“After all, as viruses couldn’t live without a host, a dead host is a dead end for viruses. So, what’s the point of killing the host quicker?”

Research published in February in the science journal BMJ showed that people infected with the B.1.1.7 variant of the coronavirus, which was first identified in the United Kingdom, are more likely to die than people infected with the original strain. This scary news was surprising to some people, writes scientist and medical writer Shin Jie Yong, because a widely accepted evolutionary theory suggests that viruses require live hosts in order to replicate and survive. It didn’t seem to make sense that the coronavirus would evolve to become more lethal, because then it would just kill off its hosts.

“Ultimately, the law isn’t absolute,” Yong writes. “It sometimes applies but not always.”

Read on to learn about the alternate theory explaining the increased lethality of the new strain, and what it means for beating Covid-19:

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