Prepare for US coronavirus case numbers to keep spiking - it's because we're finally testing

Prepare for US coronavirus case numbers to keep spiking - it's because we're finally testing
coronavirus test kit
  • The number of COVID-19 cases in the US surged from 4,000 at the beginning of the week to about 32,000 on Sunday.
  • The jump is in large part a reflection of increased testing - which means the number will probably continue to grow as the US's testing capacity keeps expanding.
  • Testing in the US has lagged severely behind compared to countries like China and South Korea.
  • Widespread testing and social isolation seem to be the two most effective ways to slow the coronavirus' spread, based on evidence from other countries.
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The number of COVID-19 cases in the US spiked from approximately 4,000 on Monday to more than 32,000 on Sunday.


Although the virus certainly continues to spread in the country, the gigantic jump also has a lot to do with increases in testing - you can't confirm or report cases without tests.

Testing capacity in the US is finally increasing noticeably after weeks of delays and mistakes.

As of Sunday, 191,541 coronavirus tests have been done in the US, according to the COVID Tracking Project, a test-tracking resource from two journalists at The Atlantic and the founder of a medical-data startup. (They noted that the figure could be incomplete because of different states' policies on reporting negative tests.) That's a huge jump from February 29, when only 472 tests had been run in the country. That was already more than a month after the US' first case was reported. On March 4, only 969 tests had been run, and by March 11, 7,617 had been done.

The slow ramp-up in testing was due in part to the Centers for Disease Control and Prevention's initial decision to create its own test, rather than using the WHO's. The agency shipped 90 test kits to approved state labs on February 6 and 7, but more than half of the tests turned out to be faulty and gave inconclusive results. The agency reported the flaw on February 10, but state labs were not given a fix for another 16 days. By the end of February, only three out of more than 100 approved state labs could run the test.


Because of the test shortages, the CDC at first issued strict guidelines about who qualified for tests: those with symptoms of COVID-19 who had recently traveled to China or had contact with someone who had a lab-confirmed case. The CDC expanded its criteria on February 27 to include patients with conditions so severe that they required hospitalization. But that still excluded many patients.

The guidelines were changed again in early March to allow anyone showing symptoms to get a test if their doctor thought it necessary.

As testing capacity continues to ramp up and more results come in, we can expect the number of cases in the US to continue to skyrocket.

Widespread testing is an important strategy for curbing the coronavirus' spread because it allows health officials to track and quarantine infected people, and also to trace others who an infected person had contact with.

So even though more widespread testing in the US means case numbers are reaching alarming levels, it is good overall that the US is catching more cases.


How to flatten the curve

Health experts are urging interventions that help "flatten the curve" - in other words, slow the virus' spread to reduce the number of people who are sick at the peak of the outbreak. That way, the country's healthcare system is less at risk of being overwhelmed.

coronavirus covid 19 spread healthcare system protective measures 2x1 flatten the curve

Evidence from countries like China, Italy, and South Korea so far suggests there are two effective strategies for fighting the coronavirus' spread: aggressive testing and social isolation.

Testing ensures that more sick people get treated and quarantined, and allows for contact tracing. If asymptomatic patients and those with mild cases don't get tested, some won't know they have COVID-19 and may continue spreading it. They also can't let their contacts know they've been exposed.

Social distancing, meanwhile, is necessary because studies so far suggest that on average, coronavirus patients pass the virus to 2.5 other people. Infected people can transmit the virus through coughing or spitting to others within 6 feet.

Many US states have announced social distancing measures - California Gov. Gavin Newsom has closed schools and told all residents to "stay at home" and only leave for essential services. New York Gov. Cuomo has mandated that nonessential businesses keep their workers at home starting Sunday evening.


Other states have similar measures: Ohio's state health department issued a "stay at home" order Sunday, and Iowa Gov. Kim Reynolds banned gatherings of 10 or more, closing bars, restaurants, and other facilities for at least two weeks.

You don't know who has the virus if you don't test

South Korea has been conducting between 12,000-15,000 coronavirus tests per day. The country has conducted more than 315,000 tests in total. (The chart below reflects the testing totals from Friday.)

COVID 19 testing per capita 2X1

The amount of testing a country conducts also influences its death rate - a calculation of the number of deaths out of the total number of cases. If more mild cases are caught, the death rate is lower.

As of Sunday, South Korea reported nearly 8,900 cases and 104 deaths. That's a death rate of around 1.2%. In Italy, where there are 5,476 deaths and 59,138 cases, the death rate is approximately 9.3%.

World Health Organization director-general Tedros Adhanom Ghebreyesus said last month that the global death rate of the coronavirus is about 3.4%.


In the US, New York upped its testing capacity this week - the state has now tested more than 32,000 people.

"We did 10,000 tests last night," New York Governor Andrew Cuomo wrote on Twitter on Friday. "New York has been very aggressive about increasing our number of tests."

New York has diagnosed more than 15,000 cases of coronavirus - a much higher number than any other state, and nearly half of all US diagnoses to date. In Washington state, where the second-highest number of coronavirus cases has been confirmed, labs have tallied nearly than 1,800 cases.

Aria Bendix, Rhea Mahbubani Kamal, and Hilary Brueck contributed reporting.