Regina Maria study: COVID-19 vaccines still highly effective three months after the first dose

A study by Romanian private medical services provider Regina Maria found that COVID-19 vaccines are still highly effective three months after the first dose, although the level of vaccine-induced antibodies drops, on average, by 66%.

Regina Maria announced on May 26 the results of the second phase of its study evaluating the immune response after vaccination. This stage continues the research launched in January 2021, which assessed the dynamics of post-vaccination antibodies to estimate the level of protection provided by the COVID-19 vaccine.

After the start of the first vaccination phase in Romania, Regina Maria enrolled in this study a sample of 395 people vaccinated with Pfizer. The second stage of the research looks at the levels of antibodies three months after the first dose.

“At this stage of the study, we wanted to analyze how the antibody titer evolved three months after the start of the vaccination scheme, and, especially, how the human body responds to the virus. Our findings are encouraging because we note that, although there is a decrease in the number of antibodies, the effectiveness of vaccines remains high,” said doctor Andreea Alexandru.

According to data collected in the Regina Maria study, a decrease in the levels of vaccine-induced antibodies was observed three months after the first dose. However, the medical services provider says this is normal and does not affect the effectiveness of vaccines. On average, antibody levels dropped by 66%.

The same study found that those who have recovered from COVID-19 infection and received a vaccine still had a higher level of antibodies than vaccinated people who had not been previously infected.

Out of the total of 395 people tested, 33 (8%) also experienced increases in antibody levels compared to the first test.

“We paid special attention to the 33 people who recorded increases in antibody levels. They were all tested additionally for IgG anti-Nucleocapsid antibodies, the COVID-specific antibodies, to see if they were infected. Three of them developed such antibodies, and all were previously confirmed positive by RT-PCR testing,” epidemiologist Teodora Ionescu explained.

Only 1.26% of all vaccinated individuals included in the study tested positive for COVID-19 after vaccination, and all of them (namely five patients) had mild forms who did not require hospitalization. According to Regina Maria, as expected, these patients experienced increases in antibody levels.

The study also revealed an interesting conclusion - overweight individuals recorded relatively higher average antibody values than those of normal weight, both one month and three months after vaccination.