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Various national and international studies have examined the link between SARS-CoV-2 infection, COVID vaccination, and the development of systemic autoimmune diseases and other inflammatory conditions. The scientific evidence available points to a clear conclusion: SARS-CoV-2 infection itself is associated with a higher risk for autoimmune and inflammatory disorders, whereas vaccination has not been shown to significantly increase that risk at the population level.

“This is an important message to reassure patients because many people continue to wonder if the vaccine could trigger a rheumatic or other disease in them. According to the available scientific evidence, there is no link between the COVID-19 vaccine and rheumatic diseases, whereas there is a link between the infection itself and an increased risk of developing these types of conditions,” Rubén Queiro, MD, PhD, associate professor at the University of Oviedo and consultant rheumatologist at the Central University Hospital of Asturias, Oviedo, Spain, told El Médico Interactivo, part of the Medscape Professional Network.

In the field of dermatology, possible skin effects associated with both the infection and vaccination have also been studied. Alba Catalá, MD, dermatologist at the Hospital Clínic de Barcelona, Barcelona, Spain, and author of a doctoral thesis on this topic, explained that vaccine-related skin reactions have indeed been reported, although in the vast majority of cases they are mild and self-limiting.

“There are characteristic reactions, such as inflammatory patches at the injection site, which disappear within a few days. These are effects we had already seen with other mRNA [messenger RNA] vaccines,” she added. Cases of hives, vasculitis, or inflammatory rashes triggered after vaccination have also been reported, some potentially serious, though extremely rare.

Fear of Thrombosis

Catalá emphasized that, after millions of doses administered worldwide, these cases “are anecdotal and rare.” “At first, there was a lot of fear of thrombosis, myocarditis, or allergies, but large studies and meta-analyses have shown that we’re talking about exceptional numbers — just a few cases per million vaccinated people,” she stated.

The dermatologist insists that the benefits of vaccination far outweigh the potential risks: “COVID-19 infection itself can cause skin rashes, inflammatory reactions, autoimmune diseases, and even vasculitis. The risk associated with the virus is much higher than that of the vaccine.”

Furthermore, she noted that SARS-CoV-2 infection has also been linked to cardiovascular complications and thrombotic events. “It was much more likely to develop a blood clot associated with the infection than with vaccination,” she emphasized.

The data come, among other studies, from a national multicenter study coordinated by Spanish dermatologists, which compiled cases of patients who developed skin rashes following vaccination and whose cause could not be explained by other factors.

“Millions of people were vaccinated, and it was to be expected that some cases would arise. However, most reactions were mild, self-limiting, and responded well to topical or pharmacological treatments. Severe reactions were very rare,” explained Catalá.

Lupus Associated With COVID

Even in autoimmune conditions such as lupus, she added, more cases were observed in association with SARS-CoV-2 infection than with the vaccine itself. “We saw some cases of lupus following vaccination but also associated with the virus, and the number of reactions resulting from the infection was clearly higher.”

The specialist concluded that, at the population level, “there is no doubt about the benefit of vaccination in preventing severe illness and death.” Although there may be exceptional adverse reactions — as with any medication or vaccine — the risk of not getting vaccinated remains considerably higher.

Catalá declared having no conflict of interest.

This article was translated from El Médico Interactivo on Univadis.