Fishing boat outbreak may offer insight into virus immunity

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Fishing boat provided unexpected insight into how antibodies can protect against coronavirus reinfection

Three crew members of a Seattle fishing boat who had antibodies capable of neutralizing the novel coronavirus remained uninfected during an epidemic that swept through the ship, making most people on board ill, reported researchers.

The small, real-world study, which has not been peer reviewed, is one of the first in humans to suggest a link between neutralizing antibodies – those that prevent the virus from attaching to host cells – and protection against infection.

Researchers at the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle screened 120 of 122 people before boarding the fishing boat in May, testing both for the active virus and for antibodies in the blood that would indicate a previous or current infection.

None of the crew members tested positive for the virus, but six had antibodies and of these, three had evidence of neutralizing antibodies.

More than two weeks after the boat left, he returned ashore with an infected crew member who needed hospital treatment.

The researchers then tested the entire crew for several weeks and found that 85% – 104 crew members – were infected.

But none of the three neutralizing antibodies tested positive and reported no symptoms during the outbreak.

“Therefore, the presence of neutralizing antibodies from a previous infection was significantly associated with protection against reinfection,” said the study authors.

– “Important information” –

Scientists have not been able to perform direct human tests to discover the protection conferred by neutralizing antibodies, due to ethical concerns about the potential severity and long-term impacts of the virus, the authors said. ‘study.

Danny Altmann, professor of immunology at Imperial College London, said the new study, although small, was a “remarkable, real human experiment at a time when we lacked formal and categorical evidence that neutralizes antibodies. genuinely offer protection against reinfection ”- although this has been predicted by animal experiments.

“In short, that’s good news. Who would have thought that research in immunology on fishing vessels could be so informative?” he added.

But research doesn’t necessarily show people can’t catch COVID-19 twice.

The three crews who had weaker antibodies before setting sail all tested positive on return – although the researchers said their initial results could have been a false positive or a sign of early infection.

In a commentary on the study, Jonathan Ball, professor of molecular virology at the University of Nottingham, said that this “suggests that people who have previously been exposed to the virus are likely to re-infect themselves unless they have levels appreciable neutralizing antibodies “.

Ball, who was unrelated to the research, said this “gives us important insight into the type of immunity that might protect against future infection,” but it doesn’t show whether or not past exposure can protect. against serious infection in people who do. not develop neutralizing antibodies.

klm / mh / tgb