BACKGROUND: Solid organ transplant (SOT) recipients have increased morbidity and mortality risk from coronavirus disease 2019 (COVID-19). OBJECTIVES: This study aimed to evaluate the immunogenicity of COVID-19 vaccines in SOT recipients. DATA SOURCES: Electronic databases were searched for eligible reports published from December 1, 2019 to May 31, 2022. STUDY ELIGIBILITY CRITERIA: We included reports evaluating the humoral immune response (HIR) or cellular immune response (CIR) rate in SOT recipients after COVID-19 vaccines. PARTICIPANTS: SOT recipients who received COVID-19 vaccines. ASSESSMENT OF RISK OF BIAS: We used the Newcastle-Ottawa Scale to assess bias in case-control and cohort studies. For the randomized controlled trials, the Jadad Scale was used. METHODS OF DATA SYNTHESIS: We used a random-effects model to calculate the pooled rates of immune response with 95% confidence intervals (CI). We used a risk ratio (RR) with 95% CI for a comparison of immune responses between SOT and healthy controls. RESULTS: A total of 91 reports involving 11,886 transplant recipients (lung: 655, heart: 539, liver: 1,946 and kidney: 8,746) and 2,125 healthy controls revealed pooled HIR rates after the 1st, 2nd, and 3rd COVID-19 vaccine doses in SOT recipients were 9.5% (95% CI: 7%-11.9%), 43.6% (95% CI: 39.3%-47.8%) and 55.1% (95% CI: 44.7%-65.6%), respectively. For specific organs, the HIR rates were still low after 1st dose vaccination (lung: 4.4%; kidney: 9.4%; heart: 13.2%; liver: 29.5%) and 2nd dose(lung: 28.4%; kidney: 37.6%; heart: 50.3%; liver: 64.5%). CONCLUSION: A booster vaccination enhances the immunogenicity of COVID-19 vaccines in SOT, however, a significant share of the recipients still has not built a detectable HIR after the 3rd dose. This finding calls for alternative approaches, including the use of monoclonal antibodies. In addition, lung transplant recipients need urgent booster vaccination to improve the immune response.
- All age groups
- Vaccine/vaccination
- COVID-19
- Efficacy/effectiveness
