Vaccination has proved difficult as there are so many viruses involved and they mutate rapidly.

Their world was in free fall, mutating rapidly and unpredictably.

If this was indeed true and statistically relevant than all of Asia would be mutating rapidly.

They are highly toxic, and the virus, which mutates rapidly, eventually catches on to the deception.

The flu virus mutates very easily and rapidly, which is why we need to get flu shots every year.

He appears at the end of the novel as a rapidly mutating monster before he is destroyed.

But the virus mutates rapidly, and migratory birds do spread the disease.

Their odds of success against rapidly mutating viruses in the real world seemed small.

Flu viruses mutate rapidly, and usually they get weaker as they change, not stronger.

In two of the fatal cases, the virus rapidly mutated to become Tamiflu resistant and overwhelm the body.