In its 24 years on Nasdaq Novavax has been through many ups and downs, and despite burning through $1.3bn of cash it has not achieved much of note. Today this record was maintained as its RSV vaccine Resvax bombed in its second phase III study – this time in pregnant women, examining prevention of the virus’s spread from mother to child. The trial, Prepare, failed its primary endpoint of cutting the incidence of medically significant RSV lower respiratory tract infection during the first 90 days of an infant’s life. In 2016 the vaccine failed a bigger study, which had tested it in prevention of moderate to severe RSV-associated lower respiratory tract disease. Apart from that negative precedent, the less than stellar mid-stage data in mother-to-child transmission and the fact that RSV remains a highly intractable though highly prevalent seasonal disease should have given pause. Nevertheless, Novavax’s valuation stood at $800m going into the Prepare result, before this morning’s 67% crash. There is nothing to suggest that the towel will be thrown in, however: exploratory endpoints and post hoc analyses from Prepare were enough for Novavax to hail Resvax as “the first RSV vaccine to show phase III efficacy”.