They have been joined by 19 charities to pen a letter arguing the medication is a matter of life or death for Britons with weakened immune systems, such as those with blood cancer or an organ transplant.They have been joined by 19 charities to pen a letter arguing the medication is a matter of life or death for Britons with weakened immune systems, such as those with blood cancer or an organ transplant.Read MoreHealth News | Mail Online