Researchers at the Mayo Clinic report a strong hint that COVID-19 survivors’ blood plasma is helping other patients recover, but this is not evidence and some experts are worried if they will ever receive a clear answer in the wake of treatment. .
More than 64,000 patients in the U.S. have received convalescent plasma, a century-old approach to protect against flu and knives before vaccinations. It is a go-to tactic when new diseases appear, and history suggests that it works against some, but not all, infections.
There is still no solid evidence that it covers against the coronavirus and, if so, how it can best be used. But preliminary data from 35,000 patients treated with plasma coronavirus provide what Mayo lead researcher Dr. Michael Joyner on Friday called “signals of effectiveness”.
There were fewer deaths among people who received plasma within three days of diagnosis, and also among those given plasma that contained the highest levels of anti-antibodies for fighting strokes, Joyner and colleagues reported.
The problem: this was not a formal study. The patients were treated in various ways in hospitals around the country as part of a food and medicine management program, designed to speed up access to the experimental therapy. That so-called “extended access” program follows what happens to the recipients, but it can not prove the plasma – and not other care they received – was the real reason for improvement.
Rigorous studies around the country have been designed to provide this evidence, by comparing similar patients randomly assigned to receive plasma as a dumb infusion in addition to regular care. But those studies are difficult to complete as the virus grows and grows in different cities. Some patients have also requested plasma instead of agreeing to a study that could give them a place.
“For 102 years we have been discussing whether or not convalescent plasma works,” said Dr. Mila Ortigoza of New York University, referring to the use of plasma in the 1918 pandemic. This time, “we have really undisputed evidence. necessary. “
Ortigoza is co-leading one such study, which this week expands to three other states – Connecticut, Florida and Texas. Her team is also working on pool data with several other clinical trials in other regions, hoping for faster responses.
“There is concern about when there will be a clear answer,” said infectious disease specialist Dr. Jeffrey Henderson of Washington University in St. Louis. Louis.
He hopes the clinical trials will push forward, but said the Mayo report is consistent with smaller, earlier plasma studies and “an example of making the best you can from the available data.”
When the body encounters a new germ, it makes proteins called antibodies that are specifically targeted to fight this particular infection. The antibodies flow into plasma – the yellowish, liquid part of blood. Because it takes a few weeks for antibodies to form, the hope is that transferring antibodies from someone else can help patients fight the virus before kicking in their own immune system.
Mayo’s findings were posted online prior to scientific peer review. They show that 20% of people who received high-antibody plasma within three days of being diagnosed died within 30 days compared to 30% of people who were later treated with low-antibody plasma.
The FDA has closely examined whether the evidence is good enough to allow the so-called emergency use of convalescent plasma, a step that would make it even harder to complete more stringent tests. The FDA did not immediately comment Friday.
Tens of thousands of COVID-19 survivors have donated their plasma, and blood banks have issued calls to further meet the demand as the coronavirus continues to destroy the US According to AABB, the American Association of Blood Banks, a quarter of hospitals the weekly inspections report waiting times of more than 24 hours upon receipt of requested plasma.
Unless plasma in general helps, scientists want to know when to use it – for the very sick or at the first sign of infection? And what is the right dose? The survivors of COVID-19 have widely varying amounts of antibodies, which Ortigoza said is difficult to measure before the donated plasma is used. She said another question is which of the many types of antibodies are the best to use.
Joyner notes that the extended access program was not intended to replace rigorous studies, but was originally designed to track 5,000 people and see if plasma was safe. Instead, the program skyrocketed.
“There is probably reasonable, active evidence from our findings to really confirm” historical lessons of plasma therapy, which earlier use is better, “he said.
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