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Big Question on Immunity Remains 'an Unknown'

Study out of Shanghai suggests not everyone develops antibodies, but more data is needed
By John Johnson,  Newser Staff
Posted Apr 13, 2020 1:11 PM CDT

(Newser) – Much attention is paid to the growing death toll from the coronavirus, which was at more than 116,000 worldwide as of Monday afternoon. Less attention is paid to a different stat—the more than 440,000 people who have recovered. And related to that is a huge question: Are those recovered patients now immune from the disease? The answer will go a long way toward determining public policy until a vaccine arrives, but the latest research is anything but definitive. Coverage:

  • New study: Preliminary research on Shanghai patients show that some had no detectable antibodies after infection, the World Health Organization said Monday, reports CNBC. On the other hand, some had a high anitbody response, says the agency's lead COVID-19 scientist, Dr. Maria Van Kerkhove. The upshot: "With regards to recovery and then re-infection, I believe we do not have the answers to that," says another top WHO scientist, Dr. Mike Ryan. "That is an unknown."
  • Educated guess: Epidemiologist Marc Lipsitch warns in a New York Times op-ed that big decisions will have to be made on just "glimmers of data." He assesses research on other coronaviruses and offers this "educated guess" on COVID-19: Most infected people "will have an immune response, some better than others. That response, it may be assumed, will offer some protection over the medium term—at least a year—and then its effectiveness might decline." Lipsitch also warns that his very op-ed might be outdated soon.

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  • Ditto: At the Conversation, epidemiologist Tom Duszynski agrees that some kind of immunity is likely. "The question remains how long that immunity will last," he writes. "Other coronaviruses like SARS and MERS produce an immune response that will protect a person at least for a short time," he notes. "I would suspect the same is true of SARS-CoV-2, but the research simply hasn’t been done yet to say so definitively." Once a vaccine is distributed, people might need periodic booster shots.
  • Question marks: It's possible the virus can reactivate in some patients, though perhaps because it wasn't entirely eliminated from their system, says the WHO's Van Kerkhove. The possibility of the virus reactivating in recovered patients became clear with results out of South Korea, though it's possible false negatives skewed results. Also, some COVID-19 patients might be eliminating the main infection but developing a secondary bacterial issue, suggests Van Kerkhove.
  • Who is 'recovered'? In the US, the CDC standards are strict, writes Duszynski. People must be fever-free, naturally, for three consecutive days, and they must show improvement in symptoms such as coughing and shortness of breath after at least seven days. Plus, they must test negative twice within 24 hours before they are deemed to be recovered.
  • Vaccine: Ideally, the questions about whether recovered patients are immune will become less important once a vaccine is available. Bloomberg reports that more than 70 are now in development worldwide, and three of them already are in human trials. That is incredibly fast by normal standards, though a widely available vaccine is still thought to be a year or so away.
(Dr. Anthony Fauci says it's plausible that recovered patients in the US might receive some kind of immunity document.)

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