High Levels of Anti-SARS-CoV-2 Receptor-Binding Domain (RBD) Antibodies One Year Post Booster Vaccinations among Hospital Workers in Indonesia: Was the Second Booster Needed?

• Published in: Vaccines (Basel) Vol. 11; no. 8; p. 1300
• Main Authors: Muslimah, Amila Hanifan, Tiara, Marita Restie, Djauhari, Hofiya, Dewantara, Muhammad Hafizh, Susandi, Evan, Indrati, Agnes Rengga, Alisjahbana, Bachti, Soeroto, Arto Yuwono, Wisaksana, Rudi
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 30.07.2023; MDPI
• Subjects: Antibodies; antibody; Brief Report; Care and treatment; Comorbidity; Control; COVID-19 vaccination; COVID-19 vaccines; Diagnosis; Disease transmission; Epidemics; Family physicians; Health aspects; Health care; healthcare worker; Hospitals; Illnesses; Immunization; Indonesia; Infections; Medical personnel; Risk groups; Serological tests; Severe acute respiratory syndrome coronavirus 2; Social aspects; Software; Vaccines; Indonesia
• ISSN: 2076-393X; 2076-393X
• DOI: 10.3390/vaccines11081300

In August 2022, Indonesia prioritized healthcare workers to receive the second booster dose. We conducted a sequential serosurvey to understand the dynamics of the antibody titers. The first serosurvey, which was conducted in June 2021, 1–6 months after Sinovac vaccination, showed a median antibody level of 41.4 BAU/mL (interquartile range (IQR): 10–629.4 BAU/mL). The second serosurvey was conducted one month (August 2021) after the first Moderna booster vaccine and showed a median level of 4000 BAU/mL (IQR: 3081–4000 BAU/mL). The last serosurvey was conducted a year (August 2022) after the booster and showed a median level of 4000 BAU/mL (IQR: 4000–4000 BAU/mL). In this last survey, only 39 (11.9%) of healthcare workers had antibody levels below the maximum level of 4000 BAU/mL. Thus, one year after the first booster dose, we did not observe the waning of antibody levels. The average increase was perhaps because of natural infection. Based on these considerations, we believe that a second booster dose was not necessary for this category of subjects at that time. Because vaccine supply is often limited, priority could be given to the general population or other high-risk patient groups with low antibody titers based on serological tests.