If a woman has a flu shot while pregnant the chances of her baby getting flu or being admitted to hospital with a respiratory infection are significantly lower, especially during their first six months after being born, researchers wrote in an article published in Archives of Pediatrics & Adolescent Medicine.
Young children and especially babies have a higher risk of influenza complications. However, you cannot vaccinated a baby during their first six months.
The authors wrote:
Influenza virus infection in infants is generally more frequent among those aged 6 to 12 months than in the first six months of life, potentially owing to the protection conferred by maternal influenza antibodies acquired transplacentally or through breastfeeding. However, during severe influenza seasons, morbidity and mortality rates among infants younger than 6 months have been reported to exceed those of older infants.
Angelia A. Eick, Ph.D., Armed Forces Health Surveillance Center, Silver Spring, Md, and at the time of the study of Johns Hopkins Bloomberg School of Public Health, Baltimore, and team carried out a study on Navajo and White Mountain Apache Indian reservations – two areas with a higher incidence of severe respiratory infections among children than in the general population.
1,169 women had completed questionnaires about their vaccinations, vaccinations of all family members, and flu risk factors – all the women had had babies during one of three influenza seasons. 1,160 mothers and 1,160 of their babies gave blood samples and were checked for the presence of flu antibodies. At the end of the flu season the mothers completed another questionnaire – the researchers conducted surveillance, monitoring flu-like illnesses.
17% (193) of the infants were admitted to hospital for flu-like illness, while 36% (412) only had an outpatient visit for a respiratory problem. 48% (555) were symptom-free and did not seek medical help.
The investigators found that babies whose mothers had been vaccinated against flu during pregnancy had a 41% lower chance of developing laboratory-confirmed flu virus infection and were 39% less likely to have to be admitted to hospital because of a flu-like illness. Blood samples showed that the babies whose mothers had been vaccinated had higher levels of influenza antibodies than the babies of unvaccinated mothers.
The authors concluded:
Although influenza vaccination is recommended for pregnant women to reduce their risk of influenza complications, these findings provide support for the added benefit of protecting infants from influenza virus infection up to six months, the period when infants are not eligible for influenza vaccination but are at highest risk of severe influenza illness. These findings are particularly relevant with the emergence of 2009 pandemic influenza A (H1N1) virus, which had a substantial impact on pregnant women and high hospitalization rates among young infants.
Justin R. Ortiz, M.D., and Kathleen M. Neuzil, M.D., M.P.H., of PATH and the University of Washington, Seattle, wrote in an accompanying editorial:
The burden of influenza among pregnant women, the excellent safety profile of the vaccine and the reliable immunogenicity of trivalent inactivated influenza vaccine in this group support a recommendation that all pregnant women receive influenza vaccine to decrease complications of influenza disease during their pregnancies.
While the burden of influenza is not as well characterized in many tropical and developing countries, available evidence, including evidence from the recent H1N1 pandemic, supports that pregnant women are at high risk for influenza-related morbidity.
The additional benefits of maternal influenza vaccination to the newborn, as demonstrated in the Bangladesh and White Mountain and Apache Navajo communities, should catalyze efforts to improve vaccination rates in countries with existing maternal immunization recommendations. Likewise, these data should encourage the adoption of vaccination guidelines in countries without such recommendations. Maternal influenza vaccination targets two high-risk groups with one vaccine dose – we can’t afford not to act.
Angelia A. Eick, PhD; Timothy M. Uyeki, MD, MPH, MPP; Alexander Klimov, PhD; Henrietta Hall, MS; Raymond Reid, MD; Mathuram Santosham, MD; Katherine L. O’Brien, MD, MPH
Arch Pediatr Adolesc Med. Published online October 4, 2010. doi:10.1001/archpediatrics.2010.192
Written by Christian Nordqvist