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After Recovery From the Coronavirus, Most People Carry Antibodies
A new study adds to evidence of immunity among those who have already been exposed to the pathogen. A new study offers a glimmer of hope in the grim fight against the coronavirus: Nearly everyone who has had the disease — regardless of age, sex or severity of illness — makes antibodies to the virus. The study, posted online on Tuesday but not yet reviewed by experts, also hints that anyone who has recovered from infection may safely return to work — although it is unclear how long their protection might last.
“This is very good news,” said Angela Rasmussen, a virologist at Columbia University in New York who was not involved with the work.
Antibodies are immune molecules produced by the body to fight pathogens. The presence of antibodies in the blood typically confers at least some protection against the invader.
Health officials in several countries, including the United States, have hung their hopes on tests that identify coronavirus antibodies to decide who is immune and can go back to work. People who are immune could replace vulnerable individuals, especially in high-transmission settings like hospitals, building what researchers call “shield immunity” in the population.
But most antibody tests are fraught with false positives — picking up antibody signals where there are none. The new study relied on a test developed by Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai, that has a less than 1 percent chance of producing false-positive results.
Several small studies have given reason to hope that people who have had Covid-19, the illness caused by the coronavirus, would gain some immunity for some period of time. The new study is the largest by far, with results from 1,343 people in and around New York City.
The study also eased a niggling worry that only some people — only those who were severely ill, for example — might make antibodies. In fact, the level of antibodies did not differ by age or sex, and even people who had only mild symptoms produced a healthy amount.
Having antibodies is not the same as having immunity to the virus. But in previous research, Dr. Krammer’s team has shown that antibody levels are closely linked with the ability to disarm the virus, the key to immunity.
“It really shows that most people do develop antibodies, and that there’s very good correlation between those antibodies and their capability to neutralize viruses,” Dr. Rasmussen said.
Researchers at Mount Sinai tested people who signed up to be donors of convalescent plasma, antibodies extracted from blood. The project has enrolled more than 15,000 people so far, according to Dr. Ania Wajnberg, who is leading the effort. The new study is an analysis of results of the first set of donors. Over all, only 3 percent of these participants had been seen in the emergency department or had been hospitalized. The remaining subjects had only mild or moderate symptoms.
“To my knowledge, this is the largest group of people described with mild disease,” Dr. Wajnberg said.
The criteria for inclusion became more stringent as the team learned more about the coronavirus. For example, they initially required the potential donors to be free of symptoms for only three days but later extended that to 14 days.
The team tested 624 people who had tested positive for the virus and had recovered. At first, just 511 of them had high antibody levels; 42 had low levels; and 71 had none. When 64 of the subjects with weak or no levels were retested more than a week later, however, all but three had at least some antibodies.
That suggests the timing of testing for antibodies can greatly affect the results, the researchers said. “We weren’t looking exactly at this, but we had enough to say that 14 days is probably a little too early,” Dr. Wajnberg said.
(Adapted from: www.www.nytimes.com)
Choose the correct Verb Tense for the underlined words on the sentence below:c
“Health officials in several countries, including the United States, have hung their hopes on tests that identify coronavirus antibodies to decide who is immune and can go back to work.”
