Influenza is still able to spread outside of the flu season – just not as effectively. Non-seasonal outbreaks may still occur in more susceptible groups, such as in nursing homes. It has also been hypothesised that influenza is passed around outside the flu season by a subpopulation of asymptomatic people who are particularly good at transmitting the virus. This would mean that influenza would already be widely seeded in the population when the flu season arrived.