Although a significantly increased risk for stroke occurred in patients diagnosed with herpes zoster virus infection within the past month, the risk was decreased among those vaccinated against varicella zoster virus (VZV) prior to infection onset, according to results of a study published in Clinical Infectious Diseases.
Researchers conducted a retrospective case-control study between January 2010 and January 2020 using patient data captured from Veterans Affairs’ Corporate Data Warehouse. They sought to assess the risk for stroke among patients (case group) diagnosed with herpes zoster infection within the past 30 days, as well as the effect of prior vaccination against VZV infection on patients’ stroke risk. A control group also was included in the analysis, comprising patients with no history of herpes zoster infection during the same period. The first incidence of stroke was determined via discharge diagnostic codes, and time to first stroke incidence was defined as the number of days from the index date to the first occurrence of stroke.
Among patients in the case (n=71,911) and control (n=2,093,594) groups, the mean age was 71 and 69 years, 9.5% and 9.1% were vaccinated against VZV with a live vaccine, and 2.2% and 9.1% were vaccinated against VZV with a recombinant vaccine, respectively. The most common comorbidities between case vs control patients included uncomplicated diabetes (11.1% vs 15.7%), chronic obstructive pulmonary disease (7.2% vs 8.4%), kidney failure (5.3% vs 6.4%), and solid tumor cancer (5.7% vs 6.7%).
Stroke within 30 days occurred among 102 (0.14%) and 1687 (0.08%) of patients in the case and control groups, respectively. Compared with patients in the control group, the risk for stroke within 30 days after onset of herpes zoster infection was significantly increased among those in the case group (odds ratio [OR], 1.93; 95% CI, 1.57-2.4; P <.0001). After 1 year, the risk for stroke remained significantly increased among patients in the case group (OR, 1.62, 95% CI, 1.49-1.75). Prior receipt of both recombinant (OR, 0.57; 95% CI, 0.46-0.72; P <.0001) and live (OR, 0.77; 95% CI, 0.65-0.91; P =.002) VZV vaccination was associated with a significantly decreased risk for stroke.
A subgroup analysis was performed among 71,911 patients in the case group to assess the effect of VZV vaccination on the risk for stroke. Results showed that the median time to first stroke occurrence was significantly decreased among vaccinated vs unvaccinated patients (54.5 [IQR, 21-71) vs 30 [IQR, 22-37] days).
Multivariable logistic regression was used to compare the risk for stroke between patients younger than 50 years vs those 50 years and older. Results showed that patients 50 years and older had a significantly increased risk for stroke (OR, 2.35; 95% CI, 1.68-3.29), and recent herpes zoster infection significantly increased patients’ stroke risk (OR, 1.94; 95% CI, 1.58-2.37).
This study may have limited generalizability as the patient population comprised veterans, most of whom were older men. Other limitations include the retrospective design, the small number of vaccinated patients, and that zoster vaccines were not available during the entire study period.
“With the significant impact stroke can have on a patient’s mortality and morbidity, the results of this study may encourage vaccination against herpes zoster,” the researchers concluded.
Parameswaran GI, Wattengel BA, Chua HC, et al. Increased stroke risk following herpes zoster infection and protection with zoster vaccine. Clin Infect Dis. Published online July 7, 2022. doi: 10.1093/cid/ciac549