It appears to be. But the evidence is indirect. The basic genetic make up for the vaccine is the spike protein which is remarkably stable. My opinion (because God forbid I make an opinion without 16 peer reviewed journals but I am qualified to have an expert opinion) is that this is likely a natural evolution of the disease from less deadly to more virulent in accordance with most laws of virology. I do not think it changes the basic biology I just think a wild type is selected that is less likely to die out due to host death.
[I do not think it changes the basic biology I just think a wild type is selected that is less likely to die out due to host death.]