https://t.co/SoWDo6ownt The study also showed that the variant has a substantial transmissibility advantage beyond BA.2, which was already 30% more transmissible than BA.1, and reduced cross-immunity to BA.1 such that the people who had Omicron BA.1 infections (estimated to be at least 40% of Americans) may be susceptible to reinfections by this variant. “Indeed, the Omicron-specific vaccines that use the BA.1 spike structure, which are in clinical trials and due to read out in the next couple of months, may not fulfill their promise with a variant that carries such immune escape properties." The study also makes a relevant comparison between BA.2.12.1 and the BA.4 and BA.5 variants (which share the same spike protein sequence), which have become dominant in South Africa.
Their (BA.4 and BA.5) increase in transmissibility does not appear to be as much as BA2.12.1, but their immune escape, relative lack of cross-reactive immunity to BA.1 and some increase resistance to monoclonal antibodies is similar to BA2.12.1.
Unlike BA2.12.1, BA.4 and BA.5 have not shown enhanced entry to cells. The study also pointed out the fact that it is concerning that there is significant drop in protection ‘from hospitalization even with 3-shots from prior vaccine effectiveness (pre-Omicron) well above 90%.’ A recent report suggested with BA.1 the durability of that protection may be shorter.