Comparison of infection-induced and vaccine-induced immunity against COVID-19 in patients with cirrhosis

Background and Aims Immunity to SARS-CoV-2 can be infection or vaccine-induced. Cirrhosis is associated with vaccine hyporesponsiveness, but whether there is decreased immunity after SARS-CoV-2 infection in unvaccinated patients with cirrhosis is unknown. The objective of our study was to compare infection-induced and vaccine-induced immunity against COVID-19 among patients with cirrhosis. Methods This was a retrospective cohort study among US Veterans with cirrhosis between November 27, 2020, and November 16, 2021, comparing a vaccine-induced immunity group, defined as participants without a documented SARS-CoV-2 infection but fully vaccinated with two doses of an mRNA vaccine, and infection-associated immunity group, defined as unvaccinated participants who had a positive SARS-CoV-2 polymerase chain reaction (PCR). Both groups were propensity score matched for observed characteristics, including location, and the date of the immunity acquiring event, to control for the community prevalence of COVID-19 variants. The outcome was a positive SARS-CoV-2 PCR more than 60 days after previous infection in the infection-induced, or after full vaccination in the vaccine-induced immunity group. Results We compared 634 participants in the infection-induced immunity group with 27,131 participants in the vaccine-induced immunity group using inverse propensity of treatment weighting. Vaccine-induced immunity was associated with a reduced odds of developing SARS-CoV-2 infection (adjusted hazard ratio [aHR], 0.18; 95% confidence interval [CI], 0.16-0.20, p < 0.0001). On multivariable logistic regression, vaccine-induced immunity was associated with reduced odds of developing symptomatic (adjusted odds ratio [aOR], 0.36; 95% CI, 0.33-0.41, p < 0.0001), moderate/severe/critical (aOR, 0.27; 95% CI, 0.22-0.31, p < 0.0001), and severe or critical COVID-19 (aOR, 0.20; 95% CI, 0.16-0.26, p < 0.001), compared with infection-induced immunity. Conclusions In participants with cirrhosis, vaccine-induced immunity is associated with reduced risk of developing COVID-19, compared with infection-induced immunity.