Multiple large-scale epidemiological and clinical studies consistently demonstrate that administering a COVID-19 vaccine to individuals who have previously recovered from the virus enhances their humoral and cellular immunity, resulting in superior protection against reinfection compared to natural immunity alone.
The retrieved literature robustly supports the claim that hybrid immunity (vaccination following natural infection) improves immunity against reinfection and provides more durable and potent protection than natural immunity alone. Numerous cohort studies, reviews, and population-wide investigations (e.g., Nordström et al., 2022; Goldberg et al., 2022) confirm that vaccination post-infection reinforces neutralizing antibody titers and reduces the risk of subsequent SARS-CoV-2 infection.