The study aimed to create a simple way to tell if infants 60 days or younger are unlikely to have serious bacterial infections. Through a prospective observational study conducted at 26 emergency departments, they got data from 1821 febrile infants. All infants were evaluated for serious bacterial infections (SBIs), including urinary tract infections (UTIs), bacteremia, and bacterial meningitis. The study came up with a “decision rule” and used 3 tests to determine who is at low risk for having an SBI, and those tests were: urinalysis, ANC (absolute neutrophil count), and procalcitonin levels. Those with a negative urinalysis, an ANC of <4090/µL, and serum procalcitonin level of <1.71 ng/mL were classified as “low risk”. 522 infants were classified as low risk, and only 1 had an SBI. So this decision rule to use those 3 tests to determine who is low risk showed high sensitivity. The study then validated this decision rule on another set of 913 infants, where it identified 497 infants as low risk, with only 2 having an SBI, resulting in a high sensitivity again, this time of 97.7%. They also found that among infants aged 29 to 60 days, the rule identified 776 as low risk, potentially sparing lumbar punctures for these low-risk patients. And the rule was effective in identifying patients with bacteremia and bacterial meningitis even after adjusting for different criteria for urinary tract infections. The study then went on to explore adjustments to the rule for easier application through emergency departments, while still maintaining similar accuracy. Overall, the authors’ findings suggest a simple and effective way to identify febrile infants at low risk for serious bacterial infections, which potentially reduces unnecessary procedures and treatments and hospitalizations.