A new Australian study has found that seniors who get the Shingrix® shingles vaccine face a dramatic spike in shingles cases shortly after the first dose.

Within just 21 days, shingles reports to GPs among those 65 and older increased 15-fold, according to findings presented at the 2025 Communicable Diseases and Immunisation Conference (CDIC) in Adelaide.

The study, conducted by researchers from the Murdoch Children’s Research Institute and Victoria’s Vaccine Safety Service, analyzed over a year’s worth of real-world medical data using two large-scale, independent datasets.

It found a 15-fold increase in shingles cases reported to general practitioners within 21 days after the first dose of Shingrix among older adults. A more modest increase in hospital-based shingles cases was also observed.

Despite the massively increased chance of being infected with shingles in the first three weeks post-vaccination, the vaccine shows some long-term protection—slashing shingles risk by 83% after two doses.

Lead researcher Dr. Aishwarya Shetty points to the vaccine’s immune-boosting ingredient—a bacterial endotoxin-based adjuvant—as a possible reason for the short-term immune dip that could allow the dormant virus to flare up in vulnerable patients.

Although still unpublished and under peer review, the study is already fueling renewed scrutiny of vaccine safety.

Dr. Shetty stressed that being upfront about short-term risks can actually strengthen public trust in vaccination.