City health officials warn that anti-coronavirus antibody tests may not prove immunity


New York City health officials advise healthcare providers not to use antibody tests to determine coronavirus infections or potential immunity.

Serological tests, as they are called, are too unreliable and it is not yet known whether antibody detection results in immunity against COVID-19, according to a letter dated April 22 from Demetre Daskalakis, an assistant commissioner at the city’s health department.

“They can produce false negative or false positive results, the consequences of which include providing incorrect advice to patients on preventive interventions such as physical distance or protective equipment,” Daskalakis wrote in the letter.

With so much uncertainty about the asymptomatic carriers of the virus and the number of people actually infected, attention has turned to antibody testing in the hope that it may help shed light on who actually caught the virus. viruses and if they are now immune.

Daskalakis cautioned that medical providers should not assume that the tests currently on the market are “reliable enough to be used in routine clinical practice” and that some people incorrectly claim that they have been approved for use by the FDA.

“A dose of reality,” said Councilor Mark Levine (D-Manhattan), chair of the council’s health committee, who shared the letter on social media Thursday evening.

“There is irrational exuberance in antibody testing,” Levine tweeted. “They are useful for tracking trends in the general population, but should * not * be used to make personal health decisions.”

Levine added, however, that the tests still had a purpose in the fight against the pandemic.

“However, anti-body tests remain extremely useful in determining whether volunteers can donate plasma to patients who are still fighting Covid,” he said.

Serological tests are not reliable for diagnosing viruses because the antibody response can take days or weeks to be detectable, which means that a newly infected person could still be negative, depending on the city.

The letter was sent just a day before the state announced the preliminary results of its own antibody study showing that 2.7 million New Yorkers may have been exposed to the coronavirus.

Governor Andrew Cuomo is pushing for more widespread antibody testing, saying it is a key to restarting the economy as it would indicate which workers may have acquired some immunity to the virus.

But others, like the White House coronavirus expert, Dr. Anthony Fauci, have warned against over-reading the tests at this point, in part for the same reasons as the city.

“There is an assumption – a reasonable assumption – that when you have an antibody you are protected against reinfection, but this has not been proven for this particular virus. This is true for other viruses, “he said earlier this week.


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