Second Pfizer Jab Taken After Shorter Interval May Have Higher Myocarditis, Pericarditis Risk, Doctor Says

A vial of the Pfizer-BioNTech COVID-19 vaccine in a file photograph. Justin Sullivan/Getty Images

An 11-year-old Hong Kong girl vaccinated with the Pfizer-BioNTech vaccine had symptoms of myocarditis.

Since then, the Hong Kong Centre for Health Protection extended the interval between the first and second doses of the Pfizer-BioNTech vaccine from three to eight weeks for people between 18 and 59.