New studies suggest that BA.4 and BA.5, currently sweeping the U.S. and countries around the globe, have a growth advantage over BA.2 similar to the growth advantage BA.2 had over BA.1. Thus, the latest dominant COVID subvariants have a reproductive rate of around 18.6, tying or surpassing measles, the world’s most infectious viral disease, according to Esterman.

https://fortune.com/well/2022/07/09/can-you-get-covid-outside-outdoors-omicron-ba5-ba4/