US officials had predicted that Omicron would be the variant to end the pandemic. However, varying degrees of pandemic lockdown measures are still being carried out in recent weeks, while the new variant in the Omicron family–BA.2 has continued to spread to more than 110 countries based on data from outbreak.info. To differentiate them better, BA.1 is used as a name to describe the original Omicron.  What is the pathogenicity and transmissibility of BA.2, and how do Covid vaccines and natural immunity hold up against this subvariant? To get clear answers, we turned to Dr. Yuhong Dong, expert in infectious diseases and antiviral drug development.  Where Is BA.2? Covid cases began to decline early February, and rise again slightly in the week of March 14. These infection waves took place largely in Asia, Europe, and the Pacific. In Europe, there were no large spikes, but increases mainly in France, United …