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

Area of Science:

• Pediatrics
• Immunology
• Public Health

Background:

• Fever is a common post-vaccination reaction in infants.
• Understanding real-world fever incidence is crucial for parental guidance and healthcare providers.
• Japanese vaccination schedules and common vaccine combinations warrant specific investigation.

Purpose of the Study:

• To determine the actual frequency of fever following vaccinations in Japanese infants.
• To identify specific demographic, temporal, and vaccine-related factors associated with post-vaccination fever.

Main Methods:

• Utilized data from the Papatto Ikuji smartphone application, collecting vaccination and daily temperature records.
• Included 5690 vaccination events from 2563 infants and toddlers aged 2-23 months.
• Employed mixed-effect logistic regression to analyze factors linked to post-vaccination fever.

Main Results:

• Post-vaccination fever occurred most frequently in 3-month-old infants (14.0%).
• Higher fever rates were observed during summer (9.3%) compared to winter (6.3%).
• Combined administration of PCV13, Hib, and DPT-IPV vaccines showed a significantly higher fever incidence (16.8%) than other combinations.

Conclusions:

• Male sex, younger age (3 months), and specific vaccine combinations (PCV13 and DPT-IPV) are associated with increased fever risk.
• Summer vaccination season is linked to a higher frequency of post-vaccination fever.
• Real-world data from childcare applications provide valuable insights into vaccine reactions in infants.