A Cross-Sectional Study on Herpes Zoster Diagnosis in the Time of COVID-19

Amidst the COVID-19 pandemic, several published reports note concomitant cases of herpes zoster (HZ) infections in COVID-19 positive patients, suggesting a potential coexistence of the two viruses, or an increased incidence of HZ in this population (1-4). In order to investigate the credibility of this association and determine whether the COVID-19 pandemic has truly affected the overall incidence of HZ, we analyzed the University of California COVID Research Data Set (UC CORDS). This centralized, de-identified database provides access to health records for patients with COVID-19 PCR testing across ABSTRACT


INTRODUCTION
five UC medical institutions: Davis, Irvine, Los Angeles, San Diego and San Francisco (5). From March 1 to August 31, 2020, it contains patient demographics, medical history, medical visit type (including inpatient, outpatient, and telehealth), and COVID-19 status on 226,093 patients. Patients collected from the UC CORDS were divided into two subgroups, those with a diagnosis code for HZ before COVID test and those with HZ after COVID testing within two months, prior or subsequent, of each other, to assess whether one infection may indicate the development of the other.
To analyze whether there was an increase in the HZ condition rate during the pandemic, we compared the total number of HZ cases to the total number of medical visits during the same six-month time frame (March to August) in 2019 and 2020 using the general de-identified UC health data warehouse (UCHDW).
Statistical analysis was completed using chisquared tests to determine a significant relationship between those with or without HZ and COVID-19 infections.
To analyze whether there was an increase in the HZ condition rate during the pandemic, we compared the total number of HZ cases to the total number of medical visits during the same six-month time frame (March to August) in 2019 and 2020 using the general de-identified UC health data warehouse (UCHDW). Statistical analysis was completed using chisquared tests to determine a significant relationship between those with or without HZ and COVID-19 infections.
A total of 608 patients were diagnosed with HZ from March 1 to August 31, 2020; of which, 2.1% (n=13) tested positive and 97.9% (n=595) tested negative for COVID-19 (Table 1). When compared to the overall COVID-19 positive test rate of 3.9% in the UC CORDS, the incidence of COVID-19 was lower in patients with HZ (χ 2 = 4.9331, p=.0264). Among patients with an HZ diagnosis prior to COVID-19 testing, only one patient (0.3%) developed HZ within two months prior to COVID-19 diagnosis. Comparatively, among patients with a HZ diagnosis within two months subsequent to COVID-19 testing, only three patients (1.0%) tested positive; one of which was diagnosed with HZ on the same day as COVID-19.  Table 2). These results

RESULTS
demonstrate an HZ condition rate of 0.0026 in 2019 and 0.0021 in 2020 (χ 2 =90.6454, p<.00001), indicating a significant decrease. In this study we did not find evidence to substantiate an association between HZ diagnosis and COVID-19. Additionally, the data suggests that, during the COVID-19 pandemic, there has been no increase in medical visits for HZ in the UC medical system, both in person and by telehealth. Limitations include use of tertiary center data, lack of clinical details, such as HZ location or disease treatment, due to deidentified data, rapidly changing testing criteria and availability, and inability for longitudinal follow-up. We recognize the overall number of HZ cases may be lower due to less patients seeking medical care due to the pandemic, leading to an apparent negative correlation between HZ and COVID-19. Future studies with larger databases may help better assess the details of this relationship.
In this limited dataset, there was no evidence to substantiate an association between HZ and COVID-19 infection, nor was there an increase in the number of cases of HZ during the time of the COVID-19 pandemic.