Re: Vaccination against pandemic A/H1N1 2009 influenza in pregnancy and risk of fetal death: cohort study in Denmark
In spite of adjusting for confounding for many factors the other factor is maternal infections including TORCH (Toxoplasma, Rubella, Cytomegalous, Herpes simplex and other infections) that are known to cause congenital anomalies and foetal deaths. Antiphospholipid antibody syndrome, prematurity,asphyxias, Intrauterine growth retardation and Rh incompatibility are not excluded in the comorbidities even when these are potential confounders. The authors have agreed to this in the limitations and said, “Several factors need to be considered when interpreting our finding of a significantly decreased risk of stillbirth associated with vaccination against H1N1 influenza”. They also said, “Thus the result from this analysis should be viewed as hypothesis generating and needs investigation in other studies before any conclusions on protective effects are drawn”.
Another fact of the matter is that antigen of influenza vaccine is ever-changing and the vaccine has to be changed periodically, accordingly, so the nature and ill-effects of the vaccine will change as well.
Competing interests: No competing interests