Shingles risk rises slightly after Covid boosters, new study finds

A new Dutch study published in Drug Safety on December 11 found a small, temporary increase in the risk of shingles after Covid vaccination. The risk of developing herpes zoster within 28 days of vaccination rose by seven percent when all doses were combined and by 21 percent after the third, or booster, dose of an mRNA vaccine.

Researchers analyzed electronic health records from more than two million people aged 12 and older who had received at least one Covid vaccine. The median age was 51, with most participants around 32 to 73. The two most common health conditions were cardiovascular disease (25.7%) and chronic lung disease (16.3%). Most participants received two vaccine doses, and Pfizer/BioNTech accounted for 69.2% of doses, followed by Moderna at 18.6%. The study also looked at vaccines by type—mRNA versus vector—and by brand to try to identify patterns.

Among men of all ages, researchers found a significantly higher risk of shingles after receiving a vector-based vaccine, with a 38% increase. The authors noted that the booster-associated rise in shingles risk appears small and is likely limited to certain subgroups; most shingles cases are managed in primary care rather than requiring hospitalization.

Methodologically, the team conducted the analysis in three steps, including an overarching analysis of all vaccines, followed by type-based analyses (mRNA vs vector) and brand-based analyses. For two-dose regimens spaced less than 28 days apart, attribution was difficult, so only those with a consistent vaccination history were included in the brand analyses. The study also noted that findings do not prove vaccines cause shingles; they indicate a small, temporary association in some people.

Outside the study, reports surfaced that the U.S. Food and Drug Administration is weighing plans to place a black box warning at the top of Covid vaccine prescribing information. CNN cited anonymous sources describing the consideration, though no final decision was detailed.

Context from other research is mixed. A Hong Kong report noted a sharp rise in hospitalizations for shingles after Pfizer/BioNTech vaccination. In the United States, a separate study using healthcare claims data found no increased risk after Covid vaccination and concluded vaccination was not linked to a higher risk than flu shots.

Earlier research has linked shingles to dementia risk. A study in Italy of adults aged 50 and older hospitalized with herpes zoster reported an elevated risk of early dementia within a year for those with the severe form of the disease. Some researchers see a potential link between shingles prevention and cognitive outcomes, though evidence remains inconclusive and more research is needed.

Experts emphasize that the shingles-vaccine relation to dementia remains an area of active study, but vaccines remain a critical tool to prevent serious illness. The authors call for further research to clarify mechanisms and identify which populations might benefit from tailored strategies. In related commentary, Lord Bethell urged broader access to the shingles vaccine in the NHS, arguing it could play a role in dementia risk reduction, while public health advocates stress that lifestyle measures also play a major part in reducing dementia risk.