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Complete protection against infection has long been hailed as the holy grail of vaccination. It might simply be unachievable.

The summer that was supposed to mark America’s independence from COVID-19 is instead drawing to a close with the U.S. more firmly under the tyranny of the virus, with deaths per day back up to where they were in March.

While experts say there certainly is more the federal government can do, they also say part of the challenge is that a segment of the American population is simply refusing to get the vaccine, allowing the virus to continue to spread.

The U.S. health care system is again buckling under the weight of a COVID-19 surge that has filled more than 100,000 hospital beds nationwide and forced some states to consider enacting "crisis standards of care" — a last resort plan for rationing medical care during a catastrophic event.

The recent spread of the highly contagious Delta variant has thrown back-to-school plans into disarray, temporarily driving tens of thousands of students back to virtual learning or pausing instruction altogether.

Cases are starting to fall in some hard-hit Southern states, but nearly half of Americans are not fully vaccinated, allowing the Delta variant to persist.

The delta variant is everywhere. Here's how well experts feel the vaccines and our immunity are working against it right now.

More than 180,000 children have caught COVID over the past month, but the risk of severe disease appears to still be rare.

Some vaccinated people who develop breakthrough cases of covid-19, the illness caused by the virus, are learning a mild case may not seem so mild to the person enduring the infection.

To prevent the next pandemic, scientists don’t need a definitive answer about the genesis of Covid-19. Regardless of how the coronavirus outbreak started, researchers say the world urgently needs to do more to prevent both lab leaks and so-called “spillover” infections from animals.

The U.S. is projected to see nearly 100,000 more COVID-19 deaths between now and Dec. 1, according to the nation’s most closely watched forecasting model. But health experts say that toll could be cut in half if nearly everyone wore a mask in public spaces.

An array of activists, scientists and politicians said Wednesday that the Biden administration’s inconclusive report on the origins of the coronavirus pandemic demonstrates the need for further probes, even if that leads the United States into delicate geopolitical territory.