Sero-Epidemiologic Study of Respiratory Syncytial Virus Infection in Korea

Despite the recent introduction of a respiratory syncytial virus (RSV) vaccine, there is no sero-epidemiologic study of RSV infection among old adults in Korea. This study aimed to assess humoral immune responses to RSV among different age groups in Korea.

A total of 400 serum samples (100 samples from each of the following age groups: 10-20, 21-40, 41-60, and 61-80 years) were selected randomly from a general population cohort used for health status evaluation in Korea (the Korea National Health and Nutrition Examination Survey 2019-2020 cohort). Anti-RSV IgM and IgG levels, along with total IgM and IgG levels, were measured in enzyme-linked immunosorbent assays.

Anti-RSV IgM levels were higher in individuals aged 10-20 and 21-40 years than in the other age groups (121.43 U/mL vs. 102.33 U/mL vs. 76.71 U/mL vs. 64.89 U/mL, P < 0.05), whereas anti-RSV IgG levels were similar across all age groups. Although the proportion of anti-RSV IgM relative to total IgM, respectively, was higher in the 10-20 age group than in the other groups (16.05% vs. 13.26% vs. 10.95% vs. 11.06%, P < 0.001), there was no significant difference among the 21-40, 41-60, and 61-80 age groups. Finally, there was no significant difference in anti-RSV IgG positivity rate among the age groups; however, the rate of anti-RSV IgM positivity was higher in the groups aged 10-20 and 21-40 years (73% vs. 54% vs. 28% vs. 28%, P < 0.001).

RSV infections are recurrent in people over the age of 40 in Korea, but at a lower rate than in those aged 10-40. Therefore, more attention should be paid to RSV infections in the adult population in Korea.