Seroprevalence of SARS-CoV-2 anti-nucleocapsid total Ig, anti-RBD IgG antibodies, and infection in Thailand: a cross-sectional survey from October 2022 to January 2023

Abstract

Seroprevalence studies on SARS-CoV-2 are essential for estimating actual prevalence rates of infection and vaccination in communities. This study evaluated infection rates based on total anti-nucleocapsid immunoglobulin (N) and/or infection history. We determined the seroprevalence of anti-receptor binding domain (RBD) antibodies across age groups. A cross-sectional study was conducted in Chonburi province, Thailand, between October 2022 and January 2023. Participants included newborns to adults aged up to 80 years. All serum samples were tested for anti-N total Ig and anti-RBD IgG. The interviewer-administered questionnaires queried information on infection history and vaccination records. Of 1459 participants enrolled from the Chonburi population, ~ 72.4% were infected. The number of infections was higher in children aged < 5 years, with evidence of SARS-CoV-2 infection decreasing significantly with increasing age. There were no significant differences based on sex or occupation. Overall, ~ 97.4% of participants had an immune response against SARS-CoV-2. The anti-RBD IgG seroprevalence rate was lower in younger vaccinated individuals and was slightly increased to 100% seropositivity at ages > 60 years. Our findings will help predict the exact number of infections and the seroprevalence of SARS-CoV-2 in the Thai population. Furthermore, this information is essential for public health decision-making and the development of vaccination strategies.

Real-World Study: Hybrid Immunity against SARS-CoV-2 Influences the Antibody Levels and Persistency Lasting More than One Year

“…In this study, a comparison between HCW and NHCW did not reveal any statistically significant differences across the observed durations, including periods over a year. This contrasted with a prior study conducted from October 2022 to January 2023, which showed higher anti-RBD IgG levels among HCWs compared to the general population [16]. This study suggests that occupation may not significantly affect total anti-RBD Ig levels.…”

“…Among the 771 individuals, 71.7% were classified as N pos , which substantially exceeded those identified by records of infection history (58.7%). The results demonstrated that the seroprevalence of COVID-19 in Bangkok observed between April and June 2023, was close to that of the previous serosurvey conducted between October 2022 and January 2023 in Chonburi province (accounting for 73.7% of 1076 out of 1459 individuals) [16]. We anticipated that the infection rate would further rise throughout the entire population of Thailand.…”

Seroprevalence of measles and varicella in healthcare workers in Chonburi province, Thailand between October 2022 and January 2023

“…This cross-sectional study was part of the large-scale serosurvey conducted in 11 districts in Chonburi province, Thailand, between October 2022 and January 2023 [20]. In the large-scale serosurvey, there was a total of 1193 general population and 266 HCWs.…”