Chen YC, Ho CH, Liu TH, et al. Long-term risk of herpes zoster following COVID-19: A retrospective cohort study of 2 442 686 patients. J Med Virol. 2023 Apr;95(4):e28745. doi: 10.1002/jmv.28745. (Original study)

The long-term risk of herpes zoster (HZ) after recovery from a SARS-CoV-2 infection is unclear. This retrospective cohort study assessed the risk of HZ in patients following a COVID-19 diagnosis. This retrospective, propensity score-matched cohort study was based on the multi-institutional research network TriNetX. The risk of incident HZ in patients with COVID-19 was compared with that of those not infected with SARS-CoV-2 during a 1-year follow-up period. Hazard ratios (HRs) and 95% confidence intervals (CIs) of HZ and its subtypes were calculated. This study identified 1 221 343 patients with and without COVID-19 diagnoses with matched baseline characteristics. During the 1-year follow-up period, patients with COVID-19 had a higher risk of HZ compared with those without COVID-19 (HR: 1.59; 95% CI: 1.49-1.69). In addition, compared with the control group patients, those with COVID-19 had a higher risk of HZ ophthalmicus (HR: 1.31; 95% CI: 1.01-1.71), disseminated zoster (HR: 2.80; 95% CI: 1.37-5.74), zoster with other complications (HR: 1.46; 95% CI: 1.18-1.79), and zoster without complications (HR: 1.66; 95% CI: 1.55-1.77). Kaplan-Meier curve analysis (log-rank p < 0.05) results indicated that the risk of HZ remained significantly higher in patients with COVID-19 compared with those without COVID-19. Finally, the higher risk of HZ in the COVID-19 cohort compared with that in the non-COVID-19 cohort remained consistent across subgroup analyses regardless of vaccine status, age, or sex. The risk of HZ within a 12-month follow-up period was significantly higher in patients who had recovered from COVID-19 compared with that in the control group. This result highlights the importance of carefully monitoring HZ in this population and suggests the potential benefit of the HZ vaccine for patients with COVID-19.

Discipline Area Score
Physician 6 / 7
Comments from MORE raters

Physician rater

Seems like a low attack rate for HZV. Th article is difficult to read. NNT?? Everybody over 50 SHOULD get the shot, anyway.

Physician rater

I have serious concerns about the design of this study. Although they do use propensity score matching to make the COVID and non-COVID groups comparable, they make a number of other decisions that could introduce bias: 1. they discard anyone that died within the first 30 days after COVID. This would be better handled using competing risk analysis; 2. one would think that the risk for immunosuppression and zoster reactivation might vary according to time after COVID infection, but the proportional hazards assumption doesn't allow for this. The finding that the risk of zoster continues to increase linearly after COVID seems really paradoxical; 3. the finding that the risk for zoster is similar between those who were vaccinated and those who were not is also paradoxical. There is a lack of specificity in this effect that is worrisome.

Physician rater

It is an interesting article for public health.
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