Generally women have a greater immune response to flu vaccinations as compared to men. However their immunity weakens as they age and their estrogen decline suggests a study. The study was published in the journal of 'npj Vaccines'. We need to consider tailoring vaccine formulations and dosages based on the sex of the vaccine recipient as well as their age said Sabra Klein the study's senior author. First the researchers evaluated immune responses to the 2009 H1N1 influenza vaccine among 145 human volunteers -- one group age 18-45 years the other of 65 and the olders. Analysing key markers of