Evaluating the Effectiveness of COVID-19 Vaccines in Adults with Sickle Cell Disease during the Omicron Period of COVID-19 Pandemic

BACKGROUND:

The Omicron variant, one of the variants causing the coronavirus disease of 2019 (COVID-19), was first identified in November 2021 and became the predominant variant in 2022. Although causing less severe disease, this variant and its subvariants have been associated with increased transmissibility and limited protection despite vaccination and prior infection (PMID: 35622357). Individuals with sickle cell disease (SCD) are particularly at greater risk of severe illness and death (PMID: 35060794). As more people with SCD are getting vaccinated and restrictions are being lifted during the Omicron period of the pandemic, the impact on this group has yet to be extensively studied. The study aims to determine the effectiveness of COVID-19 vaccination during this period among individuals with SCD. Additionally, the study aims to examine various factors that can influence the likelihood of COVID-19 infection and severity among SCD individuals.

METHODS:

This multicenter retrospective study was conducted at three hospital centers in Michigan. A total of 101 SCD adult patients (age ≥ 18 years old) who had emergency and inpatient encounters from January 1 to December 31, 2022, were included in the study. Electronic medical records were reviewed to gather patient data such as demographics, details of COVID-19 infection, underlying comorbidities, and other clinical information, while the immunization registry in Michigan was used to obtain COVID-19 vaccination status. Multivariable regression analysis was conducted to determine the clinical correlation between COVID-19 vaccination status and infection and to examine various factors influencing COVID-19 severity. Statistical analyses were performed using SPSS version 28.0 statistical software, and a p-value of <0.05 was considered statistically significant.

RESULTS:

Of the 101 adults with SCD included in the study, 97 % were Black, with a mean age of 40 years. The majority had the hemoglobin SC (54%) or SS (35%) genotype. 42 individuals with SCD and confirmed COVID-19 were identified. The most reported chief complaints in the emergency rooms at the time of COVID-19 diagnosis were myalgia and chest pain. Interestingly, individuals with SCD and a history of acute chest syndrome were over 3 times more likely to have a COVID-19 infection diagnosis than those without a history of acute chest syndrome (OR=3.68, 95% CI=1.47-9.17). This was likely due to a significant overlap between the symptoms of acute chest syndrome and COVID-19 warranting emergency care visits.

47.5 % of the individuals with SCD were vaccinated by December 2022. Among these, 12.5% were partially vaccinated, 50% were fully vaccinated, and 37.5% had a booster. COVID-19 infection was significantly higher among the nonvaccinated compared to vaccinated individuals (55% vs. 27%, p=0.01). The mean interval days from the latest dose of COVID-19 vaccination to COVID-19 infection was 297.9 ± 160.5 days. The study found that COVID-19 vaccination lowered the infection risk among SCD individuals by over 70% if they have received at least one dose of the vaccine (OR=0.27, 95% CI=0.10-0.77). There was also a significant difference in preventing COVID-19 infection among the different vaccination subgroups of partial, full, and booster (33% vs. 25% vs. 28%, p=0.045). The results of the multivariable logistic regression analysis showed that none of the factors, such as obesity, pre-existing cardiac history, pulmonary history, renal disease, stroke, or transient ischemic attack, were found to be significantly associated with COVID-19 severity in this sample population.

CONCLUSION:

Receiving at least one dose of the COVID-19 vaccine can offer protection among individuals with SCD, even with the emergence of Omicron and its subvariants during the COVID-19 pandemic. Additionally, it is crucial that individuals with SCD remain vigilant and seek medical care if they experience chest pain, as this could be the only symptom of COVID-19 among this population.