Delta (Delta/δ) variant strain is one of the most dominant virus variant strains in the current global New Crown epidemic, which is characterized by high transmission ability, rapid transmission and atypical onset symptoms. Current laboratory studies have shown that the Chinese biological New Crown vaccine is able to cross-neutralize all four typical variant strains, including the Delta strain, and Kexing has also seen significant results by conducting neutralization tests with different virus strains in sera from subjects vaccinated with Kexing vaccine; in other words, the domestic vaccine still has some protection against the Delta strain. It should be noted that since the Delta strain is a variant of the New Coronavirus, which reduces the level of neutralization of vaccine antibodies, there is still a chance of infection after vaccination with the New Coronavirus. In the analysis of confirmed cases of infection with the Delta variant strain in China, data showed that patients who received the neo-crown vaccine had a shorter time from diagnosis to positive antibody conversion, higher Ct values (the higher the Ct value, the lower the viral nucleic acid concentration), and shorter reported hospital stays compared to those who did not receive the vaccine. Therefore, although there is still a certain risk of infection after vaccination, the vaccine is still protective for patients after infection. Currently, major vaccine manufacturers across the country have begun research and production of vaccines for variant strains such as delta, and it is believed that more targeted vaccines will soon be available. With the recent emergence of the Delta virus, there are new concerns about the prevention and control of the epidemic and the ability of the vaccine to protect against it. Like this time in Nanjing and last time in Guangzhou, people have been infected after vaccination. But without the vaccine, the number of infections could be even higher, so we should do what we can to receive it. After vaccination, the vaccine is only our first line of defense against the epidemic. Daily life protection, such as disinfection and wearing masks, still needs attention.