Coronavirus disease 2019 vaccination is protective of clinical disease in solid organ transplant recipients

Abstract

Background: Clinical effectiveness of coronavirus disease 2019 (COVID-19) vaccination in solid organ transplant recipients (SOTRs) is not well documented despite multiple studies demonstrating sub-optimal immunogenicity.

Methods: We reviewed medical records of eligible SOTRs at a single center to assess vaccination status and identify cases of symptomatic COVID-19 from January 1 to August 12, 2021. We developed a Cox proportional hazards model using the date of vaccination and time since transplantation as a time-varying covariate with age and gender as potential time-invariant confounders. Survival curves were created using the parameters estimated from the Cox model.

Results: Among 1904 SOTRs, 1362 were fully vaccinated (96% received mRNA vaccines) and 542 were either unvaccinated (n = 470) or partially vaccinated (n = 72). There were 115 cases of COVID-19, of which 12 occurred in fully vaccinated individuals. Cox regression with the date of vaccination and time since transplantation as the time-varying co-variates showed that after baseline adjustment for age and sex, being fully vaccinated had a significantly lower hazard for COVID-19, hazard ratio (HR) = 0.29 and 95% confidence interval ([CI] 0.09, 0.91).

Conclusion: We found that 2-dose mRNA COVID-19 vaccination was protective of symptomatic COVID-19 in vaccinated versus unvaccinated SOTRs.

Tweet: COVID-19 vaccination was associated with a significantly lower hazard for symptomatic COVID-19 (HR 0.29; 95% CI 0.09, 0.91) among 1904 SOT recipients at a single center from January 1 to August 12, 2021.

Keywords: COVID-19 vaccine; SARS-CoV-2; clinical effectiveness; solid organ transplant.

Figure 1.

Estimated COVID-19 free survival curves based on a 56.9-year-old male (mean age and most frequent gender of the dataset). Although the curves are specific to an age and gender, there is little difference in curves across gender and age categories due to their insignificance in the model. The time for when the first, 25%, 50% and 75% of the subjects had been vaccinated occurred at day 1 (1/2/21), 64 (3/6/21), 97 (4/8/21) and 114 (4/25/21) respectively, with 1/1/21 as the start date (day 0). The top curve shows the expected COVID-19 free survival (based on estimated parameters) for a population of people all of whom were vaccinated at the date of the first vaccination (Jan 2). The next curve represents the expected experience of people who were all vaccinated at the date at which 25% of those ultimately vaccinated had received their vaccination. The next two curves are the same in principle but for dates when 50 and 75% were vaccinated. The bottom curve is the expected experience of people who were never vaccinated.