Safety concerns with human papilloma virus immunization in Japan: Analysis and evaluation of Nagoya City's surveillance data for adverse events.

The survey was self-reported and had a 43.3% response rate, so symptoms may have been missed or misclassified. Analyses did not include all respondents: age data were available for 29,846 women, and first vaccination time was available for 26,665. Vaccinated and unvaccinated women were not randomly assigned, and healthier women may have been more likely to be vaccinated, especially in older age groups. The observation period was shorter for vaccinated cases than for unvaccinated controls, which can bias symptom counts. The statistical models did not fit the data well because age and study period effects were not linear or similar between groups, and the authors called some results preliminary. Many symptoms and models were tested without adjusting for multiple comparisons. The paper did not establish causation; associations could reflect reporting, selection, or other factors.

Do not conclude that HPV vaccination causes memory impairment, dyscalculia, dyslexia, involuntary movement, walking disability, or sudden attack of muscle weakness. The paper reports associations from self-reported survey data, and the authors state that the models were preliminary and that causation was not established.