This Trawler’s Haul: Proof That Antibodies Block the Coronavirus

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This Trawler’s Haul: Evidence That Antibodies Block the Coronavirus

A fishing vessel that left Seattle in May returned with an unexpected catch: the first direct human evidence that antibodies to the coronavirus can prevent infection.

More than a hundred crew members on board the American dynasty were affected by the infection over 18 days at sea. However, according to a new report, three sailors who originally carried antibodies remained virus-free.

Although the study is small, it addresses one of the most important questions of the pandemic: whether the immune response to a fight with the virus protects against re-infection.

"Knowing the answer to that question is critical to vaccine design and epidemiology," tweeted Jesse Bloom, evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle and one of the study's authors.

The study went online last week and has not yet been published in a peer-reviewed journal. Still, the result sparked optimistic chatter among scientists who relied on monkey studies to prove the effectiveness of antibodies.

"I found it very exciting – good enough to tell my family about it," said Michal Tal, an immunologist at Stanford University who was not involved in the work.

Several research teams have reported that exposure to the virus induces a robust immune response in most people, including those who may have been mildly ill. And the vaccine candidates currently in trials also appear to produce strong neutralizing antibodies that can block the virus.

However, the amount of these antibodies needed to prevent the virus from returning is unclear. Scientists measure neutralizing antibodies in titers, an indication of their concentration in the blood.

The three sailors who remained protected from the virus had very different titers; two were only in moderate amounts, a finding the researchers found reassuring.

"People were so concerned about the titers and the falling titers," said Dr. Alexander Greninger, a virologist at the University of Washington in Seattle.

The results show that even moderate titers prevented re-infection in a situation where exposure to the virus was high. He said, “These are reachable titers, right? Hopefully it helps to see and makes me very optimistic about the vaccines. "

The American dynasty carried 113 men and nine women. All crew members had been tested for viruses and antibodies as part of a routine pre-sailing screening. (The researchers did not have access to the results of two members.)

The trawler returned to shore after 18 days at sea when a crew member became sick enough to be hospitalized. The seafarers were tested again for the presence of viruses and antibodies for up to 50 days after their return.

The three seafarers who were confirmed to have neutralizing antibodies did not test positive for the virus during the study. 103 of the remaining 117 were infected.

These numbers may be small, but they are of great importance, said Dr. Greninger.

"A lot of people who see this say, 'Oh come on, it could be a coincidence," he said. In fact, the likelihood that the results are just coincidental is extremely slim, he added.

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frequently asked Questions

Updated August 17, 2020

  • Why does it help to stand three feet away from others?

    • The coronavirus spreads mainly through droplets from your mouth and nose, especially when you cough or sneeze. The C.D.C., one of the organizations using this measure, bases its six-foot recommendation on the idea that most of the large droplets that people make when they cough or sneeze fall within six feet of the ground. But six feet has never been a magical number that guarantees complete protection. For example, sneezing, according to a recent study, can trigger droplets that are far farther than two meters away. It's a rule of thumb: it is best to stand six feet apart, especially when it's windy. But always wear a mask even if you think they are far enough apart.
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    • As of now, this seems likely for at least a few months. There have been appalling reports of people apparently suffering from a second attack of Covid-19. However, experts say these patients may have a protracted course of infection, with the virus taking a slow toll weeks to months after initial exposure. People infected with the coronavirus typically produce immune molecules called antibodies, which are protective proteins made in response to an infection. These antibodies may only last in the body for two to three months, which may seem worrying, but that's perfectly normal after an acute infection subsides, said Dr. Michael Mina, an immunologist at Harvard University. It may be possible to get the coronavirus again, but it is highly unlikely to be possible in a short window of time after the initial infection or make people sick the second time.
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    • Many schools are unlikely to return to a normal schedule this fall that will require online learning, makeshift childcare, and stunted work days to continue. California's two largest public school districts – Los Angeles and San Diego – announced on July 13 that classes would only be held remotely this fall, citing concerns that the rise in coronavirus infections in their areas is too great Poses risk to students and teachers. Together, the two districts enroll around 825,000 students. They are the largest to date in the country, abandoning plans for a partial physical return to classrooms when they reopen in August. For other districts, the solution is not an all-or-nothing approach. Many systems, including the largest in the country, New York City, are developing hybrid plans where some days are spent in classrooms and some days online. There is still no national guideline on this. Therefore, check regularly with your city school system about what is going on in your community.

Other experts agreed. "If you just look at the numbers, it becomes clear that it is unlikely that all of these three people were protected by accident," said Florian Krammer, an immunologist at the Icahn School of Medicine on Mount Sinai in New York.

Dr. Krammer and colleagues are tracking antibody levels in people who have recovered from the coronavirus to determine at what point they may be susceptible to re-infection. The team started with people in New York, but the virus is circulating in the city at such a low level that Dr. Krammer and his colleagues had to expand the study to other locations.

Data from vaccine trials also identify the antibody titers required to disarm the virus. In the meantime, "this is the first evidence in humans," said Dr. Krammer. "It made my weekend."

The study raised other questions. Based on the Abbott Architect assay, six of the 120 people tested prior to the boat's departure had antibodies to the virus, suggesting prior exposure.

However, when the researchers re-analyzed these samples using more complex tests, it was confirmed that only three of the six contained antibodies, suggesting that three test results were false positive.

The Abbott test states that fewer than one false positive will be returned for every 100 samples. "That's a little worrying that the Abbott may be a little less specific than we thought," said Dr. Valley.

The researchers also looked at antibodies in the blood, as most teams do. However, these levels may not match those found in the nose or saliva, the two main entry points for infection, added Dr. Valley added.

"We're looking in the wrong place," she said. "If we want to look at protection against re-infection, we have to look up the nose."

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