Health experts are warning that states have not met the federal guidelines for reopening, including aggressive testing and tracing, and a downward trajectory of documented cases in a 14-day period. Reopening risks setting off another wave of the pandemic and its effects will not be immediately known.

“It will be at least two to three weeks before we see an increase in the number of infections because it takes time for individuals to infect others and for them to display symptoms,” said data scientist Youyang Gu, whose coronavirus projection model is cited by the Centers for Disease Control and Prevention.

Lifting measures prematurely could lead to a rebound of the virus, putting the US in the “same boat that we were a few weeks ago,” when the number of infections skyrocketed daily, said Dr. Anthony Fauci, a member of the White House Coronavirus Task Force.

Calls to wear masks become a flashpoint

To slow the predicted spread of the virus, some cities are asking people to wear masks in public. But those guidelines have been met with resistance, leading to confrontations.

In Michigan, two incidents involving masks made headlines nationwide. In one, a man shot dead a Family Dollar security guard who argued with a woman after she refused to comply with a statewide order to wear masks inside shops, officials said. Police also arrested a man who allegedly wiped his nose on the sleeve of a Dollar Tree employee who asked him to wear a mask to shop.

Hundred of miles away, the city of Stillwater, Oklahoma, revoked an order requiring residents to wear face coverings inside buildings after workers received threats.

Steven Taylor, a clinical psychologist and author of “The Psychology of Pandemics,” said people tend to rebel when they’re told what to do, even when the measures are to protect them.

“People value their freedoms,” he said. “They may become distressed or indignant or morally outraged when people are trying to encroach on their freedoms.”

The virus is hitting hard in some vulnerable communities

As some people rebel against protective measures, the virus continues to hit hard in places where social distancing is not an option.

Thousands of inmates have tested positive for coronavirus in federal and state prisons — many of whom showed no symptoms. In Ohio, more than 20% of the people infected with coronavirus are prisoners. And in Colorado, the state’s largest outbreak is in a correctional facility.

Things are just as bad in nursing homes, where the population is especially vulnerable. In Louisiana, more than 30% of the state’s coronavirus deaths are from nursing homes and longterm care facilities. In New Hampshire, they make up nearly 80% of the cases while in Arkansas, almost half of all of the state’s cases are in prisons and nursing homes.

Officials in several states have called for more testing in correctional facilities and nursing homes.

“Nursing homes have been ground zero for Covid-19,” said Seema Verma, the administrator of the Centers for Medicare and Medicaid Services.

It’s taken a deadly toll on the black community

America has an inequality problem and the coronavirus crisis is making it worse.

The pandemic is leaving few people untouched, but the toll is far more deadly for African Americans, who are dying at higher numbers.

African Americans make up 13.4% of the American population. But counties with higher black populations account for more than half of all coronavirus cases and almost 60% of deaths, according to a new study.

Disparities, including access to health care, are likely to blame, researchers concluded.

“Structural factors including health care access, density of households, unemployment, pervasive discrimination and others drive these disparities,” researchers said. “Social conditions, structural racism, and other factors elevate risk for Covid-19 diagnoses and deaths in black communities.”

The study involved scientists from Emory and Johns Hopkins universities, the University of Mississippi Medical Center and Georgetown University.

Of the more than 3,100 counties researchers studied coronavirus cases from late January to mid-April, they found deaths were higher in disproportionally black rural and small metro counties.