Women are more likely to experience injection site and systemic reactions to flu shots, regardless of age or vaccine type, Canadian researchers say. 

Their meta-analysis shows that for every 1000 influenza vaccinations, an additional 115 cases of injection site reactions and 74 extra cases of systemic reactions could be expected in women versus men. 

The University of Montreal-led team reviewed 18 studies with more than 34,000 adults to assess sex differences in flu shot reactions, with participants divided into two age groups — 18-65 and over-65s. 

They analysed adverse event reports within seven days of vaccination, as well as other health outcomes up to four weeks later and any serious events reported during the study period from 2010 to 2018.