What is the relationship between the Covid-19 vaccine and the shingles rash?


Eduardo Lopez Bran



Fortunately, we know very well the many benefits that vaccination offers against the Covid-19. Especially to reduce the severity of the disease caused by SARS-CoV-2 in people who, despite having been vaccinated, become reinfected with said disease. It is a great prevention tool for people with certain chronic health conditions.

However, the communication of some Adverse effects causes some concern in the population. That is what has happened with the recent cases of Herpes zoster who have attended dermatology consultations in recent months.

How to identify the relationship between herpes and vaccination

The marketing of drugs is always accompanied by the implementation of international pharmacovigilance programs that allow the detection of possible adverse effects thereof.

And vaccines are no strangers to these programs.

This has made it possible to collect effects after the administration of the vaccines, among which are the skin reactions that we will talk about in this article.

We can differentiate between local and immediate, such as those that occur at the injection site in the form of erythema, burning, etc. But there are also other generalized and delayed ones, among which some more frequent ones stand out, such as morbilliform rashes, rash in the form of spots and erythematous papules that converge and disappear in the same order in which they appeared. Cases of chilblain-like lesions on the fingers have also been described.

The case of shingles

Cases of herpes virus reactivation after Covid-19 infection have also been described. And the anti-vaccine movements have not missed the opportunity to generate fear in the population.

The most accepted theory is that they are due to lymphopenia (condition in which there is a lower than normal number of lymphocytes, a type of white blood cell, in the blood) caused by SARS-CoV2. This has been thought of because the latency of herpesviruses depends on T cell-dependent immunity.

However, this mechanism would not explain the reactivations after vaccination because in these cases there is no lymphopenia. Therefore, another probable hypothesis is that they may be due to immunomodulation processes, that is, changes in the functioning of the immune system due to alteration of the function of T lymphocytes.

In Spain, cases of herpes virus infection have been described in vaccinated patients with an incidence of 0.836 cases per 1,000 vaccinated people. 55% of the cases have occurred in women and the average age of the patients has been 66 years.

In the Dermatology Service of the Clinical Hospital of Madrid, some cases have been seen in which the lesions appear one or two days after the first or second dose. In some patients, the presence of chickenpox virus zoster and in others herpes simplex virus.

A common adverse effect of multiple vaccines

Shingles is caused by reactivation of latent varicella zoster virus infection. After the first contagion, it produces the clinical picture known as chickenpox. This contagion usually happens in childhood and normally such an infection resolves itself.

But once the condition is overcome, this type of infection becomes very common in adulthood and more than one in three people in the world population suffers from a symptomatic infection. Let us remember that the reactivation of herpetic infection frequently occurs spontaneously or after situations of stress, fever, exposure to ultraviolet radiation, immunosuppression…

Herpes is clinically characterized by vesicles or tiny reddened bags, associated with intense pain, hypersensitivity and irritation. In addition, they are usually preceded by previous manifestations of discomfort.

It can appear in any location but it is more common on the trunk and face. The lesions disappear in a few days and only require symptomatic treatment, usually with antivirals such as acyclovir, fanciclovir, valacyclovir or brivudine. 20% of the population suffers from herpes zoster in their life and it is more frequent in over 50 years.

Among the possible complications, the incidence of which increases with age, the most frequent is postherpetic neuralgia (a disorder that affects nerve fibers and the skin), which occurs in between 10 and 20% of cases, especially if early treatment is not instituted.

Mass vaccination campaigns have in some cases led to skin reactions that can cause concern in patients, such as the one we have discussed here. But so far we can say that they are usually mild and are not a contraindication to inoculate the vaccine or to receive second or third doses of it.

Furthermore, it should be noted that these reactions, both local and generalized, are not exclusive to vaccines against Covid-19 and they are also presented with others developed for different diseases. Most are of short duration and intensity, although there may be small variations on an individual basis.

Eduardo Lopez Bran. Professor of dermatology. School of Medicine. Complutense University of Madrid.

This article was originally published on The Conversation.

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