Transmission electron micrograph of parts of the norovirus pathogenBSIP SA/AlamyA global international trial of an mRNA vaccine against norovirus is getting underway with the aim of reducing the health burden caused by the infamous winter vomiting bug. The trial has been complicated by the emergence of a new norovirus strain that is causing soaring numbers of cases in parts of the world, including England.Unfortunately, one of the strains which is most prevalent isnt in that jab, says Patrick Moore at the UKs National Institute for Health and Care Research, who is leading the UK branch of the trial. The high cases are probably