The US FDA has refused to review Moderna's application for approval of the new mRNA flu vaccine mRNA-1010.[1][2][4] The reason is that the 40,000-person clinical trial did not include an adequate and well-controlled control group to reflect the best available standard of care in the US.[1][2] The study compared the new vaccine with the standard flu vaccine and found it to be slightly more effective in adults 50 and older.[2] The FDA said that Moderna did not use a more suitable vaccine recommended for seniors for people over 65, although it initially approved the study.[1][2] Moderna defends the study, saying the FDA had not previously raised concerns about the vaccine's safety or effectiveness.[1][4] The firm received positive feedback during the administration of President Biden.[2] The FDA may reconsider the application if Moderna changes it and resubmits it.[1] Moderna is awaiting a meeting with the authority for further instructions.[1]