Why is the Spring Festival a high-risk stage of epidemic spread?

First, the Spring Festival is winter, and the temperature is low, which is an environment suitable for virus survival;

Second, there is a rush hour to go home during the Spring Festival, and most people work outside. Going home during the Spring Festival increases the risk of contact infection.

Third, come back for dinner during the Spring Festival. There are people in all kinds of environments, and no one knows who has been in contact with whom, so the risk is great.