Viruses can actually tolerate and survive in freezing cold temperatures so freezing cold temperatures will not kill viruses.
But in science class years ago I remember learning that if the viruses are exposed to freezing temperatures and then thaws out and then freezes again then the viruses are more likely to be killed by the frozen and thaw process.
It's more that heat actually kills bacteria and viruses if the viruses or bacteria are heated to 165 to 212 F degrees since viruses and bacteria cannot survive in really hot temperatures.