Vaccinations have been shown to produce a phenomenon called trained immunity. Effects include (a) increased responsiveness to pathogens other than the one vaccinated against, and (b) reduced chronic inflammation in later life. Trained immunity is well studied for the former phenomenon, but less well studied for the latter; questions remain as to whether different forms of vaccination for the same pathogen have different effects, for example. Correlations between later life vaccination and reduced risk of age-related disease and dysfunction have been observed, but it remains an open question as to whether this reflects trained immunity effects versus late life vaccination, a voluntary process, selecting for people who tend to take better care of their health in other ways as well.
A new global systematic literature review and meta-analysis has shown that herpes zoster vaccination, used to prevent shingles, is associated with a statistically significant lower risk of heart attack and stroke. The study found that herpes zoster vaccination, with either the recombinant herpes zoster vaccine (RZV) or the live attenuated zoster vaccine (ZVL) was associated with an 18% and 16% reduction in risk of cardiovascular events in adults 18 and 50 years or older, respectively. In studies that reported on cardiovascular event absolute risk, the absolute rate difference ranged from 1.2 to 2.2 fewer events per 1,000 person-years.
The global systematic literature review was conducted using three scientific literature databases, and a meta-analysis was conducted of phase 3 randomized controlled trials and observational studies assessing the effect of herpes zoster vaccination on cardiovascular events. 19 studies were included in the review; eight observational studies and one randomized controlled trial (a pooled safety analysis of two Phase 3 randomized trials; not designed or powered to evaluate the effects of herpes zoster vaccination against cardiovascular events), met the meta-analysis inclusion criteria for herpes zoster vaccination effectiveness on cardiovascular events. Across all nine studies, 53.3% of participants were male. Seven studies reported mean ages from 53.6 years to 74.0 years.
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