COVID-19 Antibodies in Donated Plasma Decline Within First Months After Symptom Onset
The earlier plasma is collected after a donor’s recovery from coronavirus disease 2019 (COVID-19), the better, as antibodies start to disappear after 3 months of symptom onset, according to a study published in the journal Blood.
The results may also have implications for vaccine design and for prevalence studies in communities trying to gauge how many people have recovered from the virus.
“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, Héma-Québec, Montreal, Québec. “Based on our findings, antibodies against the new coronavirus are not eternal.”
“If antibodies wane 3 to 4 months after a peak of infection, we could underestimate the prevalence of the infection in communities or populations,” she added.
The small study, which drew from 282 COVID-19 plasma donors in Quebec, followed 15 adults (11 males and 4 females) who were diagnosed with and subsequently recovered from COVID-19. While symptoms ranged from mild to severe, none of the donors were hospitalised for their COVID-19 infection. Participants each donated their plasma between 4 and 9 times with the first donation occurring between 33 and 77 days after symptom onset and the last donation between 66 and 114 days.
The decline in antibodies over time appears unrelated to the number of times someone donated blood plasma and is, instead, due to the elapsed time since the infection and a natural waning of the immune response. All 15 donors showed decreases in antibodies at the same time, around 88 days, and half of the detectable antibodies decreased 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.
She noted that nearly 7% of the original 282 donors did not have detectable antibodies at their first donation and this proportion doubled when considering donors who waited more than 11 to 12 weeks after symptom onset before donating.
“Based on our findings, clinicians should ideally use plasma that is collected early on after a donor’s onset of symptoms and check for the presence of antibodies before giving donor plasma to a patient,” said Dr. Bazin.
SOURCE: American Society of Hematology