” said the study’s lead author, Dr. Karen Jacobson, a postdoctoral medical fellow in the division of infectious diseases and geographic medicine at Stanford University. “Breakthrough infections are not unexpected. But I think it’s really important to keep track of them and to make sure we’re not seeing a higher proportion of new variants in the breakthrough cases.”

There was no obvious factor that explained why certain of the fully vaccinated healthcare workers became infected, Dr. Jacobson said. “There wasn’t anything that jumped out as different about them. They didn’t seem to be older. There was no gender difference. We think most of the transmission was in the community. Our research spanned a time of really high community transmission.”

“In this dataset we didn’t have access to antibody data and there were no lab measures of immunity,” Dr. Jacobson said.

To take a closer look at breakthrough infections in vaccinated people, Dr. Jacobson and her colleagues collected demographic and clinical information from post-vaccine SARS-CoV-2 cases among healthcare personnel who had received at least one dose of an mRNA vaccine between December 18, 2020 and April 2, 2021.

The median age of those with breakthrough infections was 38, and 125 were female. Just seven had immunocompromising conditions, three of whom were positive for the virus early post-vaccination, two after partial vaccination, and two after full vaccination. Seventy-six reported a household contact with SARS-CoV-2 infection at the time of their positive COVID-19 test. The majority of positive tests occurred during the winter COVID-19 surge in northern California.

The researchers also tested a subset of samples for mutations characteristic of specific virus variants, including the L452R mutation that is a signature of the Epsilon variant. Of 261 available samples from vaccinated and unvaccinated healthcare personnel, 103 (39.5%), including 42 post-vaccination individuals (36.5%), were infected with the Epsilon variant.

The study findings didn’t surprise Dr. Waleed Javaid, director of infection prevention and control at Mount Sinai Downtown in New York. “What’s important is that healthcare workers who got post-vaccination infections – their numbers were pretty small,” Dr. Javaid said.

While the risk of infection isn’t zero, you have to remember that there are many things we do in life – such as driving a car – that carry some risk, Dr. Javaid said. “About 50 to 80 people per million die in motor vehicle accidents,” he added. “That doesn’t mean we stop driving cars.”

“Putting this in perspective, we are all taking chances whatever we do as we live our lives,” Dr. Javaid said. “With vaccination, the chances of being infected are reduced below the risks we take during our normal daily activities.”

SOURCE: https://bit.ly/3wSUZxt Clinical Infectious Diseases, online June 17, 2021.

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