Delta virus belongs to a mutant strain of the new coronavirus, and current statistics show that a person infected with Delta virus can infect 5-9 people. The reasons for the high infectivity of Delta virus are mainly related to the fast replication speed, short incubation period, high load and strong adsorption of Delta virus: 1. The viral load is simply the amount of virus in the blood, compared with other new coronavirus strains, the viral load detected in delta virus-infected patients is significantly higher. The viral load detected in delta virus-infected patients is significantly higher compared to other NIV strains, which also means more infectious; 4. However, the spread of delta virus does not mean that the vaccine is ineffective. Vaccination with the new crown vaccine is still an effective means to fight against the virus infection, and the active ingredients in the vaccine can also reduce the possibility of deterioration of the disease development. Even though Delta virus is highly transmissible, there are still ways for humans to fight and defeat it.