Post-vaccination fever in infants: Real-world data analysis using a childcare mobile application

To evaluate the real-world frequency of post-vaccination fever in Japanese infants and to identify factors associated with fever.

Data on vaccination and daily body temperature were collected using the smartphone application Papatto Ikuji, used by caregivers to record data on their children's daily activities. Mixed-effect logistic regression analysis was conducted to evaluate factors associated with post-vaccination fever.

The study included 5690 vaccination events in 2563 infants and toddler aged 2-23 months. Post-vaccination fever was observed most frequently in infants aged 3 months (14.0 %), 4 months (11.6 %), and 12-23 months (9.8 %). Season of vaccination was also a significant factor, with higher fever frequency in summer (9.3 %; odds ratio (OR) 1.59, 95 % confidence interval (CI) 1.16-2.17) compared with winter (6.3 %). A higher fever frequency was observed when PCV13 (13-valent pneumococcal conjugate vaccine), Hib (Haemophilus influenzae type b), and DPT-IPV (Diphtheria, Pertussis, Tetanus, and Inactivated Poliovirus) were administered together (16.8 %; OR 15.40, 95 % CI 6.54-36.26) than vaccination without either of them (1.3 %).

The study identified male, age, vaccine combinations (PCV13 and DPT-IPV), and summer as factors associated with post-vaccination fever in Japanese infants using real-world data from a childcare application.