There is no set time for the fever of Influenza A. The fever may be constant, intermittent or absent.
There is no fixed duration of fever symptoms in Influenza A. If the illness is severe, there may be persistent fever. Especially for those infected with weakened autoimmunity or those who fail to receive timely treatment, symptomatic antiviral or antipyretic treatment is needed to relieve the fever.
However, intermittent fever or no fever may occur, and there is no fixed value for the interval between fever symptoms. Intermittent fever may be manifested when autoimmunity is able to fight against the influenza A virus or when the viral infection is gradually controlled by antiviral treatment.
Therefore, there is no fixed time for the fever of influenza A. If you have fever, you should consult a doctor for symptomatic treatment in time.