COVID-19 Antibodies in Donated Plasma Decline Within First Months After Symptom Onset: Study

The earlier plasma is collected after the donor's recovery from coronavirus, the better; as antibodies started to disappear after three months of symptom onset, revealed research.

The results have implications for vaccine design and how many people have recovered from COVID-19, are published today in the journal Blood.

Coronavirus
Coronaviruses infect animals, humans, and birds. Human coronaviruses, such as SARS, MERS, and 2019-nCoV cause respiratory distress and even death. The S protein is the infectious agent of the virus.

‘Clinicians should use plasma collected early on after a donor's onset of symptoms and check for the presence of antibodies before giving donor plasma to a patient.’

In convalescent plasma treatment, people newly ill with COVID-19 receive plasma from a recovered person hoping that the therapy will bolster their ability to fight off the virus and limit its severity.

"While many clinical trials are underway to better understand whether convalescent plasma is clinically beneficial for treating COVID-19, a key question is at what time point is it most effective to collect donor plasma based on the presence of antibodies that help fight the virus," said Renée Bazin, PhD, of the Héma-Québec blood center (Canada) and author of the study. "Based on our findings, antibodies against the new coronavirus are not eternal."

282 COVID-19 plasma donors in Quebec, Canada, followed 15 adults (11 males and 4 females) diagnosed with and subsequently recovered from COVID-19 were recruited for the study.

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While symptoms ranged from mild to severe, none of these donors were hospitalized for their COVID-19 infection. Participants each donated their plasma between four and nine times, with the first donation occurring between 33 and 77 days after symptom onset and the last donation between 66 and 114 days.

This study showed that seropositive people (produced antibodies against the virus that causes COVID-19) become seronegative (no detectable antibodies after a certain point).

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All 15 donors showed decreases in antibodies simultaneously, around 88 days, and half of the detectable antibodies reduced within 21 days afterward.

"The antibodies disappear rapidly, so people recovering from COVID-19 who want to donate blood plasma should not wait too long once they become eligible to donate," said Dr. Bazin.

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Nearly 7% of the original 282 donors did not have detectable antibodies at their first donation. This number doubled when considering donors who waited more than 11 to 12 weeks after onset of symptoms before donating.

"Based on our findings, if antibodies wane three to four months after a peak of infection, we could underestimate the prevalence of the infection in communities or populations," said Dr. Bazin.

Researchers have planned to follow plasma blood donors over time; future studies will determine if a specific plasma is more beneficial.

Source-Medindia