Changes in SARS-CoV-2 antibody titers after COVID-19 vaccination

In a recent study posted on medrex sib* In a preprint server, researchers are evaluating changes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) antibody titers over time following SARS-CoV-2 vaccination .

study: Time course of IgG-type SARS-CoV-2 antibody titers after COVID-19 vaccination and significant increase in antibody titers when infected after vaccination. Image credit: alphaspirit.it / Shutterstock.com

COVID-19 vaccination and antibody production

The range and duration of SARS-CoV-2 antibody titers are considered important indicators of the efficacy of 2019 novel coronavirus disease (COVID-19) vaccines. However, several studies have confirmed that SARS-CoV-2 titers decline months after vaccination.

In 2022, Japan experienced a sixth wave of COVID-19 cases. This was primarily caused by the rapid spread of the SARS-CoV-2 Omicron strain. In fact, the number of patients who reported infection after the sixth wave was much higher than the total number of patients before the sixth wave. Therefore, we can speculate that breakthrough transmission of COVID-19 after two or more vaccinations is prevalent. However, only a few studies have studied SARS-CoV-2 antibody titers over time after natural infection and vaccination.

About research

In this study, researchers will investigate changes in antibody titers after the second and third doses of the SARS-CoV-2 vaccine to determine antibody titers in natural infections with COVID-19 after vaccination .

This longitudinal observational study included recruitment of both outpatients and health care personnel. Between June 2021 and February 2023, a total of 127 participants, including 74 outpatients and her 53 medical staff, tested SARS-CoV-2 and receptor binding domain (RBD) A serum sample was submitted for evaluation of IgG antibody titers.

Associations between antibody titers, age of participants, and time interval after second vaccination in 56 participants with no known history of SARS-CoV-2 infection and known vaccination dates Rated. The same assessment was performed on 23 participants with a history of COVID-19 and accurate vaccination dates after the third vaccination.

The association of pre- and post-vaccination antibody titers was assessed in 13 individuals whose titers were measured before and after the third vaccination. Post-infection antibody titers were also evaluated in patients who received two or more doses of COVID-19 vaccination.

Investigation result

Antibody titers were assessed in 56 participants who received the second vaccination.At that time antibody titer No history of COVID-19 was reported in these participants at evaluation.

The average antibody titer was approximately 4,807 AU/mL, with a decreasing trend. Furthermore, the correlation between antibody titers and the time interval after the second vaccination was negative. A weak, non-significant association between antibody titers and age was also observed.

Eight patients whose antibody titers were assessed several times after receiving the second dose of vaccine showed long-term changes in antibody levels over time. Initial antibody titers were estimated within 1 month after the second vaccination. However, titers varied greatly from person to person.

By 3 months, antibody titers had dropped by half to a third. By 6 months, antibody titers had dropped to several hundred AU/mL.

Before receiving the third dose of vaccine, these eight patients had significantly reduced antibody titers. Dividing the difference between the minimum and maximum titers by the period between her two serum samples, the researchers observed that the higher the maximum, the faster the antibody titers declined each day.

Antibody titers were assessed in 23 patients after the third dose of vaccine. The mean antibody titer at this time point was 12,617 AU/mL, significantly higher than after the second vaccination.

The time interval between the third vaccination and antibody titer measurement was negatively correlated with antibody titers, but a negative correlation was also observed between the time interval and titers after the second vaccination. I was. As with the second vaccination, there may be a small association between age and vaccine Effectivenesshowever, this was not statistically significant.

Conclusion

The increase in anti-SARS-CoV-2 antibody titers and the duration for which effective levels are maintained were thought to be an accurate indicator of the effectiveness of new COVID-19 vaccines.

Rather than indiscriminately prescribing booster immunizations to the population as a whole, researchers believe it is preferable to assess antibody titers and prioritize individuals with low titers for booster vaccination. Nonetheless, future longitudinal studies of antibody titers on a broader scale are needed.

*Important Notices

medrex sib We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.