Multisystem inflammatory syndrome in children (MIS-C) cases by vaccination status in California

Area of Science:

• Pediatric infectious diseases
• Vaccinology
• Public health surveillance

Background:

• Multisystem inflammatory syndrome in children (MIS-C) is a rare but serious post-SARS-CoV-2 condition.
• Understanding MIS-C risk factors, including vaccination status, is crucial for pediatric health.
• California's passive disease surveillance system captured MIS-C cases in children under 21.

Purpose of the Study:

• To compare the incidence of MIS-C in vaccinated versus unvaccinated children aged 5-17 years.
• To assess the protective effect of the Pfizer-BioNTech vaccine against MIS-C.
• To analyze MIS-C rates in different pediatric age groups.

Main Methods:

• Retrospective analysis of MIS-C cases reported via California's passive disease surveillance system.
• Comparison of MIS-C incidence rates between unvaccinated and Pfizer-BioNTech vaccinated children (aged 5-11 and 12-17 years).
• Calculation of incident rate ratios (IRR) with 95% confidence intervals (CI) to determine vaccine effectiveness.

Main Results:

• In children aged 12-17, unvaccinated individuals had a significantly higher MIS-C incidence rate ratio (IRR: 22.9) compared to vaccinated individuals.
• In children aged 5-11, unvaccinated individuals also showed a higher MIS-C IRR (3.3) than vaccinated children.
• The Pfizer-BioNTech vaccine demonstrated a statistically significant protective effect against MIS-C in both studied age groups.

Conclusions:

• The Pfizer-BioNTech vaccine offers significant protection against the development of MIS-C in children aged 5-17 years.
• Vaccination is a key strategy to mitigate the risk of MIS-C following SARS-CoV-2 infection in pediatric populations.
• Despite its rarity, MIS-C prevention through vaccination is an important public health consideration for children.