Serious bacterial infection risk in recently immunized febrile infants in the emergency department

STUDY OBJECTIVES

Fever following immunizations is a common presenting chiefcomplaint among infants. The 2021 American Academy of Pediatrics (AAP) febrile infant clinical practice guidelines exclude recently immunized (RI) infants. This is a challenge for clinicians in the management of the febrile RI young infant. The objective of this study was to assess the prevalence of SBI in RI febrile young infants between 6 and 12 weeks of age.

METHODS

This was a retrospective chart review of infants 6-12 weeks who presented with a fever ≥38 °C to two U.S. military academic Emergency Departments over a four-year period. Infants were considered recently immunized (RI) if they had received immunizations in the preceding 72 h prior to evaluation and not recently immunized (NRI) if they had not received immunizations during this time period. The primary outcome was prevalence of serious bacterial infection (SBI) further delineated into invasive-bacterial infection (IBI) and non-invasive bacterial infection (non-IBI) based on culture and/or radiograph reports.

RESULTS

Of the 508 febrile infants identified, 114 had received recent immunizations in the preceding 72 h. The overall prevalence of SBI was 11.4% (95% CI = 8.9-14.6) in our study population. The prevalence of SBI in NRI infants was 13.7% (95% CI = 10.6-17.6) compared to 3.5% (95% CI = 1.1-9.3) in RI infants. The relative risk of SBI in the setting of recent immunizations was 0.3 (95% CI = 0.1-0.7). There were no cases of invasive-bacterial infections (IBI) in the RI group with all but one of the SBI being urinary tract infections (UTI). The single non-UTI was a case of pneumonia in an infant who presented with respiratory symptoms within 24 h of immunizations.

CONCLUSION

The risk of IBI (meningitis or bacteremia) in RI infants aged 6 to 12 weeks is low. Non-IBI within the first 24 h following immunization was significantly lower than in febrile NRI infants. UTIs remain a risk in the RI population and investigation with urinalysis and urine culture should be encouraged. Shared decision making with families guide a less invasive approach to the care of these children. Future research utilizing a large prospective multi-center data registry would aid in further defining the risk of both IBI and non-IBI among RI infants.

Early phase clinical trials with human immunodeficiency virus-1 and malaria vectored vaccines in The Gambia: frontline challenges in study design and implementation

Human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and malaria are among the most important infectious diseases in developing countries. Existing control strategies are unlikely to curtail these diseases in the absence of efficacious vaccines. Testing of HIV and malaria vaccines candidates start with early phase trials that are increasingly being conducted in developing countries where the burden of the diseases is high. Unique challenges, which affect planning and implementation of vaccine trials according to internationally accepted standards have thus been identified. In this review, we highlight specific challenges encountered during two early phase trials of novel HIV-1 and malaria vectored vaccine candidates conducted in The Gambia and how some of these issues were pragmatically addressed. We hope our experience will be useful for key study personnel involved in day-to-day running of similar clinical trials. It may also guide future design and implementation of vaccine trials in resource-constrained settings.