- After passing the SARS-CoV-2 infection, protection against re-infection lasts for a long time, while 6 months after vaccination, the so-called Breakthrough infections are happening more and more often, scientists from the Israeli Sheba Medical Center indicate.
A group of Israeli researchers conducted a study that analyzed the humoral (antibody-based) immune response in unvaccinated people who had been infected with the coronavirus up to a year earlier. Experts compared the results with the resistance of volunteers who were not infected for 8 months and received two doses of Pfizer.
- In both Covid-19 survivors and vaccinated people, the antibody count decreases over time. However, after the infection itself, the antibodies "gain" quality - the authors of the analyzes indicate.
The test persons were infected with alpha and beta strains of the virus. In total, of the 130 volunteers who underwent COVID-19, none re-infected during the study. Moreover, double vaccinated patients also did not get sick, despite the fact that during the same period in Israel, reports of infections began to appear among people vaccinated with two doses, never infected he alth workers. These infections started 6 months after taking the second dose.
Scientists tested the effect of antibodies from 16 unvaccinated convalescents and 22 people who were vaccinated with a double dose and who were never ill. It turned out that a month after vaccination, the number of antibodies in the vaccinated was higher than in the survivors, but it fell more rapidly. Importantly, initially the antibodies worked better in vaccinated patients, but after 6 months, their quality did not change, while those who received the infection showed an improvement in this aspect.
Contrary to expectations, obese convalescents (with a body mass index of 30 and above) had more antibodies than those with a lower BMI (overweight and normal weight). This suggests that obese people may be better protected against future infection than leaner people, the authors of the study indicate.
However, scientists pay attention to the fact that the transmission of the disease is notbest solution. Why? Of all the convalescents, as much as 36 percent. suffered from the symptoms of the so-called long COVID, i.e. u:
- 5 percent psychological deterioration was noted,
- 9 percent neurological problems were found,
- 31 percent respiratory system disorders have been noticed.
- While antibody counts decline in both unvaccinated survivors and vaccinated (but never infected), the quality of antibodies increases after infection, but not after vaccination. Obese people after infection have a clearly stronger, sustained immune response based on antibodies. These results point to specific features of the immune response that could explain the differences in protection against Covid-19 in previously infected persons versus only those who were vaccinated, the researchers concluded.
Detailed results of the research are to be presented during the April European Congress of Clinical Microbiology & Infectious Diseases.