 The H1N1 vaccine was initially in short supply and in the U.S. , the CDC recommended that initial doses should go to priority groups such as pregnant women , people who live with or care for babies under six months old , children six months to four years old and health @-@ care workers . In the UK , the NHS recommended vaccine priority go to people over six months old who were clinically at risk for seasonal flu , pregnant women and households of people with compromised immunity . 
