Unlocking the mystery of the "never COVID" cohort – Axios

Some people don't get COVID despite being exposed to the virus a mystery researchers are trying to unravel.

Why it matters: Understanding the small cohort of "never COVID" people could lead to new vaccine targets or other protections as the world enters the third year of the pandemic.

Driving the news: Using a highly debated method called a human challenge study, a British trial deliberately exposed people who were unvaccinated and had no evidence of prior infection by placing a droplet of SARS-CoV-2 in their nose. They found 16 out of 34 participants did not get infected, according to the pre-print paper posted recently.

The latest: Researchers are now trying to zero in on that question.

1. Cross-immunity from the four endemic human coronaviruses is one hypothesis. Those other coronaviruses cause many of the colds people catch and could prime B-cell and T-cell response to this new coronavirus in some people.

2. Multiple genetic variations may make someone's immune system more or less susceptible to the virus.

3. Mucosal immunity may play an underrecognized role in mounting a defense.

4. Where the virus settled on the human body, how large the particle was, the amount and length of exposure, how good the ventilation was and other environmental circumstances may also play a role, Openshaw says.

The bottom line: Vaccination and boosters, wearing masks, washing hands and good ventilation remain our most important tools in preventing infection or mitigating symptoms, Brooks says.

Editor's note: This story originally published on Feb. 10.

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Unlocking the mystery of the "never COVID" cohort - Axios