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Real-World Safety of Concurrent Measles-Mumps-Rubella and Varicella Vaccination in Korean Infants: A Multicenter

Sujin Choi1, Bin Ahn2,3, Yeonjoo Lee4

  • 1Department of Pediatrics, Konkuk University Medical Center, Seoul 05030, Republic of Korea.

Vaccines
|July 27, 2026
PubMed

Insights

Concurrent measles, mumps, rubella (MMR) and varicella vaccination in Korean infants showed a transient increase in fever 7-13 days post-vaccination. This real-world safety data supports the continued use of separate MMR + V injections.

Area of Science:

  • Pediatrics
  • Immunology
  • Public Health

Background:

  • Co-administration of Measles, Mumps, Rubella (MMR) and varicella vaccines is common for optimal coverage.
  • Safety concerns, particularly febrile convulsions, persist with combined vaccination strategies.
  • South Korea utilizes a separate-injection approach for MMR and varicella vaccines (MMR + V) during a single visit.

Purpose of the Study:

  • To evaluate the real-world safety of concurrent MMR + V vaccination in Korean infants.
  • To assess adverse events, specifically fever and febrile convulsions, following MMR + V administration.
  • To analyze the safety profile of domestically implemented MAV/06 and Oka-derived varicella vaccine strains.

Main Methods:

  • A multicenter self-controlled case series (SCCS) study was conducted.
  • Included children aged 12-23 months who received MMR + V and hepatitis A vaccine (HAV) between 2015 and 2024.
  • Electronic health records were used to identify adverse events, with adjusted relative risks estimated via conditional Poisson regression.

Main Results:

  • A peak in adverse events, primarily fever (aRR, 4.27), occurred 7-13 days post-MMR + V.
  • Increased risks of sick visits (aRR, 2.15) and acute care visits (aRR, 2.13) were confined to this period.
  • Febrile convulsions were uncommon (aRR, 5.37), with no excess risks during HAV or overlap periods.

Conclusions:

  • Concurrent MMR + V vaccination in Korean infants, predominantly using the MAV/06 strain, resulted in expected, transient fever increases.
  • No serious or sustained safety signals were identified.
  • The findings support the continued use of Korea's separate-injection MMR + V strategy.
Abstract

Keywords:
measles-mumps-rubella vaccinevaccine safetyvaricella vaccine

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