 The SARS-CoV-2-Armachron variant BA.5 quickly spread around the globe, replacing BA.1-BA.2 in many countries. It had unique amino acid substitutions in its spike protein which allowed it to evade neutralizing antibodies produced by vaccinations as well as increase its ACE2 receptor binding affinity. In a long-term experiment involving male Syrian hamsters, researchers evaluated the neutralizing antibody responses and efficacy against BA.5 challenge following primary vaccination with either AD26.COV2.S, Janssen, or BNT162B2, Pfizer BioNTech, followed by a homologous or heterologous booster with mRNA-1273, Moderna, or NVX-CoV2373, Novax. One high or low dose of AD26.COV2.S provided more durable immunity than two primary doses of BNT162B2, while the NVX-CoV2373 booster provided the strongest augmentation of immunity, reduction.