Published: 20-09-2016 08:36 | Updated: 06-10-2016 11:18

Swine flu jab harmless to unborn babies

The swine flu vaccine, when administered to pregnant women, caused neither fetal injury nor infant death, writes Karolinska Institutet professor Johan F Ludvigsson an opinion piece in Tuesday’s Dagens Nyheter in conjunction with the publication of his research findings in The Annals of Internal Medicine.

Jonas F Ludvigsson is a professor at Karolinska Institutet and led this large-scale study on the swine flu vaccine Pandremix and its effects on fetal development. The study, which is the third and final part of a seven-year project, included over 40,000 mothers who were given the flu jab while pregnant. His results show that the vaccine did not increase the risk of child deformity, not even if given in the early stages of pregnancy.

Earlier studies have, however, shown that pregnant women often suffer more acutely from influenza than others. A major Norwegian study has also shown that the risk of stillbirth was twice as high as normal if the mother contracted swine flu while pregnant. This, writes Professor Ludvigsson, gives good cause to vaccinate pregnant women.

He is also convinced that this knowledge is valuable for the future, especially given the current concerns over the Zika virus, which is associated with microcephaly, the underdevelopment of the brain and head, in babies. If a Zika vaccine becomes available, it can be worth knowing how previous national vaccination programmes have affected pregnant women and their unborn babies.


Risk for Congenital Malformation With H1N1 Influenza Vaccine. A Cohort Study With Sibling Analysis
Jonas F. Ludvigsson, MD, PhD; Peter Ström, MSc; Cecilia Lundholm, MSc; Sven Cnattingius, MD, PhD; Anders Ekbom, MD, PhD; Åke Örtqvist, MD, PhD; Nils Feltelius, MD, PhD; Fredrik Granath, PhD; and Olof Stephansson, MD, PhD
Annals of Internal Medicine, online 20 September 2016, doi:10.7326/M16-0139