A clinical study conducted in Argentina in 160 elderly people showed that it is possible to avoid severe symptoms of Covid-19 with treatment based on plasma rich in antibodies to the new coronavirus.
This plasma was obtained from donations from people who already had Covid-19 and who were already asymptomatic and had a negative test for the presence of the virus. Each donation (which can be repeated every two weeks) removed 750 ml of plasma, enough to treat three patients.
The volunteers had a mean age of 77.2 years and were randomly split between the test groups (who received the plasma) and the placebo groups (who received saline only). To participate in the study, it was required to be 75 years of age or older, or between 65 and 74 years of age, and to have some comorbidities such as diabetes, high blood pressure, obesity, and chronic kidney disease.
The study was a double-blind study in which neither scientists nor participants knew who was receiving each treatment, reducing the chance of interpretation bias.
According to Fernando Polack, a doctor specializing in pediatric infectious diseases who led the study, the result suggests that with hundreds of thousands of potential donors who already had the disease, it would be possible to calm the most vulnerable populations like the elderly and the elderly to care for those with comorbidities. The infusion can be carried out on an outpatient basis and takes less than 1 hour 30.
So far, studies based on so-called convalescence plasma have not shown any great effectiveness against Covid-19. The explanation for this, says Polack, is that the therapy only works well in the first few days of the infection.
The study only recruited patients with symptoms that began less than 72 hours, ie even in the first week of infection, taking into account the incubation period.
“Treatments for infectious respiratory diseases usually work best when given beforehand, as in the case of Tamiflu for influenza. It is possible to contain progress, but it has to be quick. In our study, we prevent one serious case from four people treated. Hence, one needs to focus on those who are most at risk. “
The result was a 48% reduction in the risk of developing severe respiratory disease (e.g., breathing quickly and having low levels of oxygen in the blood). There were no side effects of the treatment.
When the plasma was particularly rich in antibodies, which usually occurs after severe infections that lead the individual to hospitalization, the protection was even greater, reaching 73%.
Probably due to the small sample size (160 people, not thousands), other results, such as the reduction in deaths (there were 2 in the test group and 4 in the placebo), did not show what is known as statistical significance, if one can say: with a good level of Trust that an effect has a well-founded reason.
The lack of evidence to reduce deaths means that this strategy is still not attracting as much interest, points out Alexandre Barbosa, head of Infectious Diseases Sector at Unesp and advisor to the Brazilian Society of Infectious Diseases.
“It’s promising work that has shown the potential to prevent disease progression in high risk patients, but this is not the definitive answer for including treatment. It would be necessary to observe a decrease in deaths which, due to the small sample size, likely was not. “
Increasing the sample size would not be possible from a logistical or even ethical point of view, argue the authors, since it would take much longer to recruit the total number of patients in the study and the possible benefits of this therapy would remain unknown for much longer.
“It’s a small study, but when we look at the secondary findings like oxygen supplement need, intubation, ICU admission and death, they all point in the same direction. We knew that it would not be possible to statistically identify these differences, but it is possible, based on what we saw, to assume that there will be fewer hospitalizations and fewer deaths in less severe cases, ”says Polack.
The results of the study conducted by the Argentine Infant Foundation were published this Wednesday (6) in the prestigious journal The New England Journal of Medicine.
With a low cost of less than R $ 1,000 per patient compared to other interventions, plasma can act as a “bridge” to universal vaccination, argues Polack, who was also the first author on the safety and efficacy study of the Pfizer vaccine.
Even the first people to be vaccinated could participate in the donation of antibodies as immunizers tend to produce large numbers of them in the body. It would be a way to share the benefits of the privilege of vaccination.
“Effective alternatives that can be quickly made available to prevent patients with Covid-19 from being hospitalized are essential to save lives as new vaccines take time to reach those in need,” says Keith Klugman, Director of the Pneumonia Program at the Bill Foundation & Melinda Gates, lead sponsor of the study, in a press release.
The challenge remains to come up with proposals to governments, regulators, healthcare providers and insurers, highlight these benefits and try to implement them within the regulatory specifics of each country. This process can take weeks or months.
Compared to other treatment suggestions for Covid-19 such as hydroxychloroquine and nitazoxanide, the Argentine doctor says the scientific strength of the plasma is greater and is confirmed by the placebo-controlled double-blind study and publication in a good scientific journal with peer review such as NEJM.
“Some scientists have announced results with very weak or nonexistent evidence to get media attention, and many decisions have been guided by fear, not data. In our study we show this potential very clearly, ”says Polack.
Plasma therapy reduces the severity of Covid-19
Find out if plasma donated by people who have already been infected with the new coronavirus can reduce the severity of the disease in infected elderly patients
160 infected elderly patients were recruited and showed symptoms within 72 hours of treatment – 80 for the test group that received plasma high in antibodies to Sars-CoV-2-80 that they received for the placebo group that received it Saline solution
Patients who received plasma were 48% less likely to develop severe respiratory disease
The scientists also found that the more concentrated and effective the antibodies, the better the plasma therapy performance
Argentinian researchers believe this can be an important treatment alternative to prevent serious illness and, consequently, hospitalization and death. The cost is US $ 186.25 (R $ 977.51) per patient
Source: The New England Journal of Medicine