The first and second peak periods in COVID-19.

The first peak period in COVID-19 refers to the most serious period of the epidemic, that is, the initial period of the epidemic. At the initial stage of COVID-19 epidemic, many countries and regions experienced large-scale infection and spread, and medical resources were scarce, which seriously affected social life and economic operation. Countries have taken blockade measures and prevention and control measures to control the spread of the epidemic. The second peak period in COVID-19 refers to the second wave of outbreak after the epidemic has been initially controlled. Due to the differences in transmission characteristics and population immunity in COVID-19, the second peak may appear within a few months after the first peak. The severity of the second peak period may be different due to regional, prevention and control measures, crowd behavior and other factors. It should be noted that there is no completely effective treatment and vaccine for COVID-19 at present, so it is still very important to prevent and control the epidemic. During the first and second peak periods, the public should actively take health prevention and control measures, including wearing masks, washing hands frequently and keeping social distance to reduce the risk of virus transmission.