Abstract

BACKGROUND

Annual vaccination for influenza is globally recommended for some prioritized groups due to its high morbidity and mortality. Until 2019, South Korea has provided free influenza vaccination to children aged ≤12, adults aged ≥65, and pregnant women to enhance vaccination coverage. In 2020, with the COVID-19 pandemic, free flu vaccination was temporarily broadened to adults aged 62-64 and children aged 13-18. We analyzed the trends in influenza vaccination coverages in South Korea and evaluated the impact of the COVID-19 pandemic and the expansion of the free vaccination policy on influenza vaccination coverage.

METHODS

We conducted a cross-sectional study with nationwide survey data from Korea National Health and Nutrition Examination Survey (KNHANES). We evaluated the trends in influenza vaccination coverages of target populations from 2010 to 2020. Influenza vaccination coverages of children aged 13-18, adults aged 62-64, and adults aged ≥65 were compared between 2019 and 2020.

RESULTS

In total, 72,443 individuals were analyzed. From 2019 to 2020, with the expansion of free influenza vaccination and the COVID-19 pandemic, the vaccination coverage of children aged 13-18 increased from 27.8% to 43.5% (P<0.001) but that of people aged 62-64 showed insignificant change from 57.4% to 51.5% (P = 0.266). Furthermore, the vaccination coverage in adults aged ≥65 declined from 87.2% to 79.1% (P<0.001).

CONCLUSION

In 2020, along with COVID-19 outbreaks, a decline of influenza vaccination coverage in older adults was observed regardless of free immunizations. It is likely due to behavioral changes to reduce the risk of COVID-19 transmission. This is supported by a greater reduction of influenza vaccination coverage in regions with higher COVID-19 outbreaks, as well as by South Korea's high medical accessibility and highly congested medical facilities. To sustain a high level of vaccination coverage of high-risk population during epidemics, additional efforts beyond free vaccination policies should be implemented.

MeSH

Disease Outbreaks, Vaccines, Vaccination, Aged, Covid-19, Influenza, Human, Pandemics, Vaccination Coverage, Child

Cited by

• Association Between Sociodemographic Factors and Vaccine Acceptance for Influenza and SARS-CoV-2 in South Korea: Nationwide Cross-Sectional Study. JMIR Public Health Surveill, 2024
• Disentangling behavioral determinants of seasonal influenza vaccination in post-corona era: An integrated model approach. PLoS One, 2025
• Vaccine uptake, associated factors and reasons for vaccination status among the South African elderly; findings and next steps. PLoS One, 2024
• Analysis of the incidence of influenza before and after the COVID-19 pandemic in South Korea. Trop Med Int Health, 2024
• Socioeconomic disparities in influenza vaccination uptake: impact of the COVID-19 pandemic in South Korea. BMC Public Health, 2025
• The impact of the COVID-19 pandemic and the free vaccination policy on seasonal influenza vaccination uptake among older adults in Ningbo, Eastern China. Hum Vaccin Immunother, 2024