Multisystem Inflammatory Syndrome in Children by COVID-19 Vaccination Status of Adolescents in France

Reported cases of multisystem inflammatory syndrome in children aged 12–20 years in the USA who received a COVID-19 vaccine, December, 2020, through August, 2021: a surveillance investigation

“…Multisystem inflammatory syndrome in adults was not reported in clinical trials of COVID-19 vaccines used in the USA, and MIS-C was not observed in the 46 000 individuals aged 16 years or older who participated in safety clinical trials for BNT162b2. 10 , 25 Globally, MIS-C in individuals who had received a COVID-19 vaccine has been described in detail in the literature for eight individuals younger than 21 years, 22 , 26 , 27 , 28 , 29 , 30 , 31 excluding aggregate counts from larger analyses assessing the effect of vaccination on preventing MIS-C. 32 , 33 From the USA, two reports included three cases that are also in our surveillance results, 22 , 26 and one report described a 14-year-old child with evidence of previous SARS-CoV-2 infection (positive anti-nucleocapsid antibody test) with MIS-C onset 2 months after a second dose with BNT162b2. 31 From outside the USA, we found reports of two individuals without evidence of previous or recent SARS-CoV-2 infection and who tested negative for anti-nucleocapsid antibodies: from Denmark, a 17-year-old with MIS-C onset 5 days after dose two of BNT162b2; 28 and from Turkey, a 12-year-old with onset 27 days after dose one of BNT162b2.…”

Effectiveness of BNT162b2 (Pfizer-BioNTech) mRNA Vaccination Against Multisystem Inflammatory Syndrome in Children Among Persons Aged 12–18 Years — United States, July–December 2021

“…¶ ¶ VE was assessed by comparing the odds of antecedent vaccination between MIS-C patients and hospitalized controls without evidence of SARS-CoV-2 infection during July 1-December 9, 2021. Case-patients met CDC criteria for MIS-C,*** which † † https://overcomecovid.org/ § § CDC recommendation for pediatric COVID-19 vaccine for children aged [5][6][7][8][9][10][11] Vaccination status was verified through searches of state immunization information systems, electronic medical records, or other sources, including documentation from pediatricians or patient immunization cards. For this analysis, persons were categorized as unvaccinated or fully vaccinated on or before the case-patient hospitalization date.…”

“…Prelicensure randomized trials in persons aged ≥5 years documented high vaccine efficacy and immunogenicity ( 5 ), § and real-world studies in persons aged 12–18 years demonstrated high vaccine effectiveness (VE) against severe COVID-19 ( 6 ). Recent evidence suggests that COVID-19 vaccination is associated with lower MIS-C incidence among adolescents ( 7 ); however, VE of the 2-dose Pfizer-BioNTech regimen against MIS-C has not been evaluated. The effectiveness of 2 doses of Pfizer-BioNTech vaccine received ≥28 days before hospital admission in preventing MIS-C was assessed using a test-negative case-control design ¶ among hospitalized patients aged 12–18 years at 24 pediatric hospitals in 20 states ** during July 1–December 9, 2021, the period when most MIS-C patients could be temporally linked to SARS-CoV-2 B.1.617.2 (Delta) variant predominance.…”

COVID-19 in children: From afterthought to unknown

“…Overall, it will be crucial to understand if children developing myocarditis after vaccination are those susceptible to MIS-C. Importantly, it has been recently shown how mRNA vaccine against SARS-CoV-2 was able to significantly reduce the incidence of MIS-C. 12 In terms of immunogenicity, a higher dose (100 μg) of mRNA vaccine was shown to induce higher CD4 T cell immunity compared to a lower dose (25 μg). There are few hypotheses on how differences in quantity of mRNA delivered through the vaccination could impact safety and possibly heart disease.…”