A study led by Argentine scientists has found that giving convalescent blood plasma from recovered Covid-19 patients to others who have been recently infected can significantly reduce the risks of them becoming critically ill – but only if it is administered within the first 72 hours of contracting the disease.
“We understand that the plasma is useful in the first three days of the illness, that is to say, you have [a period of] 72 hours of symptoms [in which] to receive it,” infectious disease specialist Dr Fernando Polack, who led the trial, told Radio Con Vos on Thursday.
Convalescent plasma, a light-yellow liquid in the blood that remains once it has been stripped of its red and white blood cells, usually contains disease-fighting antibodies.
The study, published in The New England Journal of Medicine last Wednesday, assessed the results of the early administration of plasma with a high content of antibodies to prevent severe forms of Covid-19 in older adults. It found that the risk of being critically ill could be reduced by close to half.
“It’s an option if someone over 65 becomes infected, but it’s like health insurance – you have to have it when you’re healthy because there is no time to wait and see what happens. If you are already unwell, the plasma is useless,” Polack said.
The doctor explained that results depend on the amount of antibodies present in the plasma. “The best providers are the patients that were hospitalised because they have more antibodies, and the people who were vaccinated,” he noted, defining the latter group as “potential privileged donors.”
“In a society with low defences against the virus, to be vaccinated is to be protected and also to have the possibility of donating plasma, which means six treatments for six elderly people for each person who donates twice a month,” according to the infectologist.
Polack led the team of scientists at the Fundación Infant, who carried out the study in collaboration with public hospitals and private institutions between June and October 2020. The physician created the foundation in 2003 in order to study childhood respiratory diseases.
The study involved 200 plasma donors and 120 volunteer patients (half of which were treated with a saline solution placebo), as well as more than 200 healthcare professionals.
Government officials hailed the results in a press release, though Argentina currently does not have the capacity in its health system to make use of this novel treatment.
“It is something under construction within the public and private system. A huge stock [of plasma] has to be generated as a bridge until there is a vaccine for most of the population,” Polack explained.
The infectologist said that when vaccination reaches a certain threshold, the convalescent plasma treatment will lose importance. He cites measles, chickenpox and hepatitis as examples of diseases where widespread vaccination programmes render plasma treatments obsolete.
“There is plasma for measles, chickenpox and hepatitis, but no-one hears about it because there is a vaccine,” he said.
Argentina began vaccinating against Covid-19 on December 29, with 300,000 initial doses of Russia’s Sputnik V shot. The country’s health authorities have also approved vaccines developed by Pfizer-BioNTech and the Oxford-AstraZeneca.
To date, the country has recorded more than 1.7 million confirmed cases and more than 44,000 fatalities.