According to a new study published online as a medRxiv preprint, giving a COVID-19 vaccine and a seasonal flu vaccine at the same time appears to be safe and effective.

This is the first study to investigate how people react to both vaccines given at the same time. The Novavax vaccine - NVX-CoV2373 – has shown 89.8% efficacy in an ongoing phase 3 trial. When a group of 431 volunteers from the same study was administered an influenza vaccine at the same time, the efficacy slightly declined to 87.5%. Study co-author Raja Rajaram stated that the findings present an opportunity for concomitant vaccination, which may facilitate higher vaccination rates and provide protection against both the viruses… (Medscape)