Filenews 13 November 2021
A Canadian study showed that among people who contracted COVID-19, those aged 50 and over produced more and more effective antibodies compared to younger people – the study also showed that vaccination beats signs in relation to physical disease in terms of the production of antibodies effective against the Delta strain
A research team of different Canadian centres led by two professors in the Department of Chemistry at the University of Montreal set out to answer one of the biggest pandemic questions: does physical infection with the novel coronavirus, or does vaccination against it, lead to the production of more protective antibodies?
Victory against state vaccination and against delta
The extremely interesting answer given by the researchers was published in the journal "Scientific Reports". According to it, people who received the Pfizer/BioNTech vaccine or that of AstraZeneca had levels of antibodies significantly higher than those infected with SARS-CoV-2. It is even noteworthy that the antibodies produced after vaccination appeared to be effective against the highly contagious and dangerous delta strain of the virus that currently dominates in many countries of the world (to emphasize at this point that this strain had not appeared in Quebec, Canada where the samples were collected in 2020).
The mild patients under the "microscope"
The researchers also focused in their study on a group that had not been adequately studied to date: these are people who had been infected with the novel coronavirus but had not needed hospitalization. Thus, they collected samples, from 32 COVID-19-positive adults – all patients had attended the Hospital Center of Laval University – 14 to 21 days after their positive diagnosis, through a molecular test.
The age... Counts
Based on the findings "all people infected with the novel coronavirus had antibodies, but older people produced more antibodies than adults under 50," said Jean-François Masson, a professor in the Department of Chemistry at the University of Montreal and an expert in biomedical tools, and added: "In fact, antibodies were still present in the bloodstream 16 weeks after diagnosis."
The antibodies produced after infection by the "maternal" strain of the virus appeared to react to the strains that appeared in the subsequent pandemic waves, namely beta (South African), Delta (Indian) and Gamma (Brazilian) but at a lower level: the decrease in their effectiveness was in the range of 30%-50%.
Greater degree of protection in... larger
"However, the finding that surprised us the most was that the antibodies produced by people 50 years of age and older who became ill naturally provided a greater degree of protection compared to those of adults under the age of 50," noted the study's other study leader Joel Peletier, also a professor of Chemistry at the University of Montreal, an expert in protein chemistry. "This was determined by measuring the ability of antibodies to inhibit the interaction of the spike protein (protein S) of the SARS-CoV-2 Delta strain with the ACE-2 receptor of human cells–through this interaction humans are infected," the professor added. "We didn't notice the same phenomenon when it came to the other strains of the virus we studied," Dr. Peletier said.
Disease and vaccination: The best combination
In addition, the researchers saw that when a person who had mildly contracted COVID-19 was vaccinated, the levels of antibodies in their blood doubled compared to an unvaccinated person who had also contracted the novel coronavirus disease. In fact, the antibodies of the diseased and then vaccinated person were more effective in preventing the interaction between the spike protein of the virus and the ACE-2 receptor.
"But what was even more interesting was the example of a volunteer under the age of 49 who after a natural infection did not produce antibodies that prevented the interaction of the S protein with the ACE-2 receptor – which was not the case with vaccination. This testifies that vaccination increases protection against the Delta strain in people who were previously infected with the maternal strain of the virus," Dr. Mason said.
Both study leaders believe that further research is needed to determine the combination that will maintain the best and most efficient level of antibodies against all strains of SARS-CoV-2.
