Peer-reviewed article
Real-World Safety of Concurrent Measles-Mumps-Rubella and Varicella Vaccination in Korean Infants: A Multicenter Self-Controlled Case Series Study.
Sujin Choi, Bin Ahn, Yeonjoo Lee, Gwanglok Kim, Young June Choe et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study evaluated the safety of giving measles-mumps-rubella and varicella vaccines together to Korean infants aged 12-23 months. Researchers tracked adverse events in 3,035 children using health records and found that fever peaked 7-13 days after vaccination but was expected and temporary. No serious safety concerns were identified, and febrile convulsions were rare, supporting the safety of this vaccination approach.
Key points
- Fever was the most common adverse event after concurrent MMR and varicella vaccination, with a 4.27-fold increase during days 7-13 post-vaccination
- Risks of sick visits and acute care visits were elevated only during days 7-13 and returned to baseline afterward
- Febrile convulsions occurred rarely (aRR 5.37), with no serious or sustained safety signals identified
- 71.7% of children received the MAV/06 varicella strain, and no synergistic effects of multi-vaccine administration were detected
- No excess risks were observed during hepatitis A vaccine administration or overlapping periods
Limitations
The study was conducted in South Korea with specific vaccine strains (MAV/06 and Oka-derived) and may not generalize to other populations or vaccine preparations. The findings are limited to infants aged 12-23 months and do not address long-term safety outcomes beyond the immediate post-vaccination period.
Abstract
BACKGROUND: Measles, mumps, rubella (MMR) and varicella vaccines are often co-administered to optimize coverage, yet safety concerns regarding febrile convulsions persist. In South Korea, MMR and varicella vaccines are administered as separate injections during a single visit (MMR + V). This study evaluated the real-world safety of concurrent MMR + V vaccination, focusing on the domestically implemented MAV/06 and Oka-derived strains. METHODS: We conducted a multicenter self-controlled case series (SCCS) study of children aged 12-23 months who received MMR + V and hepatitis A vaccine (HAV) between 2015 and 2024. Using electronic health records, we identified predefined adverse events (AEs), including fever and healthcare visits. Adjusted relative risks (aRRs) were estimated using conditional Poisson regression. RESULTS: Among 3035 children (52.3% male; median age, 12 months), 71.7% received the MAV/06 varicella strain. A distinct peak in AEs occurred 7-13 days after MMR + V administration, with fever showing the greatest increase (aRR, 4.27; 95% CI, 2.76-6.60). The risks of total sick visits (aRR, 2.15; 95% CI, 1.70-2.71) and acute care visits (aRR, 2.13; 95% CI, 1.46-3.10) were similarly confined to this interval and returned to baseline thereafter. Febrile convulsions were uncommon (aRR, 5.37; 95% CI, 1.20-24.01). No excess risks were observed during the HAV or overlap periods, and no synergistic effects of intensive multi-vaccine administration were detected. CONCLUSIONS: Concurrent administration of MMR and varicella vaccines in Korean infants-predominantly using the MAV/06 strain-was associated only with expected, transient increases in fever during days 7-13 postvaccination. No serious or sustained safety signals were identified, supporting the continued use of Korea's separate-injection MMR + V strategy.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Concurrent administration of separate MMR and varicella vaccine injections during a single visit to infants aged 12-23 months
- Population
- 3,035 Korean infants aged 12-23 months (52.3% male; median age 12 months) who received MMR + V and hepatitis A vaccines between 2015 and 2024
Key finding
Fever was the most common adverse event with adjusted relative risk of 4.27 (95% CI 2.76-6.60) during days 7-13 post-vaccination
Choi et al. · PubMed (US National Library of Medicine) · 24 Jun 2026