Some patients reported a prodrome that consisted of fatigue, muscle pain, and a vague feeling of being unwell. (CIDRAP)

The illness generally begins with a prodrome of fever (>38°C), which is often high, sometimes associated with chills and rigors and sometimes accompanied by other symptoms including headache, malaise, and myalgias. (World Health Organization)

Symptomatic infection typically has a mild prodrome for 5–9 days before people seek medical attention, resulting in substantial opportunity for community transmission.6 (Public Health Research & Practice)