The number of sub-variants (all in the Omicron lineage) has expanded massively in the past couple months, to the extent it's very difficult to keep track of them. One thing we know for sure is they are more adept at evading immunity conferred by prior infection and/or vaccines their predecessors. Unfortunately, it's difficult to do studies that account for the many variables in play. I agree that requiring masks indoors and on public transportation would help reduce transmission of COVID-19, flu, and other pathogens. But people rail against even simple measures.