Headaches with or without a fever can be a long-haul symptom of COVID-19. As per experts, headaches in the case of Omicron can be the body's inflammatory reaction as it fights off the virus. Headaches caused due to the Omicron variant also lasts for three days, even if you take painkillers regularly. More people seem to develop headaches as a long-haul symptom than fevers.
In an August 2021 review, researchers identified 55 long-term symptoms of COVID-19. They defined a long-term symptom as one persisting between 14 to 110 days after infection. Among the people in the 15 studies included in the review, more than 80 percent developed at least one long-term symptom, the most common being: fatigue (58 percent); headache (44 percent); poor concentration (27 percent); hair loss (25 percent); and shortness of breath (24 percent). Intermittent fever was reported in 11 percent of people.