UMEM Educational Pearls

Category: Pediatrics

Title: Does the height of fever matter in the era of vaccines?

Keywords: fever, temperature, infection (PubMed Search)

Posted: 6/21/2024 by Jenny Guyther, MD (Updated: 7/14/2024)
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Teaching has circulated that a temperature of 40 degrees Celsius or above (hyperpyrexia), was associated with a greater incidence of serious bacterial infection.  However, this teaching originated in a time prior to the availability of childhood vaccinations. In fact, the largest retrospective study to support this used data from 1966-1974.  

2565 WELL APPEARING patients between the ages of 61 days and their 18th birthday who presented to a single tertiary care pediatric emergency department with the chief complaint of fever were included.  The prevalence of serious bacterial infection was compared to the presence of hyperpyrexia, age, chronic conditions, gender and vaccination status.

Serious bacterial infections (SBIs) included: deep space infections, appendicitis, pneumonia, mastoiditis, lymphadenitis, acute bacterial rhinosinusitis, urinary tract infection, pyelonephritis, cholecystitis, tubo-ovarian abscess, septic arthritis, osteomyelitis, bacteremia or bacterial meningitis.

There was NO statistically significant association between hyperpyrexia and SBIs. Older age and make sex were associated with a higher risk of SBIs.

Bottom line: In well appearing children 61 days and older, having a temperature >/= to 40 degrees was not associated with serious bacterial infections.


Rachad S, Nickel D, Berry F, et al. Risk of serious bacterial infections in pediatric patients with hyperpyrexia. J Am Coll Emerg Physicians Open. 2024;5(2):e13135. Published 2024 Mar 13. doi:10.1002/emp2.13135