https://store.joebiden.com/truth-over-flies-fly-swatter/

Brain fog ものわすれ

For Mirabai Nicholson-McKellar, Covid-19 brought an onslaught of symptoms from chest pains to an 11-day migraine, three positive test results, and a period in hospital.

Onslaught 猛攻撃

 I am unable to think clearly enough to [do] anything,” says Nicholson-McKellar, adding that the experience would be better described as cognitive impairment.

Impairment 低下　悪化

One difficulty in tackling “brain fog” is that the term itself is hazy.

Hazy 不明確

https://www.theguardian.com/world/2020/oct/09/brain-fog-the-people-struggling-to-think-clearly-months-after-covid