Delta, a new coronavirus variant, was first identified in India in October 2020, and this variant was named B.1.617 by WHO and named with the Greek letter delta (delta) on May 31. The early symptoms of infection with the Delta strain are not obvious and do not differ significantly from the clinical symptoms caused by the previous strains, which are still the familiar symptoms of infection, such as fever, dry cough, malaise, etc. There is a subset of infected individuals who have no clinical symptoms in the early stages of the disease, i.e., those who are asymptomatic, although this subset of the population may develop clinical symptoms later in the course of the disease. The Delta strain has the following characteristics: 1. Significantly increased transmission capacity: twice the transmission capacity of other strains in the past, and more than 40% higher than the transmission capacity of the Alpha strain found in the UK; 2. Shortened incubation period or transmission interval: the virus is spreading at a faster rate, and even five or six generations in just 10 days from the previous situation; 3. High viral load: PCR testing of viral samples from infected patients The results showed that there was a significant increase in viral load. The Ct value of the patient was very low, and the lower the Ct value means the higher the viral load in the body, and the time needed for the patient’s nucleic acid to turn negative was prolonged. In addition, in the analysis of confirmed cases of Delta strain infection in China, according to previous studies, vaccinated cases had a shorter time from diagnosis to antibody production, a higher Ct value (the higher the Ct value, the lower the viral nucleic acid concentration) and a shorter hospital stay compared to unvaccinated individuals. Although there may still be some risk of infection after vaccination, the vaccine is clearly protective. Prevention and control of the delta strain is very important due to its significantly increased infectivity, rapid mutation and lack of typical clinical symptoms after infection. It is important to provide good personal protection and hygiene and to actively vaccinate against neo-crown, as vaccination is an effective measure to prevent the disease. Care should also be taken not to go to places contaminated with New Guan patients or the virus, to wear a mask properly when going out, to reduce contact with public parts, not to go to or minimize going to crowded places, to keep social distance, to wash hands and disinfect in time when going home, and to disinfect objects frequently touched at home.