Shingles risk after Covid boosters appears small and temporary, study finds

A large study from the University of Groningen in the Netherlands found a small, temporary uptick in shingles risk in the weeks after Covid-19 vaccination, with the largest increase seen after a third, or booster, dose of an mRNA vaccine.

The researchers analyzed electronic health records from more than two million people aged 12 and older who had received at least one Covid vaccine. They reported that shingles diagnosed within 28 days of vaccination rose by seven percent overall, and by 21 percent after the booster dose of an mRNA vaccine. Shingles, caused by the varicella-zoster virus, typically presents as a painful blistering rash.

The study analyzed vaccines by type, including mRNA versus vector vaccines, and by brand. For individuals who received two doses less than 28 days apart, it was difficult to determine which vaccine caused shingles, so only those with a consistent vaccination regimen were included in the type- and brand-specific analyses. The median age of participants was 51, with most between roughly 32 and 70. The two most common conditions were cardiovascular disease (25.7%) and chronic lung disease (16.3%). Pfizer/BioNTech accounted for 69.2% of all doses, Moderna for 18.6%.

The authors stressed that the observed link does not prove that vaccines cause shingles; the increase is small, temporary, and concentrated in certain subgroups. They noted that most shingles cases are treated in general practice and do not require hospitalization. The study also found a higher risk after vector-based vaccines among men of all ages, with a 38% increase, though the authors cautioned that these subgroup findings require further study.

Several related findings provide context. Hong Kong reported a sharp rise in hospitalizations for shingles soon after Pfizer/BioNTech vaccination. By contrast, a separate U.S. study using healthcare claims data found no increased risk after Covid vaccination and no higher risk than receipt of flu shots.

Separately, research has linked shingles with dementia risk in older adults. A prior Italian study of adults aged 50 and older hospitalized with shingles found a two-fold to seven-fold increase in early dementia within a year, with the greatest risk seen in those aged 50 to 65.

The study comes as U.S. health officials discuss potential labeling changes for Covid vaccines. Reports described the possibility of adding a black box warning—the strongest warning required on a drug’s labeling—but details remain under discussion.

In a related public debate, former U.K. health minister Lord Bethell wrote an opinion piece arguing that the Shingrix shingles vaccine could be a cost-effective dementia-prevention tool if offered widely on the NHS and possibly to younger ages. He described paying privately for a second dose and argued that expanding access could reduce dementia risk, citing studies suggesting vaccination might lower dementia rates. Public health experts said that while some studies hint at a link between shingles vaccination and reduced dementia risk, definitive evidence is lacking and more research is needed. The piece also highlighted concerns about NHS access to Shingrix and called for broader vaccination policy discussions.

The study’s authors and public health experts caution against drawing broad conclusions about vaccines and dementia. While the shingles vaccine remains an important preventive measure against painful disease, the potential protective effect against dementia, if proven, would require more robust evidence. Ongoing studies, including large NHS datasets, aim to clarify whether vaccination could influence long-term cognitive outcomes.