The association between herpes zoster (HZ) and an increased risk of stroke is well documented.1,2 A large cohort study including 1.38 million Medicare beneficiaries, reported a lower incidence of ischemic and hemorrhagic stroke in the recipients of Zoster Vaccine Live (ZVL).3 A stronger association was found among those aged 66-69 years compared to those ≥80 years.3 Data was presented by Dr. Quanhe Yang from the Centers for Disease Control and Prevention (CDC) in Atlanta, at the International Stroke Conference (ISC) 2020 in Los Angeles.3 The additional benefit of herpes zoster vaccination further supports its recommendation in the elderly population by the CDC.4
The prevalence of HZ, a viral disease caused by the reactivation of varicella zoster virus (VSV) is estimated to be 17-25% in Hong Kong.5,6 Due to the increasing risk with age, the CDC recommends HZ vaccination in those aged 50 years or above.4 In particular, recombinant zoster vaccine (RZV) is the preferred vaccine for adults aged 50 years and older, whereas ZVL may be used as an alternative in those aged 60 years and older.4 The association between HZ and subsequent increased risk of stroke has been reported in several studies among other macrovascular disorders.1,2 Possible mechanisms include vasculopathy caused by VZV or inflammation associated with systemic infection which creates an environment in which the blood is more prone to clotting.1
A recent study presented by Dr. Yang, at the ISC 2020, was the first to examine the association between HZ vaccination with ZVL and the risk of stroke. The health records of over 1.38 million Medicare beneficiaries aged 66 years without a history of stroke or who received ZVL during 2008-2014 were reviewed and compared to a same-sized population of matched controls who did not receive ZVL.3 The association between ZVL and composite fatal/non-fatal incident stroke outcomes were examined using Coz proportional hazard models.3
During a follow-up with a median duration of 3.9 months, Dr. Yang and his colleagues reported a total of 42,467 stroke events among ZVL recipients over 5,890,113 person years.3 The stroke events were further stratified into 33,510 acute ischemic strokes (AIS) and 4,318 hemorrhagic strokes.3 For the matched controls, more stroke events (48,139 in total) occurred over 5,693,943 person years, of which 39,334 were AIS and 4,713 were hemorrhagic strokes.3 Lower incidence rates per 1000-person years were also observed in those who received ZVL compared to those who did not, for all strokes (7.18 vs. 8.43), AIS (5.4 vs. 6.53) and hemorrhagic strokes (0.73 vs. 0.82; p<0.001).3 There was an overall reduction of 16% in stroke risk, 18% in AIS and 12% in hemorrhagic stroke.3 Furthermore, the association between ZVL and reduced stroke risk was stronger among beneficiaries 66-79 years compared to those 80 years or above (p=0.020).3
Despite the availability of licensed HZ vaccines, there is a relatively high incidence of HZ with approximately one million cases per year in the United States.4 The new findings that suggest additional benefits of HZ vaccination are promising and may encourage more clinicians and patients to follow the CDC’s recommendation for the prevention of HZ in the future.
1. Marra F et al. A meta-analysis of stroke risk following herpes zoster infection. BMC Infect Dis. 2017;17(1):198.
2. Breuer J et al. Herpes zoster as a risk factor for stroke and TIA: a retrospective cohort study in the UK. Neurology. 2014;83(2):e27-33.
3. YANG Quanhe et al. Abstract TP493: Herpes Zoster Vaccine Live And Risk For Stroke Among Medicare Beneficiaries: Population Based Matched Cohort Study. Stroke. 51(Suppl_1):ATP493-ATP493.
4. Shingles | Clinical Overview – Varicella Vaccine | Herpes Zoster | CDC. https://www.cdc.gov/shingles/hcp/clinical-overview.html. Published August 21, 2019. Accessed March 5, 2020.
5. Survey on Herpes Zoster Vaccine. https://www.hkupop.hku.hk/english/header.html. Accessed March 6, 2020.
6. The Hong Kong Practitioner. http://www.hkcfp.org.hk/Upload/HK_Practitioner/2019/hkp2019vol41Sep/original_article.html. Accessed March 6, 2020.