BA.4 and BA.5 are 10 percent more contagious than their immediate predecessor, the BA.2 form of Omicron. BA.2.12 and BA.2.12.1 are 25 percent more contagious. Equally alarmingly, BA.4, BA.5, BA.2.12 and B.2.12.1 are quickly becoming dominant in their respective regions of origin just a couple months after BA.2 became dominant. BA.2 for its part out-competed and replaced its own parent, BA.1, just a few months after BA.1 became dominant.

In other words, major new subvariants seem to be coming at us faster and faster. In that sense, the virus might seem like it’s winning a genetic game of chance. Confronted with a semi-permeable barrier of antibodies from vaccines and past infection, the pathogen is becoming more transmissible.

Immune pressure “will increase the rate of selection of those more fit variants that are circulating already in the population,” Edwin Michael, an epidemiologist at the Center for Global Health Infectious Disease Research at the University of South Florida, told The Daily Beast. “This will result in cascades of new variants appearing and spreading in the host population more frequently.”