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What will be the adverse reactions to the vaccines among children?


Adverse reactions to the vaccines among small children now and in the future have not yet been presented. But here are some details from Pfizer about teenagers:

Pfizer and BioNTech Share Detailed Update to the Results from 6 Month Safety and Efficacy Data Analysis of Landmark COVID-19 Vaccine Study

  • The Pfizer-BioNTech COVID-19 Vaccine may not protect all vaccine recipients
  • ……
  • In a clinical study, adverse reactions in adolescents 12 through 15 years of age included pain at the injection site (90.5%), fatigue (77.5%), headache (75.5%), chills (49.2%), muscle pain (42.2%), fever (24.3%), joint pain (20.2%), injection site swelling (9.2%), injection site redness (8.6%), lymphadenopathy (0.8%), and nausea (0.4%)
  • Following administration of the Pfizer-BioNTech COVID-19 Vaccine, the following have been reported outside of clinical trials:
    • severe allergic reactions, including anaphylaxis, and other hypersensitivity reactions, diarrhea, vomiting, and pain in extremity (arm)
    • myocarditis and pericarditis

Additional adverse reactions, some of which may be serious, may become apparent with more widespread use of the Pfizer-BioNTech COVID-19 Vaccine

Reports in dominant media say that reported myocarditis and pericarditis after the vaccine are “rare” and “mild”. However, once in a while, there are reports of deaths in local media. But no international statistics seem to be collected.

Since April 2021, increased cases of myocarditis and pericarditis have been reported in the United States after mRNA COVID-19 vaccination (Pfizer-BioNTech and Moderna), particularly in adolescents and young adults. There has not been a similar reporting pattern observed after receipt of the Janssen COVID-19 Vaccine (Johnson & Johnson).

In most cases, patients who presented for medical care have responded well to medications and rest and had prompt improvement of symptoms. Reported cases have occurred predominantly in male adolescents and young adults 16 years of age and older.
Page last reviewed: August 23, 2021

Myocarditis is an uncommon, potentially life-threatening disease that presents with a wide range of symptoms in children and adults. Myocarditis Lori A.Blauwet, Leslie T.Cooper, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, 2010,

In some cases of non-COVID-19 vaccine-related myocarditis, the disease can progress to dilated cardiomyopathy and chronic heart failure, with evidence implicating myocarditis in 12% of sudden deaths in adults aged under 40. Likewise, the long-term prognosis of pericarditis is good, but it can become recurrent and rarely patients may develop constrictive pericarditis.