In allusion to the COVID-19 epidemic situation, the current key point to win the decisive victory is on how to improve the antibody prevalence, so as to achieve herd immunity and eventually eliminate the epidemic situation. Therefore, it is strongly recommended that an authoritative experimental conclusion should be given on whether the recovered patients with COVID-19 are infectivity or not. That is to say, those susceptible people who have not yet had the antibodies should be tested, in order to verify whether they would produce antibodies after close contact with the recovered patients who have had the antibodies. Of course, this is a feasible experiment. The implication that there should be a type of infectious vaccines against SARS-CoV-2, which is always around us and well within reach. In addition, it is pointed out that the state of balance where the viruses and the human immune system are opposed and can coexist is the environment they face for survival and proliferation, while the infectivity is the necessary condition. It is under such environment that the progenies of those original viruses would be just possible to be improved by human immune system, thereby evolve into the main part of the IgG antibodies. Since asymptomatic infected persons are now confirmed to transmit the viruses, so it is inferred that the Infectious Attenuated Live Vaccine against SARS-CoV-2 must be there too.