The omicron subvariant is tuned to evade immunity, even from previous omicron infections.
The pattern has become all too familiar: A new version of the SARS-CoV-2 virus emerges and begins to dominate new Covid-19 cases, until it’s replaced by an even more contagious version of the virus.
This year, subvariants of the omicron variant of the virus have ruled cases in the US. The BA.1 subvariant started the omicron wave. Then in April, BA.2 formed the majority of cases. By May, BA.2.12.1 took over. Now BA.5 is in the lead, triggering a rise in hospitalizations across the country. It may be the most contagious version of the virus to date.
Why does this keep happening?