ChAdOx1 nCoV-19 coronavirus vaccine: Long-term safety and immunological responses.

RATIONALE: Follow-up of pre-licensure trial participants potentially informs a vaccine's long-term safety profile.

DESIGN

This prospective study enrolled participants from the first clinical trials of ChAdOx1 nCoV-19 vaccine, many of whom subsequently received COVID-19 vaccines in the UK vaccination programme. Serious adverse events (SAEs) and adverse events of special interest (AESIs) were captured. AESI selection was based on Brighton Collaboration definitions.

RESULTS

Between September 2021 and April 2022, 4470 participants enrolled (58% female, median age 50 years); 3845/4470 (86.0%) completed the study. Median follow-up was 11.77 months; total follow-up was 48,116 person-months. There were 174 SAEs and 71 AESIs (33 events recorded as both) in 195 participants, including 5 deaths. Immunology data were available for a small subset of participants; total IgG against trimeric SARS-CoV-2 spike protein tended to increase during the study.

CONCLUSIONS

Although no emergent safety signals were detected, continued post-marketing surveillance remains imperative, particularly for neurological disorders.

EUDRACT NUMBER: 2021-003382-36.