(HealthDay News) – Simultaneous vaccination with trivalent inactivated influenza vaccine (TIV) and 13-valent pneumococcal vaccine (PCV13) is associated with increased risk of fever compared with receipt of either vaccine alone, according to a study published online Jan. 6 in JAMA Pediatrics.

Melissa S. Stockwell, MD, MPH, from Columbia University in New York City, and colleagues conducted a prospective observational cohort study involving 530 parents of children aged 6–23 months. Parents were texted on the night of vaccination and for seven days to report their child’s temperature; the rate of fever (temperature ≥38 degrees Celsius) on Days 0–1 was assessed.

The researchers found that children receiving TIV and PCV13 simultaneously had significantly higher rates of fever (37.6%) on Days 0–1 than those receiving only TIV (7.5%; adjusted relative risk, 2.69) or PCV13 (9.5%; adjusted relative risk, 2.67). For children receiving TIV and PCV13 simultaneously vs. TIV alone, the excess risk of fever after vaccination was 20 per 100 vaccinations, while the excess was 23 per 100 vaccinations compared with PCV13 alone. Across groups, similar fever rates were seen on days two to seven.

“Future studies could address the potential benefits and risks of administering TIV and PCV13 on different days or the effect of prophylactic antipyretics on vaccine-specific immune responses in patients for whom fever should be avoided for medical reasons,” the authors write.

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