Impact of social distancing on incidence of vaccine-preventable diseases, South Korea.

While vaccination remains the cornerstone of controlling vaccine-preventive diseases (VPD), little is known about the effect of social distancing on incidence of VPDs. We investigated the impact of social distancing practiced during the coronavirus disease 2019 (COVID-19) pandemic on the incidence of selected VPDs in South Korea. National surveillance data on monthly incidence of hepatitis A, hepatitis B, varicella, mumps, invasive pneumococcal disease (IPD), and pertussis were retrieved and compared the VPD incidences in 2020 to the average of the last 4 years (2015-2019) of the corresponding months. In 2020, there were 44% decline for mumps, 44% decline for varicella, 28% decline for pertussis, 22% decline for IPD, 14% decline in incidence of hepatitis A, and no change for hepatitis B incidences, compared to baseline years (2015-2019). The largest decline of total VPDs was in April (65%) and in May (67%), during the intensified social distancing measures. In the setting of sustained vaccination coverage, social distancing may provide additional public health benefit in controlling the VPDs.