ATAGI has endorsed use of Novavax’s COVID-19 vaccine as a booster when no other vaccine is suitable and tweaked its advice on AstraZeneca’s shot in an update for immunisation providers.

The committee previously suggested AstraZeneca’s vaccine, Vaxzevria, was a booster option for people who had it as a primary course but now recommends it as a booster “in those who have a medical contraindication to or who decline a booster dose of mRNA vaccine”.  

New research suggests an mRNA vaccine booster after a primary course of Vaxzevria leads to a 10-fold higher increase in anti-spike IgG antibodies than a third or fourth Vaxzevria shot, according to ATAGI’s update, published on Wednesday.   

“This is particularly important with Omicron becoming the dominant circulating SARS-CoV-2 variant, where higher antibody levels after the booster dose appear important for providing protection against Omicron.”