I would never have imagined this battle with COVID would go on as long as it has.
No one thought this war with the Coronavirus would stretch out this long.
ーI would never have imagined this battle with COVID would go on as long as it has.
「コロナとの戦いがこんなに長く続くとは想像もしなかった」
I would never have imagined で「決して想像しなかった」
battle with COVID で「コロナとの戦い」
to go on で「続く」
as long as で「〜もの長い間」
ーNo one thought this war with the Coronavirus would stretch out this long.
「コロナとの戦いがこんなに長引くとは誰も思わなかった」
war with the Coronavirus で「コロナとの戦い」
to stretch out で「長引く」
ご参考まで！
I never thought the fight against COVID would last this long.
I never thought the fight against COVID would last this long.
I didn’t expect our battle with COVID to turn into such a long-term struggle.
Who knew the fight against COVID would be such a long haul?
I can’t believe this has turned into such a long battle with COVID.
「コロナとの戦いがこんなに長期戦になるとは（思っていなかった）」は、
驚き＝I never thought / I didn’t expect / I can’t believe
戦い＝the fight against / the battle with
長期戦＝last this long / a long-term struggle / a long haul
を組み合わせると自然です。
カナダ 
アメリカ合衆国 
