Coronavirus: How fishermen landed a vital clue on Covid immunity

A US fishing vessel looking for a good haul instead found an answer to the most important Covid question we face.

A commercial fishing foray in the US could unlock the key to Covid immunity.

In May a fishing vessel headed out into Puget Sound, off Seattle, hoping for a good haul. When it returned, it brought back something far more valuable – an answer to the most important question facing the world.

On that ship, a study claims, was the first good evidence that being infected with coronavirus conferred immunity.

After setting off, one of the sailors came down with Covid-19. The vessel returned to port, where the health authorities discovered that 103 crewmates had also been infected.

Before sailing, all those on board had been screened, both for live infection and antibodies. Although this testing did not pick up the infected sailor, it picked up something else. Six tested seropositive, showing they could have had the infection. Of those, three had high levels of neutralising antibodies.

When the ship returned to dock, the authorities discovered that the three with a high level of antibodies were among the minority of 18 crew who had not been infected. It is possible that the other three, who did get infected, were false positives.

Among those who had not had it, more than 85 per cent were infected. Among those who almost certainly had, and had a strong reaction, none were.

By showing that a decent level of antibodies offers protection, the findings strongly suggest that the leading vaccine contenders will do as well.

“It would have been catastrophic for the world if we had not seen this,” said Alex Greninger, from the University of Washington, who published the research before peer review in Medrxiv.

The presence of neutralising antibodies has been one of the targets of vaccine trials. “It is a big deal to show if those antibodies are protective,” he said.

He said it was a sign of how new the virus was that a study of three salmon fishermen in Seattle was the best evidence for this yet.

“With tens of millions of infections across the world, I expected someone to see this first,” he added.

The Times