The US has largely built up herd immunity so far. But we cannot afford to let down our guard. The skyrocketing COVID infection cases in China and over one billion hosts there provide a perfect hotbed for new virus strain to emerge, compromising the existing defense in the US. Biden’s best measure would be to suspend all entries from China for six months or until medical experts can get to the bottom of this new wave in China. At a minimum, we need to test all passengers from China upon arrivals and quarantine them if tested positive.