Influenza vaccination during pregnancy does not harm the health of children years later

Influenza vaccination of pregnant mothers does not increase the risk of adversely affecting infant health, Canadian researchers found in a retrospective cohort study.

Pregnant mothers vaccinated against the flu gave birth to children in the first few years without an increased risk of developing immune-related outcomes such as asthma or non-immune-related outcomes such as sensory impairment. Deshayne B. Dr. Fel and colleagues at the East Ontario Institute Children’s Hospital in Otawa.

These vaccines were not significantly associated with infections, neoplasms, or medical use, the authors write. JAMA..

“In North America and many other international countries, we encourage all pregnant women to be vaccinated against the flu each year, but many are not,” Fel said. Today’s Med Page“Therefore, our motivation was to generate high-quality evidence that could contribute to a broader understanding of the long-term safety of influenza vaccination during pregnancy.”

Fel added that other studies have shown that the main reason many pregnant women are not vaccinated against the flu is “due to safety concerns.” Cited a previous study that found an association between maternal vaccination during the 2009 H1N1 influenza pandemic and increased risk of preterm birth and fetal death.

“It is imperative to recognize the safety concerns of mothers who are sympathetically considering parenteral injections during pregnancy. Currently, data on benefits and safety, including long-term outcomes of offspring, are convincing. “There is power,” said Dr. Manish Patel of the CDC and collaborators. Ancillary editorial..

Fel and colleagues found out about the effects on the foetation born after the mother was vaccinated and the health consequences of years after her resistance to the flu vaccine. Attempted to provide evidence of the safety of influenza vaccination.

Health data was obtained from the birth registry, which includes all births in Nova Scotia, Canada, from October 1, 2010 to March 31, 2014. Follow-up was completed on March 31, 2016, with an average follow-up of 3.6 years. The babies surveyed had to weigh more than 500 grams and be born at least 20 weeks gestation.

The main results of this population-based study included immune-related outcomes (such as infections and asthma) and non-immune-related outcomes (such as sensory impairment and neoplasms). Other outcomes were non-specific outcomes such as inpatient health care use, emergency visits, and emergency hospitalization. Negative controls were used to combat study bias involving unvaccinated pregnant mothers and their offspring.

This study included 28,255 children. Of these, 49% were girls and almost all were born over 37 weeks gestation. 36.2% of children were born to mothers who received the seasonal flu vaccine during pregnancy. Mothers vaccinated against the flu were over 35 years of age, more likely to have a pre-existing condition, and less likely to be current or former smokers or to live in low-income areas.

Influenza vaccination of mothers and development of childhood asthma (incidence per 1,000 person-years 3.0 vs 2.5, adjusted HR 1.22, 95% CI 0.94-1.59) or neoplasm development (incidence per 1,000 person 0.32 vs 0.26) -Year; aHR 1.26, 95% CI 0.57-2.78). Mother influenza vaccination was also not associated with sensory impairment (incidence 0.80 vs 0.97 per 1,000 person-years; aHR 0.82, 95% CI 0.49-1.37).

After adjustment, there was no association between maternal influenza vaccination and the development of early childhood infections (incidence 184.6 vs. 179.1 / 1,000 man-years; adjusted incidence ratio). [aIRR] 1.07, 95% CI 0.99-1.15).

“We evaluated a variety of children’s health outcomes, including immunity-related childhood health outcomes, such as the incidence of asthma, ear infections, respiratory infections, and other infections. No association was found with influenza vaccination during pregnancy, “said Fel.” This is not surprising, but it was very encouraging. “

In addition, there was no association between influenza vaccine and the use of health care services for emergency or inpatients (incidence rate 511.7 vs. 477.8 per 1,000 person-years; aIRR 1.05, 95% CI 0.99-1.16).

“The incidence of adverse outcomes was similar between vaccinated and unvaccinated mothers,” the editor wrote. “Efforts are now needed to encourage mothers to flu vaccination around the world and act on compelling efficacy and safety data.”

Fell and colleagues pointed out the limitations of the study, including the possibility of misclassified results due to unverified results. Outcome parameters were limited to emergency visits and hospitalizations, excluding less serious and unreported findings.