Reibun
、。、。

Throat and nasal membranes damaged by dry air become more vulnerable to cold viruses. It's essential to use heaters for cold prevention and humidifiers for dryness prevention.

Literal

Dry air [because-のせいで] damaged throat [and-や] nose [possessive-の] mucous-membranes [topic-は], cold [possessive-の] virus [subject-が] enter-[easy-やすく] become-[regret-てしまいます]. Heater [with-で] cold-countermeasure, humidifier [with-で] dryness-countermeasure [object-を] firmly carry-out [nominalizer-こと] [subject-が] essential [copula-です].

A health-advice passage using parallel structure: 暖房器具で寒さ対策、加湿器で乾燥対策 mirrors X で Y 対策 twice. 肝要 ('essential, crucial') is a formal kango word — 肝 'liver' + 要 'vital' — reflecting classical Chinese medical tradition. 入り込みやすくなってしまいます chains three auxiliaries: easy-to-enter + become + unfortunately.