Dear Editor

Since its characterization in December 2019, the novel coronavirus, SARS-COV-2, has been responsible for more than 6.3 million deaths worldwide. In the United States alone, there have been over 84 million cases, with case numbers continuing to rise. Despite the herculean vaccination effort since emergency approval in December 2020, only 61% of eligible Americans were fully vaccinated 1 year later. We set out to investigate the rate of vaccine uptake among solid-organ transplant recipients (SOTR), a high-risk population, and to understand the attitudes and perceptions that motivate vaccine hesitancy.

The questionnaire was designed by 5 members of our study team. We initially surveyed an online focus group (n = 9) comprising heart and lung transplant recipients followed within our practice at the University of Maryland Medical Center (UMMC). Our goal was to evaluate the understandability and appropriateness of the content and response options.

We then emailed the survey to 1718 SOTR in May 2021 who were actively followed within our transplant program. Of the 283 respondents, 49% had received a renal transplant, 34% a liver transplant, and the remainder were recipients of lung (8%), pancreas, or multiple organ transplants. In addition to vaccination status, the survey queried perceptions about the risk of COVID-19 and vaccine efficacy/safety.

Of respondents, 265 (93.6%) were already vaccinated and only 9 (3%) indicated that they were unwilling to be vaccinated. The remaining 3.4% of respondents were not yet vaccinated but indicated a willingness to do so in the near future. Among the reasons cited for vaccine hesitancy among those 9 patients were a perceived lack of efficacy, a lack of sufficient testing/evidence, and concerns about vaccine safety. As illustrated in Figure 1, an overall high degree of confidence in vaccine safety and efficacy was noted, even as concern for contracting or spreading the virus remained low.

Our population showed a remarkable willingness to undergo vaccination for COVID-19 at a rate far above that of the general population. We believe that formalized educational offerings as well as the high level of trust in provider opinion contributed to the excellent vaccine uptake rate. However, the overall response rate of 16.5% does raise the concern of response bias and represents a limitation to this study. Despite this low response rate, our data are in line with similar studies showing 91% acceptance in liver transplant recipients after education.¹

To our knowledge, our study is the first of its kind among SOTR in the United States. Our study demonstrates a rate of vaccine hesitancy similar to published Italian² and Australian³ studies (n = 190 and 473, respectively). However, a similar study from Fundan University in China showed nearly 73% rate of vaccine refusal among their 813 participants.⁴ These differences may represent differing levels of public trust in the various regionally available vaccines.

References:

1. Giannini EG, Marenco S. High acceptance rate of COVID-19 vaccination in liver transplant recipients. J Hepatol. 2021;75(2):483-484. doi:10.1016/j.jhep.2021.05.009
   CrossRef - PubMed
   
2. Costantino A, Invernizzi F, Centorrino E, Vecchi M, Lampertico P, Donato MF. COVID-19 vaccine acceptance among liver transplant recipients. Vaccines (Basel). 2021;9(11):1314. doi:10.3390/vaccines9111314
   CrossRef - PubMed
   
3. Tharmaraj D, Dendle C, Polkinghorne KR, Mulley WR. Kidney transplant recipients' attitudes toward COVID-19 vaccination and barriers and enablers to vaccine acceptance. Transpl Infect Dis. 2022;24(1):e13749. doi:10.1111/tid.13749
   CrossRef - PubMed
   
4. Chen T, Li X, Li Q, et al. COVID-19 vaccination hesitancy and associated factors among solid organ transplant recipients in China. Hum Vaccin Immunother. 2021;17(12):4999-5006. doi:10.1080/21645515.2021.1984133
   CrossRef - PubMed