I read that the NVAX booster is approved only as a first booster. I'm assuming you have received 1-2 boosters already EDIT: Link to the PR https://ir.novavax.com/U-S-Centers-for-Disease-Control-and-Prevention-Recommends-Novavax-COVID-19-Vaccine,-Adjuvanted-as-a-Booster-in-Adults The FDA has granted emergency use authorization for the Novavax COVID-19 Vaccine, Adjuvanted as a first booster in adults aged 18 and older, and as a two-dose primary series in adults aged 18 and older and in adolescents aged 12 through 17.