The Impact of Vaccination on COVID-19 Infections and Hospitalizations in Individuals with Sickle Cell Disease

Background: Sickle cell disease (SCD) is an inherited red blood cell disorder that causes chronic hemolytic anemia and recurrent vascular occlusion, leading to chronic pain, organ damage, and increased susceptibility to infections. Patients (pts) with SCD are at increased risk for severe complications from COVID-19 (C19) due to their chronic health conditions, including endothelial dysfunction and hypercoagulability. C19 vaccinations have been shown to decrease hospitalizations and morbidity. Despite the availability of vaccines, many SCD patients remain unvaccinated, highlighting the need for targeted interventions and education. In order to better understand the impact of vaccinations on SCD outcomes we evaluated frequency of infection, hospitalizations and severe complications of C19 in SCD pts at a single institution. Methods: This retrospective study included adult patients (> 18 years) followed at the Comprehensive Adult Sickle Cell program at Newark Beth Israel Medical Center from 2020 to 2022. Pregnant women were excluded. We reviewed data on demographics, sickle cell genotypes, C19 vaccination status, infections, hospitalizations, and thromboembolic events. Of the 344 patients, 304 (83.4%) with verifiable vaccination status were included in the final analysis. Primary outcomes included C19 infection rates, hospitalization rates, length of hospital stay, ICU admissions, and severe complications (Acute Chest Syndrome (ACS), venous thromboembolism (VTE), C19 pneumonia, and hypoxic respiratory failure). Differences between vaccinated and unvaccinated groups were evaluated using chi-square tests, with significance set at p < 0.05. Results: Of the 304 SCD patients (pts) in the cohort, 210 (69%) had the SS/Sβo. 171/304 (56%) were vaccinated (104 females, 67 males), and 133/304 (43.8%) were unvaccinated (84 females, 49 males). Ages ranged from 18 to 82 years (median 33 years). A total of 112/304 (36.8%) tested positive for C19, with 74/112 (66%) were unvaccinated and 38 /112 (34%) were vaccinated ( p = 0.008378). Hospitalization rates were significantly higher in the unvaccinated group, with 51/68 (75%) being unvaccinated and 17/68 (25%) being vaccinated (p = 0.013101). Of the 51 unvaccinated hospitalized pts, 38 (74.5%) required non-invasive oxygen, compared to the 7/17 (41.2%) vaccinated pts. (0.11877). The unvaccinated group had a higher incidence of ICU admissions and mechanical ventilation. Unvaccinated pts also had longer hospital stays than vaccinated patients (7.84 vs. 5.50 days respectively). Severe complications including ACS, VTE and hypoxic respiratory failure were more common in hospitalized unvaccinated pts 38/74 compared to vaccinated pts 10/38 ( p = 0.011247). Vaso-occlusive Crisis was comparable in both groups. Conclusion: In our SCD cohort, C19 vaccination significantly reduced the risk of infection and resulted in milder disease courses. Vaccinated pts experienced lower hospitalization rates, fewer severe complications, and shorter hospital stays compared to their unvaccinated counterparts. Other preventive measures may have contributed to these outcomes but were not evaluated in this study. However, these findings underscore the critical role of C19 vaccination in mitigating severe outcomes and complications in SCD pts. Continued public health initiatives are necessary to promote vaccination among this vulnerable population. Further research should explore additional preventive strategies and interventions to improve health outcomes for SCD pts. Integrating C19 vaccination programs with routine SCD care could enhance patient outcomes.