Study: Almost 80% of the vaccinated have protective antibodies against severe forms of COVID-19, even 6 months after the booster

The third dose of vaccine becomes a priority for men over 50 with diabetes, obesity, cancer or cardiovascular disease and no history of COVID, a MedLife study says.

Specialists from the MedLife research division announced the final results of the third stage of the study that assesses the body’s immune response to vaccination against COVID-19, 6 months after the booster. In order to follow the dynamic evolution of the anti-S antibody titre, the approach involved the collection of biological samples in order to detect anti-Spike (anti-S) and anti-Nucleocaspida (anti-N) IgG antibodies at 8-15 days, 3 months and, respectively, 6 months after administration of the second dose of vaccine.

The results regarding the SARS-CoV-2 antibody titre, as well as all the correlations identified are representative for the Romanian population segment that was vaccinated with Pfizer BioNTech, as this was the only vaccine available in Romania at the start of the study.

The research revealed that 3 out of 4 vaccinated people have a level of antibodies that could be protective against severe forms of COVID-19 even 6 months after the booster.

The MedLife study shows that although the antibody titre decreases within 6 months of booster administration (the average rate of decrease in anti-S antibodies is 78% on the sample studied – from 1050 AU / ml to 233 AU / ml) 3 of 4 vaccinated individuals have anti-S titre values ​​higher than 80 AU / ml even at 6 months post-vaccine, suggesting some protection against severe forms of COVID-19 in case of exposure to SARS virus -CoV-2.

In fact, the percentage of people who became infected with the SARS-CoV-2 virus in the first 6 months after vaccination is less than 2% of the total sample, most being people over 40 years, who at 8-15 days of booster did not exceed antibody titre values ​​greater than 300 AU / ml.

“The analyzed data show that 78% of vaccinated people have, even 6 months after the booster, a titre of anti-S antibodies that could provide protection against severe forms of the disease. Which is very good news, especially in the context of the Delta strain, which we know is at least twice as contagious and doubles the risk of hospitalization in case of infection, has become responsible for the rapid increase in the number of positive cases from our country in recent days. People need to understand that the only way to protect against serious forms of the disease, which could be caused by this new strain or other mutations in the virus, remains vaccination, in conjunction with compliance with protection measures,” said Dumitru. Jardan, biologist, doctor of medical sciences, MedLife.

Gender, age, history of COVID, but also the presence of comorbidities, influence anti-S antibodies acquired post-vaccine

Data analyzed by MedLife specialists indicate that women have a higher level of anti-S antibodies at 6 months post-booster in a higher proportion than men (85% women vs. 69% men). The high share of women is maintained even with age, while for men age is a risk factor. Thus, just over 50% of men over the age of 50 still have a protective title of anti-S antibodies and at 6 months after booster, while among women in the same age group the percentage of those with a protective title of anti-S antibodies S is over 80%.

The MedLife study also shows that those who have previously been infected and vaccinated after that have a higher level of anti-S antibodies than those who have only been vaccinated. Thus, 94% of the participants in the study with a history of COVID-19 have an anti-S antibody titer greater than or equal to 80AU / ml and 6 months after the administration of the vaccine vs. 72% registered among people who did not go through the disease.

Regarding comorbidities, MedLife doctors point out that their presence interferes with the level of anti-S antibodies, the values ​​of the antibody titer after the administration of the vaccine in patients with chronic diseases being 2-3 lower compared to the average calculated in the whole population.

In fact, the MedLife study shows that only half of those who suffer from at least 2 chronic conditions still have a level of anti-S antibodies that suggest protection against severe forms of COVID-19, while 8 out of 10 people do not have the disease. chronic and 6 months after booster a comparable antibody titer. The most vulnerable are patients over the age of 50, who suffer from diabetes, obesity, oncological diseases, cardiovascular or lung diseases.

People over the age of 50, especially men, who suffer from diabetes, obesity, cancer, cardiovascular or lung disease should be given priority for the third dose of vaccine, the researchers say.

MedLife’s research confirms that the post-vaccination immune response, even 6 months after the booster, varies according to several criteria – age, gender, associated chronic diseases, which is why the differentiated approach to the scheme is justified. vaccination and the priority administration of the third dose of vaccine to categories with identified risk factors.