Real-world Effectiveness of the Pfizer-BioNTech BNT162b2 and Oxford-AstraZeneca ChAdOx1-S Vaccines Against SARS-CoV-2 in Solid Organ and Islet Transplant Recipients

Abstract

Background: The clinical effectiveness of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in immunosuppressed solid organ and islet transplant (SOT) recipients is unclear.

Methods: We linked 4 national registries to retrospectively identify laboratory-confirmed SARS-CoV-2 infections and deaths within 28 d in England between September 1, 2020, and August 31, 2021, comparing unvaccinated adult SOT recipients and those who had received 2 doses of ChAdOx1-S or BNT162b2 vaccine. Infection incidence rate ratios were adjusted for recipient demographics and calendar month using a negative binomial regression model, with 95% confidence intervals. Case fatality rate ratios were adjusted using a Cox proportional hazards model to generate hazard ratio (95% confidence interval).

Results: On August 31, 2021, it was found that 3080 (7.1%) were unvaccinated, 1141 (2.6%) had 1 vaccine dose, and 39 260 (90.3%) had 2 vaccine doses. There were 4147 SARS-CoV-2 infections and 407 deaths (unadjusted case fatality rate 9.8%). The risk-adjusted infection incidence rate ratio was 1.29 (1.03-1.61), implying that vaccination was not associated with reduction in risk of testing positive for SARS-CoV-2 RNA. Overall, the hazard ratio for death within 28 d of SARS-CoV-2 infection was 0.80 (0.63-1.00), a 20% reduction in risk of death in vaccinated patients (P = 0.05). Two doses of ChAdOx1-S were associated with a significantly reduced risk of death (hazard ratio, 0.69; 0.52-0.92), whereas vaccination with BNT162b2 was not (0.97; 0.71-1.31).

Conclusions: Vaccination of SOT recipients confers some protection against SARS-CoV-2-related mortality, but this protection is inferior to that achieved in the general population. SOT recipients require additional protective measures, including further vaccine doses, antiviral drugs, and nonpharmaceutical interventions.

Graphical abstract

FIGURE 1.

Study inclusion and exclusion criteria and patient flow. NHS, National Health Service; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

FIGURE 2.

Percentage of unvaccinated and vaccinated solid organ and islet transplant recipients through the study period. Numbers are shown on the graph. Recipients can be counted more than once in each month as they receive a vaccine. Numbers in each month don’t add up to summary data by the end of the study date because of patient deaths, incident transplants, and censoring.

FIGURE 3.

Number of laboratory-confirmed SARS-CoV-2 infections per month in solid organ and islet transplant recipients by vaccination status, compared with the general population in England, September 1, 2020, to August 31, 2021. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SOT, solid organ and islet transplant.

FIGURE 4.

Patient survival from date of laboratory-confirmed SARS-CoV-2 infection, by vaccination status. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

FIGURE 5.

Hazard ratios with 95% confidence intervals of risk of death within 28 d of laboratory-confirmed SARS-CoV-2 infection in solid organ and islet transplant recipients, by vaccination status and demographic characteristics. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SPK, simultaneous pancreas-kidney transplant.

FIGURE 6.

Patient survival from date of laboratory-confirmed SARS-CoV-2 infection, by vaccination status and vaccine type. AZ, Oxford University-AstraZeneca ChAdOx1-S; PF, Pfizer-BioNTech BNT162b2; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

FIGURE 7.

Hazard ratios with 95% confidence intervals of risk of death within 28 d of laboratory-confirmed SARS-CoV-2 infection in solid organ and islet transplant recipients, by vaccination status, vaccine type, and demographic characteristics. AZ, Oxford University-AstraZeneca ChAdOx1-S; PF, Pfizer-BioNTech BNT162b2; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SPK, simultaneous pancreas-kidney transplant.