Vaccination reaction rate is unaltered by ambient temperature on the day

Minor reactions are often experienced following the human papillomavirus (HPV) vaccination and negative vaccination experiences may discourage individuals from seeking future vaccinations. Ambient temperature is suggested to be linked to reaction rates. Optimising immunisation programs requires understanding associations of temperature and reactions. To investigate a potential association between temperature and reactions, logistic regressions were performed on data obtained for a two-year period from a vaccine safety monitoring system for children (ages 10-15 years) who received the HPV vaccination (n = 20466) and from publicly available meteorological records in Australia. Reaction rate was 8.3% overall and higher with concomitant vaccination versus HPV alone (9.3% vs 7.8%, p=<0.001). Logistic regression found no relationship between reactions and maximal temperature on the day of vaccination (p = 0.581); controlling for concomitant vaccination, age and gender did not alter the temperature-reaction relationship (p = 0.851) but did identify concomitant vaccination as a significant predictor. Our results suggest immunisation programs must weigh the advantages of improved vaccination coverage resulting from concomitant vaccination against an increase in reaction rates and, importantly, can be safely administered across a range of temperatures.