Patients Receiving Organ Transplants Undervaccinated Against Influenza, Pneumococcus

Vaccination rates against influenza and pneumococcus were lower in patients receiving organ transplants who lived outside of urban areas and had lower socioeconomic status.

Socioeconomic status (SES) and area of residence were 2 factors that were associated with patients with organ transplants being undervaccinated against influenza and pneumococcus (Streptococcus pneumoniae), according to a study published in Transplant Infectious Disease.

Patients receiving a solid organ transplant (SOT) have lower morbidity and mortality when they are not vaccinated, leading to the recommendation of receiving the yearly influenza vaccine for adult SOT candidates and recipients. However, health care disparities could cause a difference in vaccine access and uptake in these patients. This study aimed to evaluate the vaccination rates for SOT recipients based on demographic factors like age, race, ethnicity, rural status, and SES.

This study was population based and used the Rochester Epidemiology Project (REP) to collect data from participants. The REP included health care records from the Olmsted Mecial Center, Mayo Clinic, Mayo Clinic Health System, Olmsted County Public Health Services, Zumbro Valley Health Center, and other health care institutions located in southern Minnesota and western Wisconsin. Data were obtained from June 1, 2010, to June 30, 2020.

The Housing-based Socioeconomic Status (HOUSES) index was used to measure individual SES, which was used to determine the association between vaccination in patients with an SOT aged between 19 and 64 years. Medical records were used to collect demographic data. Patients were included in the cohort using the date of their first SOT within the time of the study. Rural status was determined by the 2010 Rural-Urban Commuting Area codes. Vaccination data were obtained from the state immunization registry.

There were 458 participants included in this study; the median age was 50 years, more men were included (57%), and the population was mostly White (83%). Most participants had a kidney transplant (70%) and the least common organ transplant was lung (7%). More than a third of the participants had had a history of smoking (38.2%).

A total of 85% of participants had received 1 dose of the influenza vaccine and 74% had received 2 or more influenza vaccines. The 10-year period saw an average vaccination rate of 56% (range, 57%-63%) for the influenza vaccine. The median (IQR) time spent undervaccinated was 26 (12-53) months, with only 6% participants never undervaccinated.

Higher SES was associated with higher influenza vaccination when comparing quartile 3 (second-highest SES) and quartile 1 (lowest SES) (rate ratio [RR], 1.147; 95% CI, 1.004-1.305). Quartile 3, the second-highest SES category, had the highest vaccination rate. Participants living in urban areas were more likely to have received an influenza vaccine compared with their suburban (RR, 0.801; 95% CI, 0.671-0.956) and rural (RR, 0.874; 95% CI, 0.718-1.065) counterparts. A lower mean difference of 3.25% (95% CI, –7.23 to 0.73) in influenza vaccination rate was found when comparing the first 3 years post transplant with the remaining years.

A total of 55.8% of participants were up to date on pneumococcal vaccines, with 81.8% of all SOT patients having received at least 1 vaccine. Only 68.1% of patients who had received at least 1 vaccine were up to date on pneumococcal vaccines. Patients with heart transplants were less likely to be up to date on their vaccines compared with patients with kidney transplants (odds ratio [OR], 0.509; 95% CI, 0.292-0.889).

Pneumococcal vaccination was also associated with geographic region, as people in suburban areas were 62% less likely to be up to date (OR, 0.386, 95% CI, 0.208-0.715) and rural areas were 44% less likely to be up to date (OR, 0.568; 95% CI, 0.404-0.798) compared with those in urban areas.

There were some limitations to this study. The study covered only 4 counties in southeastern Minnesota, which encompass primarily White and non-Hispanic people. The researchers recommended that future studies include higher proportions of Black and Hispanic participants to evaluate the relationship between vaccination and race. Patients who were 65 years and older were also not included in this study. Federally administered vaccines were likewise not included.

The researchers concluded that patients who received an SOT were undervaccinated in the region of southeastern Minnesota. Patients living outside of urban areas and with lower SES were at particular risk of going unvaccinated for influenza and pneumococcal diseases, which could lead to higher morbidity and mortality from infection.


Felzer JR, Rutten LJF, Wi CI, et al. Disparities in vaccination rates in solid organ transplant patients. Transpl Infect Dis. Published online January 30, 2023. doi:10.1111/tid.14010

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