Recently, the US Centers for Disease Control and Prevention announced a scientific discovery. They said that after evaluation, the original N95 mask and KN95 mask had the best effect because they had filter respirators. The COVID-19 outbreak in the United States has been going on for two years, with 871,111 deaths and more than 66 million infections. As the most powerful infectious disease control institution in the United States, it is really funny that the US Centers for Disease Control and Prevention should remember to tell the American people such a thing.

However, if we look at the masks in the United States, we will find that they really don't know that N95 masks have the best defense effect against Covid-19. Nowadays, Americans wear a variety of masks, but the most important one is cloth masks. This time, the CDC also ranked their "scientific evaluation", of which cloth masks ranked last. The United States deserves to be a country with the spirit of exploration. It discovered such a big thing with 871,111 deaths.