置き換わる

Caution required:

新型コロナウィラスが感染力の強い変異株『デルタ株』に置き換わるなか、感染しにくいとされてきた子どもにも感染が広がっている。

While the coronavirus rearranges itself into its highly contagious Delta variant, children — who had not been affected much until now — are increasingly getting infected too.

As schools reopen after summer vacation, experts are advising caution.