J Korean Med Sci.  2021 Sep;36(36):e222. 10.3346/jkms.2021.36.e222.

Waning Effectiveness of One-dose Universal Varicella Vaccination in Korea, 2011–2018: a Propensity Score Matched National Population Cohort

  • 1Department of Preventive Medicine, Korea University College of Medicine, Seoul, Korea
  • 2Department of Pediatrics, Korea University Anam Hospital, Seoul, Korea
  • 3Department of Pediatrics, Incheon Sejong Hospital, Incheon, Korea
  • 4Department of Pediatrics, Chungbuk National University Hospital, Cheongju, Korea
  • 5Department of Pediatrics, Seoul Metropolitan Government - Seoul National University Boramae Medical Center, Seoul, Korea
  • 6Department of Pediatrics, Seoul National University Hospital, Seoul, Korea
  • 7Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea


Despite high coverage (~98%) of universal varicella vaccination (UVV) in the Republic of Korea since 2005, reduction in the incidence rate of varicella is not obvious. The study aimed to evaluate the vaccine effectiveness (VE) of one-dose UVV by timeline and severity of the disease.
All children born in Korea in 2011 were included for this retrospective cohort study that analyzed insurance claims data from 2011–2018 and the varicella vaccination records in the immunization registry. Adjusted hazard ratios by Cox proportional hazard models were used to estimate the VE through propensity score matching by the month of birth, sex, healthcare utilization rate, and region.
Of the total 421,070 newborns in the 2011 birth cohort, 13,360 were matched for age, sex, healthcare utilization rate, and region by the propensity score matching method. A total of 55,940 (13.29%) children were diagnosed with varicella, with the incidence rate 24.2 per 1000 person-year; 13.4% of vaccinated children and 10.4% of unvaccinated children. The VE of one-dose UVV against any varicella was 86.1% (95% confidence interval [CI], 81.4–89.5) during the first year after vaccination and 49.9% (95% CI, 43.3–55.7) during the 6-year followup period since vaccination, resulting in a 7.2% annual decrease of VE. The overall VE for severe varicella was 66.3%. The VE of two-dose compared to one-dose was 73.4% (95% CI, 72.2–74.6).
We found lower long-term VE in one-dose vaccination and waning of effectiveness over time. Longer follow ups of the vaccinated children as well as appropriately designed studies are needed to establish the optimal strategy in preventing varicella in Korea.


Chickenpox Vaccine; Immunity; Heterologous; Varicella Zoster Virus Infection; Cohort Studies; Vaccine
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