TABLE 3. Effectiveness* of 2 doses of Pfizer-BioNTech vaccine against multisystem inflammatory syndrome in children among hospitalized patients aged 12–18 years — 24 pediatric hospitals, 20 U.S. states,† July–December 2021.
| Control groups | No. vaccinated§/Total (%) |
Adjusted VE, % (95% CI) | |
|---|---|---|---|
| MIS-C case patients | Control patients | ||
|
All controls
|
5/102 (4.9) |
65/181 (35.9) |
91 (78–97) |
| Test-negative |
5/102 (4.9) |
34/90 (37.8) |
92 (77–97) |
| Syndrome-negative |
5/102 (4.9) |
31/91 (34.1) |
89 (70–96) |
|
Sensitivity analysis
| |||
| MIS-C case patients with serologic evidence present¶ | 5/88 (5.7) | 61/161 (37.9) | 90 (75–96) |
Abbreviations: MIS-C = multisystem inflammatory syndrome in children; VE = vaccine effectiveness.
* VE estimates were based on odds of antecedent vaccination in MIS-C case-patients versus controls adjusted for U.S. Census region, continuous age in years, sex, and race/ethnicity (non-Hispanic White, non-Hispanic Black, non-Hispanic multiple race/other, Hispanic of any race, or unknown). Firth penalized regression was used for models with six or fewer vaccinated cases.
† Patients included vaccinated and unvaccinated persons aged 12–18 years enrolled from 24 pediatric hospitals in 20 states. Northeast: Boston Children’s Hospital (Massachusetts), Children's Hospital of Philadelphia (Pennsylvania), and Saint Barnabas Medical Center (New Jersey); Midwest: Akron Children’s Hospital (Ohio), Children’s Hospital and Medical Center: Nebraska (Nebraska), Children's Hospital of Michigan (Michigan), Children’s Mercy Kansas City (Missouri), Cincinnati Children’s Hospital Medical Center (Ohio), Lurie Children's Hospital of Chicago (Illinois), Mayo Clinic (Minnesota), Nationwide Children's Hospital (Ohio), and Riley Children's Hospital (Indiana); South: Arkansas Children’s Hospital (Arkansas), Children’s of Alabama (Alabama), Children's Healthcare of Atlanta (Georgia), Children’s Hospital of New Orleans (Louisiana), Medical University of South Carolina Children’s Health (South Carolina), Monroe Carell Jr. Children’s Hospital at Vanderbilt (Tennessee), Texas Children’s Hospital (Texas), University of Mississippi Medical Center (Mississippi), University of North Carolina at Chapel Hill Children’s Hospital (North Carolina), and University of Texas Southwestern Medical Center (Texas); West: Children’s Hospital Colorado (Colorado), Children’s Hospital Los Angeles (California), University of California San Diego-Rady Children’s Hospital (California), and University of California San Francisco Benioff Children’s Hospital Oakland (California).
§ COVID-19 vaccination status included the following two categories: 1) unvaccinated, defined as no receipt of any SARS-CoV-2 vaccine before hospitalization for current illness and 2) fully vaccinated, defined as receipt of both doses of a 2-dose Pfizer-BioNTech vaccination ≥28 days before illness onset.
¶ Analysis excluded 14 MIS-C case-patients who were positive by reverse transcription-polymerase chain reaction only with no serologic evidence of previous infection and 20 controls matched to these patients, given potential misclassification of patients with severe acute COVID-19.