The May Day holiday just passed, and major tourist attractions across the country were crowded with people. Although the population is dense, due to the warming weather, there are not many people wearing masks. Many people are worried that such close contact, coupled with the emergence of new strains, will lead to a re infection? On this issue, a reporter from Science and Technology Daily interviewed relevant experts. Neutralizing antibodies are still effective and the risk of secondary infection is relatively low. "From monitoring data, there is a trend of increasing cases nationwide, but there has been no large-scale outbreak," Wang Guiqiang, director of the Infectious Diseases Department at Peking University First Hospital, said in an interview with Science and Technology Daily on May 7th. Previously, the data released by the Chinese Center for Disease Control and Prevention showed that China had newly detected 12 local focus mutants such as XBB. 1.16. In this regard, Li Dong, chief physician of the Infectious General Department of Beijing You'an Hospital affiliated to Capital Medical University, said that the XBB.1.16 mutant is one of the recombinant strains of COVID-19, which has more mutation sites than the previous strains, making it more immune escape ability and transmissibility. China has previously found that antibody levels will decrease after 3-6 months of vaccination through antibody monitoring. However, after the last round of epidemic, not many people have been infected with COVID-19 for the second time, mainly because they were infected with the Omicron virus strain after vaccination, so the antibody level in the body will be higher and the protection period will be longer. "So for people who have been infected with COVID-19, the antibody in their bodies is still at a high level, and the risk of secondary infection is relatively low at present." Li Dong once said, but for the elderly and people with low immunity who have been infected for more than half a year since the last time, the risk of secondary infection will still increase, because the resistance of these people will decline faster, Especially in the face of XBB.1.16, a virus strain with strong immune escape ability. Wang Guiqiang also stated that the risk of secondary infection with the same virus strain is relatively low. However, the elderly and those with underlying diseases have weaker immune functions and lower levels of antibodies produced. Whether facing new variants or the risk of secondary infection, they are the population that needs to be focused on. These people should also complete vaccination to reduce the incidence of severe infections. Therefore, experts emphasize that although personnel mobility increases the risk of virus transmission, it is more targeted at the "non positive" population, which should pay special attention to protection. Even though the symptoms of "secondary infection" are mild, at present, according to the monitoring data of COVID-19 variants in China, the local cases are still dominated by BA. 5.2 and BF. 7 and their sub branches. From a dynamic perspective, XBB and sub branches are growing rapidly. Recently, XBB variants have occupied absolute advantage in imported cases, and the proportion of XBB variants in local cases has increased significantly. However, there are currently no reports of increased severe hospital admissions and deaths due to infection with XBB.1.16. Compared with other branches of Omicronia, there have been no reports of increased disease severity. Although there are reports that XBB.1.16 has increased the incidence of conjunctivitis, will this strain cause conjunctivitis due to other viruses such as adenoviruses, influenza viruses, and enteroviruses