The United Kingdom approved its first protein-based COVID-19 vaccine, made by Novavax. The vaccine, called Nuvaxovid (generic name NVX-CoV2373), is the fifth COVID-19 vaccine authorized by the Medicines and Healthcare products Regulatory Agency (MHRA), the U.K.’s independent medicines regulator. Other COVID-19 vaccines authorized for use in the U.K. include those from Pfizer/BioNTech, Moderna,  Johnson & Johnson, and…