Flu Contagiousness
Cell to Cell
The Influenza virus replicates quickly
- Symptoms of flu begin, peak, and then decline over a period of approximately 10 days.6
The chart below shows how influenza virus levels — or titer values — build rapidly but then take many days to subside.
Viral load levels chart the course of illness and flu contagiousness7
A short replication cycle allows influenza virus to spread quickly, which is why early treatment is so important.
Person to Person
The Influenza virus spreads quickly
- Influenza virus shedding continues for 3-10 days after infection.2 Anyone who comes in contact with an affected individual during this time risks developing the disease
- School children transmit influenza for twice as long as adults (10 or more days),2 often infecting other children and adults
The diagram on the right illustrates the nature of flu contagiousness — from the initial patient who needs influenza treatment to those who come in contact with that person and may need treatment or postexposure prophylaxis.
Infected patients and their close contacts
- During seasonal influenza outbreaks, 20% to 50% of a community can be affected8
Stopping the momentum of viral replication can limit the spread of influenza infection.
Next topic: Influenza Diagnosis
