The reason why the epidemic struck again

The reasons for the recurrence of the epidemic may include the following:

1. The infectivity of the virus itself.

2. People's awareness of prevention and control has declined.

3. The pressure on external defense investment has increased.

4. Seasonal climate change.

5. The seasonality of the virus. Outside the tropics, many common respiratory viruses will reappear in some seasons.

6. Immune system factors. Insufficient adaptive immune response, weakened immunity and immune escape of human immune system will destroy or avoid the bactericidal characteristics of immune system and lead to reinfection.

It should be noted that there are many reasons for the recurrence of the epidemic, which require the joint efforts of the whole society to prevent and control it.