The number of people infected with Covid-19 in the United States exceeds 1 million.

on November 2th, 222, the public health colleges of three American universities, Harvard, Yale and Stanford, uploaded the research progress of American people's immune defense against Omicron in medRxiv.

The results show that by November 1th, 222, it is estimated that 94% of Americans have been infected with Covid-19 at least once. 97.8% of Americans have immunity to Covid-19; The study also warned that with the evolution of the virus and the continuous decline of immune antibodies, it is necessary to be alert to a new wave of COVID-19 infection.

It is reported that, as one of the signals of the widespread spread of the disease, the content of Covid-19 in the wastewater in the United States has risen again, and the content of Covid-19 in the wastewater is at the third highest level since the outbreak of Xinguan epidemic. According to expert analysis, the unsatisfactory vaccination of influenza and COVID-19 vaccine is an important reason for the rapid spread of the epidemic. In addition, the cold weather in the northern hemisphere makes people go out less, which leads to an increase in indoor contact opportunities and a decline in immunity.

Main research results

1. Immune protection and attenuation established by infection/vaccination.

For example, if you have been infected with Omicron mutant+enhanced vaccination, the effectiveness of prevention of severe illness is higher than 95%, and even at 5 weeks, the effectiveness of prevention of infection with Omicron is still above 7%. If vaccination is strengthened, the effectiveness of prevention of severe illness is about 76%, and the effectiveness of prevention of infection with Omicron is less than 2%.

2. Proportion of people with different immune status

The research model shows that in the United States, 7% of people are repeatedly infected, 55.7% are repeatedly infected and vaccinated, 2.4% are infected only once, and 29.1% are infected once and vaccinated. That is, 94.2% of Americans have been infected with Covid-19, and only 3.6% have been vaccinated and not infected.