What Are The Symptoms Of 2024 Flu. Trivalent flu vaccines are formulated to protect against three flu viruses (an a(h1n1) virus, an a(h3n2) virus, and a b/victoria virus). The sheer scale of the u.s.

Get nhs advice on influenza (flu), including symptoms, how to treat it at home and when to seek medical advice. Tiredness or feeling run down.