Viruses evolves faster than humans dahil sa random mutations or recombinations that change occurs in the DNA and RNA sequence. Posibleng yun natsambahang exotic animal na kinaen nung pinaka first victim ng covid ay carrier na ng mixed strain ng virus galing sa human at virus strain galing sa species na yun or combo ng 2 strain virus from different species na nagawang maka adopt sa human cells kaya naging new strain na covid19 like ng nangyari sa H1N1 noon na combo ng human virus + bird virus nagawang maka adopt sa new cell host ng baboy = new strain na nagagawa din maka infect ng human.