Most people are susceptible to dengue fever and are resistant to homozygous dengue virus after infection with dengue fever, but not to different serotypes of dengue virus. People at high risk for severe dengue fever include patients with secondary dengue infection, the elderly, children, pregnant women, and people with underlying diseases. Pregnant women who are infected with dengue fever, especially after the fever subsides, will show hemorrhage and shock manifestations, which are not detected in time and can easily progress to dengue hemorrhagic fever and dengue shock syndrome, and the mortality rate of pregnant women is higher.