McCarthy NL, et al. - Researchers here sought to examine deaths among young children with respect to their vaccination patterns. They recognized few deaths, despite this, results did not suggest a difference in risk of all-cause mortality among fully vaccinated vs undervaccinated children. Thus with regard to all-cause mortality, findings supported the safety of the currently recommended immunization schedule.

Methods

• The study was performed on children born January 1, 2004 through December 31, 2009, enrolled in the Vaccine Safety Datalink (VSD) from birth through 18 months of age.
• Vaccination patterns during the first 18 months of life among 8 vaccines were assessed, and deaths occurring between 19 and 48 months of age were identified.
• Children with complex chronic conditions, contraindications to vaccination, and deaths due to injuries, congenital anomalies, or diseases with onset prior to 19 months of age were excluded.
• Among children with different patterns of immunization, mortality rates were calculated.
• They assessed incidence rate ratios (IRR) using the Cox proportional hazards model for children vaccinated according to the schedule vs undervaccinated children, adjusting for outpatient healthcare utilization, influenza vaccination, sex, and VSD site.

Results

• In the study, among 312,388 children, 199,661 (64%) were vaccinated in accordance to the schedule, and 112,727 (36%) were delayed or not vaccinated for at least one vaccine dose.
• Researchers recognized 18 deaths eligible for analysis; 11 occurred in children following the schedule (2.28 per 100,000 person-years), and 7 occurred in undervaccinated children (2.57 per 100,000 person-years).
• They noticed no significant difference regarding mortality rates between children following the schedule and undervaccinated children when deaths with unknown causes were excluded (IRR = 1.29, 95% CI = 0.33–4.99), as well as when deaths with unknown causes were included(IRR = 0.84, 95% CI = 0.32–2.99).