Researchers conducting trials on the effectiveness of an antibody-dependent treatment for COVID-19 say they’re not worried about a report from the World Health Organization (WHO) casting doubt around how long antibodies may last.
READ MORE: Canadian Blood Services exploring using blood plasma from survivors to treat COVID-19 patients
In a scientific brief in its Saturday COVID-19 update, WHO warned that there’s “no evidence” that recovering from the virus prevents someone from falling ill again because of it.
“There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection,” WHO said in a warning meant as an advisory to governments to not offer so-called “immunity passports” to individuals that have recovered from the coronavirus, allowing them to be exempt from quarantines and other social restrictions. (Chile is the first country expected to move ahead with the idea)
“WHO is right, there’s no evidence that you will be permanently immune if you’ve had COVID-19 once,” said Delphine Denis, a spokesperson for the Canadian Blood Services (CBS).
A team of researchers from across Canada, which includes academic physicians and doctors from CBS and Héma-Québec (Quebec’s blood agency), are in the early steps of a study of if blood plasma taken from people who recovered from COVID-19, which contain antibodies to the illness, could be given to patients with existing cases to help them recover.
“(The WHO’s declaration) does not impact our clinical trial to test the safety and effectiveness of COVID-19 convalescent plasma as a possible treatment to help patients with the virus,” Denis said.
Dr. Philippe Bégin, the lead immunologist on CONCOR (the research team looking into convalescent plasma treatment for COVID-19), said that while the WHO’s guidance does not point to success or failure for his group’s study, that it does have relevance to it.
Bégin said that when someone gets an infection, their body’s peak production of antibodies happens at about four weeks before plateauing for three months and then shrinking to long term levels.
READ MORE: Doctor says SARS tests offer encouraging lesson on treating COVID-19 with plasma
“(This level) may or may not be enough to confer protection,” he wrote to iPolitics in an email.
For these reasons, blood will only be collected in the convalescent plasma study from people shortly after they’ve recovered from the disease, so there isn’t time for their concentration of antibodies to go down.
“(CONCOR) put an arbitrary cut-off of 12 weeks but will follow closely the evolution of antibody levels in donors to readjust,” Bégin said.
He also said there is a challenge posed in measuring the potency of antibodies because they can exert protective functions in multiple ways – some which can be easily measured and some that can’t.
“We will also be testing various antibody potency tests on plasma as part of the study to establish what are the best methods to select the most effective convalescent plasma,” Bégin said.
CBS is expecting to collect its first COVID-19 convalescent blood plasma donation on Wednesday.
Convalescent blood plasma (that which is taken from recovered patients) was used as a treatment during the Spanish Flu of a century ago and in a small study was shown to be a helpful therapy for SARS patients.
If effective against COVID-19, the treatment would be one of the first proven means of treating the novel coronavirus.
READ MORE: Canadian Blood Services to collect first COVID-19 convalescent plasma donation on Wednesday
“The results from the clinical trial will inform future decisions on the wider availability of convalescent plasma. It will be an important contribution to research on a global scale that could help patients in Canada and around the world,” Denis said.
With files from Marco Vigliotti
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