This is healthy. The only people that should complain about virus mutation are pharma companies expecting to make windfall on vaccines.
Usually when a virus mutates it does so by trading off another feature which could even be less-morbidity. Humans have been living with and are, in fact, comprised of virus DNA as we incorporate them into our genetics.
"No lethal pandemic lasts forever. The 1918 flu, for example, crisscrossed the globe and claimed tens of millions of lives, yet by 1920, the virus that caused it had become significantly less deadly, causing only ordinary seasonal flu."