Discussion:
Varicella-zona Virus reactivation in immunocompetent cases infected with Severe Acute Respiratoy Syndrome Coronavirus 2 (SARS-Cov2) has been published [4, 5]. This association can be explained by cytokine release and lymphopenia during the COVID-19 [6]. A fair number of Herpes zoster cases developing after the administration of mRNA and inactivated COVID-19 vaccines have been reported in the litterature [2, 3, 7, 8]. The majority of the cases developed after the first dose versus the second dose of the vaccine. However, reported cases of reactivation of VZV after viral vector COVID-19 vaccines were few [9].
Most commonly reported adverse effects of COVID-19 vaccine were short term, mild to moderate pain in injection site, fatigue, fever and headache, but other side effects remain unknown [10]. The short delay of onset after vaccination and the occurrence in immunocompetent patients suggests a strong link between COVID-19 vaccine and herpes zoster emergence. The exact mechanism remain unsolved, but it is possible that the VZV reactivation is one of the side effects of the novel vaccination. A case control study of Alhasawi A et al , enrolling 186 patients, showed that the COVID-19 vaccination had significant statistical association with herpes zoster (adjusted matched odds ratio=4.87, 95% confidence interval : 2.40 – 9.89,p <0.001) [11].
These vaccines don’t cause lymphompenia or cytokine release, but they can induce an immunomodulaion that may be responsible for herpes zoster [12]. Another theory is suggesting similarities with the immune reconstitution syndrome (IRS) wich is a paradoxical worsening of a pre-existing infection seen in immunocompromised HIV patients, following the initiation of antiretroviral therapy [13].
The ophtalmic division of the trigeminal nerve is the most involved branch in herpes zoster, while the maxillary nerve, the second division wich is affected in our case, is the least frequently affected and rarely causes ocular injury [14]. In the study of Psichogiou etal , there were two cases of herpes zoster of the second division of the trigeminal nerve following mRNA COVID-19 vaccine [13].