Immunogenicity of SARS‐CoV‐2 vaccination in adolescents with cardiac disease

Background Although widely reported to affect older adults more, coronavirus disease 2019 (COVID‐19) also affects adolescents, especially those with co‐morbidities, including heart diseases. The safety and efficacy of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) mRNA vaccines has been established in healthy adolescents, yet there are few data for humoral and cellular immunogenicity in adolescents with cardiac diseases. Methods We evaluated anti‐spike antibodies, neutralizing activities, and interferon‐gamma production prior to and after SARS‐CoV‐2 vaccination in adolescents with cardiac diseases and healthy controls. Results Five healthy adolescents and 26 patients with cardiac diseases, including congenital heart disease (CHD, n = 10), dilated cardiomyopathy (DCM, n = 4), idiopathic pulmonary arterial hypertension (IPAH, n = 4), and those post‐heart transplantation (post‐HTx, n = 8) were enrolled. No severe adverse events, including myocarditis and pericarditis, were noted, even in patients with severe heart failure. Febrile events were noted after 21 of 62 injections (34%). All the healthy adolescents and 21 of the 26 patients (81%) showed sufficient elevation of neutralizing antibodies after the second dose of vaccination. Neutralizing antibodies and cellular immunity were absent in four of the eight post‐HTx patients and one with single ventricle CHD. There was no correlation between the anti‐spike and neutralizing antibody titers and interferon‐gamma levels. When comparing the clinical characteristics of the patients post‐HTx who did or did not acquire antibodies, there was no significant difference in the immunosuppressant types and trough levels. Conclusions SARS‐CoV‐2 mRNA vaccine has efficient immunogenicity for adolescents with CHD, IPAH, and DCM. Half of post‐HTx patients could not acquire sufficient humoral immunity.