You need to read just four sentences from this Washington Post story to understand why the Delta variant of coronavirus is such a threat to the U.S. and the world.
[Before delta] Epidemiologists had hoped getting 70 or 80 percent of the population vaccinated, in combination with immunity from natural infections, would bring the virus under control. But a more contagious virus means the vaccination target has to be much higher, perhaps in the range of 90 percent.
Globally, that could take years. In the United States, the target may be impossible to reach anytime soon given the hardened vaccine resistance in a sizable fraction of the country, the fact that children under 12 remain ineligible and the persistent circulation of disinformation about vaccines and the pandemic.
Keep those statements in mind when you read about proactive governments testing the entire population of some cities or locking down large sections of a country. Those leaders are doing what it takes to keep the virus in check. Leaders of other countries carrying on as if nothing is happening are delusional.