Maternal Influenza Vaccines are Not Associated with Increased Health Risks for Child

Women who are pregnant have a similar risk of contracting influenza as women who are not but run a greater risk of more serious complications and higher mortality.And in recent years, with strains such as H1N1 Influenza, the high transmission rate can increase the incidence rate.

Influenza vaccinations for expecting mothers can be a strategy to mitigate such concerns but fetal health concerns have been raised. A new study published in JAMA showed that pregnant women who get influenza vaccines were not associated with increased risks for adverse health events or conditions.

“In this population-based cohort study with mean follow-up duration of 3.6 years, maternal influenza vaccination during pregnancy was not significantly associated with an increased risk of adverse early childhood health outcomes,” the investigators wrote.

The investigators looked at The Atlee Database which contained demographic information, prenatal risk factors, diagnoses, and procedures for every birth 500g or greater and 20 weeks’ gestation or longer in Nova Scotia, Canada from October 1, 2010, to March 31, 2014. They looked at childhood outcomes that were immune-related, such as asthma, infections, non–immune-related such as neoplasms, sensory impairment, and nonspecific such such as urgent or inpatient health care utilization, and measured from emergency department and hospitalization databases.

“There was no significant association between influenza vaccination during pregnancy and pediatric asthma (incidence rate, 3.0 vs 2.5 per 1000 person-years; difference, 0.53 per 1000 person-years [95% CI, −0.15 to 1.21]; adjusted hazard ratio [HR], 1.22 [95%CI, 0.94 to 1.59]), neoplasms (0.32 vs0.26 per 1000 person-years; difference,0.06 per 1000 person years [95%CI, −0.16 to 0.28]; adjusted HR, 1.26 [95%CI, 0.57 to2.78]), or sensory impairment (0.80vs0.97 per1000 person years; difference, −0.17 per 1000 person-years [95%CI, −0.54 to 0.21]; adjusted HR, 0.82 [95% CI, 0.49 to 1.37]),” the authors reported.

In addition, exposure to influenza vaccination “in utero was not significantly associated with overall infections (incidence rate, 184.6 vs 179.1 per 1000 person years; difference, 5.44 per 1000 person-years [95%CI, 0.01 to10.9].”

In an accompanying editorial in JAMA, the authors discussed some of the challenges of maternal influenza vaccination including the lack of vaccination programs in low and middle income countries and that the reduced influenza season of 2020- 2021 may leave mothers with less maternal antibodies for protection.

“Efforts are needed now to encourage maternal influenza vaccination worldwide and to act on the compelling efficacy and safety data associated with adverse childhood health outcomes,” the authors concluded.