New antibody study: “study eased a niggling worry that only some people might make antibodies. In fact, level of antibodies did not differ by age/sex, and even people who had only mild symptoms produced a healthy amount”. Results from NYC. #COVID19 https://www.nytimes.com/2020/05/07/health/coronavirus-antibody-prevalence.html

2) “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.” Pretty decent

3) “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.”

4) “tested 624 people who had tested positive 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/no levels were retested >1week later, however, all but three had at least some antibodies.”

5) “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.”

6) “There was even a difference between levels at 20 days versus 24 days, she said, suggesting that the optimal time for an antibody test is well after symptoms begin. “What we’re telling people now is at least three weeks after symptom onset,” Dr. Wajnberg said.”

7) Because tests to diagnose infection were unavailable to most people in New York City in March, the researchers included another 719 people in their study who suspected they had #Covid19 based on symptoms and exposure to the virus, but in whom the illness had not been diagnosed

8) In this group, the researchers found a different picture altogether. The majority of these people — 62 percent — did not seem to have antibodies. many probably mistook influenza, another viral infection or even allergies for Covid-19, Dr. Wajnberg said.

9) An antibody survey conducted by New York State officials found that 20 percent of city residents had been infected.

10) “Another finding from the study — that diagnostic PCR tests can be positive up to 28 days after the start of infection — is also important, Dr. Wang said. These tests look for genetic fragments, not antibodies, and suggest an active or waning infection.”

11) “She and other scientists said it was highly unlikely that a positive test so long after symptoms appeared represents infectious . Researchers in SK recently announced several suspected cases of “reinfection” were a result of PCR tests picking up remnants of dead virus.”

12) “Genetic material from measles virus can show up in tests six months after the illness. And genetic fragments of Ebola and Zika viruses persist even longer.
Still, “Until we do know, it’s prudent for everyone to proceed as if a positive PCR test means contagious virus.”

13) “Experts said the next step would be to confirm that the presence of antibodies in the blood means protection from the coronavirus. The body depends on a subset of antibodies, called neutralizing antibodies, to shield it from the coronavirus...

14) “The question now becomes to what extent those are neutralizing antibodies and whether that leads to protection from infection — all of which we should presume are yes,” said Sean Whelan, a virologist at Washington University in St. Louis.

15) “tested whether the antibodies have neutralizing power. The researchers found that in about a dozen people, including some who had mild symptoms, the level of antibodies in the blood corresponded to the level of neutralizing activity....

16) “So everyone who makes antibodies is likely to have some immunity to the virus, Dr. Krammer said: “I’m fairly confident about this.”

Another way to assess immunity would be to show that purified antibodies can prevent coronavirus infection in an animal.

17) “But perhaps the most urgent question, especially as research on vaccines ramps up, is how long that immunity might last.
Even if the levels of antibodies fall over time to undetectable levels, people may still retain some protection from the coronavirus...

18) Immune cells called T cells are valuable soldiers in fighting pathogens, and one study has shown that coronavirus provokes a strong response from these cells. So-called memory cells, or B cells, may also kick into gear when they encounter , churning out more antibodies.

19) “Ultimately, however, the answer to how long immunity lasts will come only with patience.” ie we need to wait.

Remember folks - this pandemic has a fog of war. We don’t know everything yet. And science is resolving them. But science isn’t overnight magic. Wait for facts.