Notably, unlike COH04S351-vaccinated animals, COH04S529-vaccinated animals had significantly reduced lung viral loads compared to COH04S1-vaccinated animals at day 4 following challenge with BA.1 (Fig. 3a, c), consistent with improved immediate viral control of BA.1 lower respiratory tract infection through the BA.1-specific vaccine adaptation. Here, CFB is linked to Recurrent lower respiratory tract infections.