Washington (AFP) - When epidemiologists talked about "flattening the curve," they probably didn't mean it this way: the US hit its peak coronavirus caseload in April, but since that time the graph has been on a seemingly unending plateau.
That's unlike several other hard-hit countries which have successfully pushed down their numbers of new cases, including Spain and Italy, which now have bell-shaped curves.
Experts say the prolonged nature of the US epidemic is the result of the cumulative impact of regional outbreaks, as the virus that started out primarily on the coasts and in major cities moves inward.
Layered on top of that are the effects of lifting lockdowns in parts of the country that are experiencing rising cases, as well as a lapse in compliance with social distancing guidelines because of economic hardship, and in some cases a belief that the threat is overstated.
"The US is a large country both in geography and population, and the virus is at very different stages in different parts of the country," Tom Frieden, a former director of the Centers for Disease Control and Prevention told AFP.
The US saw more than 35,000 new cases for several days in April. While that figure has declined, it has still been exceeding 20,000 regularly in recent days.
By contrast, Italy was regularly hitting more than 5,000 cases per day in March but is currently experiencing figures in the low hundreds.
"We did not act quickly and robustly enough to stop the virus spreading initially, and data indicate that it travelled from initial hotspots along major transport routes into other urban and rural areas," added Frieden, now CEO of the non-profit Resolve to Save Lives.
To wit: the East Coast states of New York, New Jersey and Massachusetts accounted for about 50 percent of all cases until about a month or so ago -- but now the geographic footprint of the US epidemic has shifted to the Midwest and southeast, including Florida.
- Still not enough testing -
Another key problem, said Jennifer Nuzzo, an epidemiologist at Johns Hopkins, is that the United States is still not doing enough testing, contact tracing and isolation.
After coming late to the testing party -- for reasons ranging from technical issues to regulatory hurdles -- the US has now conducted more COVID-19 tests than any other country.
It even has one of the highest per capita rates per country of 62 per 1,000 people, according to the website ourworldindata.org -- better than Germany (52 per 1,000) and South Korea (20 per 1,000).
But according to Nuzzo, these numbers are misleading, because "the amount of testing that a country should do should be scaled to the size of its epidemic.
"The United States has the largest epidemic in the world so obviously we need to do a lot more testing than any other country."
For Johns Hopkins, the more important metric is the positivity rate -- that is, out of all tests conducted, how many came back positive for COVID-19.
As of June 7, the United States had an average daily positivity rate of 14 percent, well above the World Health Organization guideline of 5 percent over two weeks before social distancing guidelines should be relaxed.
By contrast, Germany, which has tested far fewer people in relation to its population, has a positivity rate of 5 percent.
- Social behavior -
Even if testing were scaled up, carrying out tests in of itself does very little good without the next steps -- finding out who was exposed and then asking them to isolate.
Here also, too many US states are lagging woefully behind.
Texas, which is experiencing a surge in cases after relaxing its lockdown, is a case in point. The state targeted hiring a modest 4,000 tracers by June, but according to local reports is still more than a thousand shy of even that goal.
Opt-in app based efforts have also been slow to get off the ground.
Then there is the fact that some people are growing tired of lockdowns, while others don't have the economic luxury of being able to stay home for prolonged periods.
The government sent some 160 million Americans a single stimulus check of up to $1,200 back in April but it's not clear whether more will be forthcoming.
Still others, particularly in so-called red states under Republican leadership, have chafed under restrictions and mask-wearing guidelines that they see as an affront to their personal freedom.
"The US is kind of on the extreme of the individual liberty side," Sten Vermund, dean of the Yale School of Public Health, told AFP.
Part of this has to do with mixed messaging from Republican leaders, including President Donald Trump, said Nuzzo.
"We have had at the highest political level an assertion that this is a situation that's been overblown, and that maybe certain protective behaviors are not necessary," she said.
More recently, tens of thousands of people across the country have taken to the streets to protest the killing on an unarmed black man by police, risking coronavirus infection to demonstrate against the public health threat of racialized state violence.