An outbreak of COVID-19 on a fishing boat has provided scientists with the first direct evidence that antibodies actually protect humans from re-infection.
More than 100 of the 122 crew members on board the ship were infected; but three sailors who had antibodies to the new coronavirus in her blood prior to the trip – indicating an infection in the past – the virus did not catch on a second time. These antibodies target the “spike protein” to SARS-CoV-2 that the virus uses to invade human cells.
Although scientists believe that having antibodies, in particular so-called ‘neutralizing antibodies’, would provide protection against COVID-19, they do not have studies in humans to do so.
“This is the first time to show that having these antibodies is a correlative to protection in humans,” studied former author Dr. Alex Greninger, an assistant professor of laboratory medicine and pathology at the University of Washington School of Medicine, said in a video released by the university.
The findings could be good news for candidate COVID-19 fax, who are generally trying to get the immune system to produce neutralizing antibodies against the virus, the authors said.
The study was posted to the pre-print database on August 14th medRxiv, and has not yet been published in a peer-reviewed journal.
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The researchers of the study examined samples taken from crew members before and after the trip. Before the boat left Seattle in May, all 122 members were tested for SARS-CoV-2, the virus that causes COVID-19, and none tested positive. Only three members were found neutralizing antibodies, which block the virus from infecting cells.
The boat’s COVID-19 tests did not stop infections from breaking out during the voyage, and the ship returned to sea after 18 days. A second round of testing revealed that more than 85% of crew members were infected with COVID-19.
Overall, 103 of the 117 crew members without neutralizing antibodies were infected during the departure of the boat during the voyage, compared to zero of the three members with neutralizing antibodies.
“This virus has shown the potential to infect many people on boats since the beginning of the pandemic,” Greninger said. “In a way, we turn the tide on the ships here, we use them to learn things about our ability to protect ourselves.”
The authors acknowledge that their study was small, with only three people having had anti-anemia prior. But the results were statistically significant, which means that there is a low chance that they are due to chance.
“Just looking at the numbers, it becomes clear that it is unlikely that all three of these people were protected by chance,” said Florian Krammer, an immunologist at the Icahn School of Medicine at Mount Sinai in New York. The New York Times.
The study also cannot determine how long antibodies would provide protection, and studies over longer periods will be needed to investigate this, Greninger said.
The study also does not explain how a little more than a dozen crew members apparently escaped infection without having prior immunity. It is possible that these crew members had jobs or behaviors that reduced the exposure, Greninger said The Seattle Times.
Originally published on Live Science.
