In a recent Journal of Infection and Chemotherapy study, researchers investigate the dynamics of anti-spike immunoglobulin G (IgG) levels against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) peak protein in Japanese health workers.
Examination: Dynamics of anti-Spike IgG antibody level after the second BNT162b2 COVID-19 vaccination in healthcare professionals. Image credit: Matheus Nunes de Oliveira / Shutterstock.com
The current study was conducted over a period of six months after study participants received the second dose of their coronavirus disease 2019 (COVID-19) vaccine. In addition, the researchers were interested in identifying indicators of the need to prioritize an additional vaccination dose in certain populations.
Messenger ribonucleic acid (mRNA) vaccines for COVID-19, including the merna DNA of the Moderna mRNA-1273 and the Pfizer / BioNTech BNT162b2 vaccine, have been very effective in preventing COVID-19 in the real world. However, there has been a resurgence of COVID-19 cases in many countries, first driven by the SARS-CoV-2 Delta (B.1.617.2) variant and subsequently by the Omicron (B.1.1.529) variant.
In response to this increase in new COVID-19 cases, a third (booster) dose of COVID-19 vaccines has been approved in many countries; however, a thorough evaluation of immunity induced by COVID-19 vaccines has not been performed. Thus, the present study evaluated the levels of anti-spike IgG six months after BNT162b2 vaccination in Japanese health workers.
About the study
The participants in the study consisted of healthcare professionals at Haradoi Hospital in Fukuoka, Japan. Nearly 76% of the 485 health workers at this hospital participated in this study. None of the participants used immunosuppressants and were not affected by COVID-19 during the six-month study period.
While most of the participants were nurses, about 80% were women. All participants gave written informed consent prior to enrolling in the study. The assessments were carried out in accordance with the principles of the Declaration of Helsinki and were approved by the Institutional Ethics Review Committee at Haradoi Hospital prior to data collection.
The study included two sub-studies. In Analysis-1, the researchers assessed the dynamics of anti-spike IgG levels over a period of six months after the second dose of BNT162b2 vaccination in 49 study participants. Assay-2 assessed cross-sectional anti-spike IgG levels six months after the second dose of BNT162b2 vaccination in 373 participants.
Anti-spike IgG levels were measured by the SARS-CoV-2 IgG II Quant assay. Analysis-1 participants underwent blood tests six times for the quantitative assessment of anti-spike IgG, while Analysis-2 participants underwent blood tests to determine anti-spike IgG levels in October 2021 six months after receiving the second vaccine dose .
Assay-1 participants also underwent blood tests to assess their levels of aspartate aminotransferase (AST), total bilirubin, alanine aminotransferase (ALT), serum creatinine, and γ-glutamyl transpeptidase (γ-GTP) using standard enzymatic assay methods.
The median age of the participants was about 40 years, whereas the median interval between the second vaccination date and the blood collection date in Analysis-2 was 185 days. Anti-spike IgG geometric mean titers were lower in the older population in Assay-1, which lasted for six months after second vaccination.
Anti-spike IgG levels peaked one month after the second vaccination. The geometric mean IgG levels were 13,883 AU / ml in the age group 20-30 years, while they were 10,736 AU / ml in the 40-50 age group and 5,887 AU / ml in the age group over 60 years.
Anti-spike IgG geometric mean titers decreased consistently after the second vaccine dose, regardless of age, with a decrease of approx. 90% from one to six months after the second dose. The geometric mean IgG levels six months after receiving the second dose of vaccine were 1,044 AU / ml in the age group of 20-30 years, 770 AU / ml in the age group of 40-50 years and 464 AU / ml in those over 60 years. age group.
In Assay-2, anti-spike IgG levels had significant negative associations with age. This association was statistically significant, even after adjusting for factors such as body mass index (BMI), gender, smoking habits, allergies, drinking habits and fever or other side effects during vaccination.
The team performed logistic regression analyzes to determine the factors that contributed to anti-spike IgG levels above 2,150 AU / ml six months after vaccination. In univariate analyzes, fever after vaccination and age were the main factors influencing anti-spike IgGs above 2,150 AU / ml, whereas drinking habits and age were influencing factors in multivariate analyzes.
In fact, study participants who consumed alcohol each day had significantly reduced anti-spike IgG levels compared to those who had never consumed alcohol. None of the 53 participants who consumed alcohol daily had anti-spike IgG levels of 2,150 AU / ml or more. Factors such as sex, allergies, smoking habits, fever or other side effects after vaccination were not significantly associated with anti-spike IgG levels.
The results of the study show that six months after vaccination, anti-spike IgG levels were significantly lower in the elderly and those who drank alcohol daily. This may indicate the need for an additional dose of the COVID-19 vaccine for these risk groups.
- Ikezaki, H., Nomura, H., & Shimono, N. (2022). Dynamics of anti-Spike IgG antibody level after the second BNT162b2 COVID-19 vaccination in healthcare professionals. Journal of Infection and Chemotherapy. doi: 10.1016 / j.jiac.2022.02.024.