COVID-19 vaccination in adults with congenital heart disease: Real-world data from an Italian tertiary centre.

Background: real-world data on COVID-19 vaccine safety, immunogenicity and acceptance in adults with congenital heart disease (ACHD) are lacking. Methods: ACHD patients who were offered COVID-19 vaccination from January to June 2021 were included. Data on adverse events, on patients' attitude towards vaccination and antispike IgG titre were retrospectively collected. A group of healthy individuals with similar age and sex undergoing vaccination was included for comparison. Results: 208 patients followed in a single ACHD tertiary centre (33.3 [26-45] years, 54% male) received COVID-19 vaccine, 65% vaccinated at our institution: 199 (96%) received Pfizer-BioNTech BNT162b2 vaccine, 4 (2%) Moderna-1273 and 5 (2%) AstraZeneca-ChAdOx1. Median follow-up after vaccination was 79 [57-96] days. No major adverse event was reported and the incidence of minor events was not different between ACHD patients and the control group. One patient was diagnosed with acute pericarditis. There were two deaths unrelated to the vaccine during follow-up. Three (1.5%) vaccinated patients tested positive for COVID-19. Antispike IgG titre, available in 159 (76%) patients, was 1334 [600-3401] BAU/ml, not significantly different from the control group (p=0.2). One patient with Fontan failure was seronegative. Advanced physiological stage was associated with lower antibody response, independently from previous viral exposure (p<0.0001). Fourteen percent refused COVID-19 vaccination at our institution. However, 50% of vaccinated patients declared to have been influenced by the discussion with the ACHD cardiologist and 66% of those vaccinated in situ reported that undergoing COVID-19 vaccination at the ACHD centre made them feel safer. Conclusion: COVID-19 vaccines appear safe in ACHD with satisfactory immunogenicity. However, the most vulnerable patients showed lower antibody response. ACHD team may play a key role in vaccine acceptance.