COVID-19 infections are rare and mild after vaccination

New research is showing that although some vaccinated people are still contracting COVID-19, they generally experience milder disease for a shorter period of time with a low viral load. The study, published in the New England Journal of Medicine, offers some of the first robust data tracking the severity of “breakthrough infections.”

Veteran BBC reporter Andrew Marr recently published an op-ed recounting his experiences of COVID-19. Marr was fully vaccinated, noting “I wasn’t behaving recklessly – but I did feel pretty much invulnerable”.

Marr’s story didn’t end in hospitalization, but instead describes a few days of fever, aches and flu-like symptoms. While some may read his story as an example of vaccine failure, it is in fact quite the opposite. At 61 years old Marr is without a doubt a prime example of someone at a high-risk of severe COVID-19, yet vaccination turned the disease into something that took him less than a fortnight to recover from.

“I recovered quite quickly and, it seems, completely,” Marr writes. “By the time my quarantine ended, I felt fine.”

A new study is offering some strong data on how vaccination can attenuate COVID-19 in the few people who still develop the disease. The research looks at data from two ongoing studies funded by the Centers for Disease Control and Prevention (CDC). Pfizer and Moderna mRNA COVID-19 vaccines were the only candidates used in the cohort studied.

The studies are following several thousand front-line workers, tracking infection and re-infection in vaccinated and unvaccinated subjects. Those involved in the study supply weekly nasal swab PCR tests, regardless of vaccination status.

Up to mid April 2021 the new research counted 204 SARS-CoV-2 infections in the entire cohort of 3,975. Only five of those infections occurred in fully vaccinated subjects and 11 infections were detected in partially vaccinated subjects (≥14 days after dose 1 and <14 days after dose 2).

This means full vaccination was 91 percent effective at preventing any kind of SARS-CoV-2 infection, symptomatic or asymptomatic.