Public health specialists have blamed early missteps and delays for helping Covid-19 to spread undetected in the United States as the White House scrambled to justify its response to the epidemic following its criticisms of Beijing’s response.
A report published in the Journal of the American Medical Association on Monday warned that limiting diagnostic tests to a narrow group of people and problems with the test kits had left the US with “minimal diagnostic capacity during the first few weeks of the epidemic”.
“In the early stages, Covid-19 has spread beyond the nation’s ability to detect it,” they wrote.
The report said early Centres for Disease Control (CDC) test kits produced inconclusive or invalid results for Covid-19, the disease caused by the new coronavirus, because the negative control failed.
State laboratories also encountered difficulty verifying the results, said the report by Joshua Sharfstein from Johns Hopkins University, Scott Becker from the Association of Public Health Laboratories in Maryland and Michelle Mello from Stanford University.
The reasons for these technical problems were still under investigation.
“The CDC also initially limited access to testing to a narrow group of individuals with known exposure. The delayed discovery of a case of Covid-19 in California, followed quickly by evidence of community transmission in multiple states, revealed the shortcomings of this strategy,” the report said.
The woman infected in California had been refused a test by the CDC because she did not have travel history to China, where the outbreak began in December, and was not a close contact of someone who had been there.
She was tested and confirmed to have the disease one week later in the first known case of community transmission in the US, where there have been more than 700 confirmed cases.
Public health specialists and politicians in the US, including Senate minority leader Chuck Schumer and former Democratic presidential candidate Elizabeth Warren, have complained about inadequate access to diagnostic tests, restricted testing criteria and inconclusive results from CDC tests.
Experts have also warned that regulatory hurdles prevent laboratories from using their own tests to make clinical diagnoses without authorisation from the US Food and Drug Administration.
These criticisms prompted the CDC to expand its criteria last Wednesday to allow clinicians to exercise judgment about coronavirus testing, and the FDA in late February updated its policy to allow more laboratories to develop and use their own tests.
But the report warned that while “initial testing criteria were too narrow to monitor and control the spread of the disease, the sudden pivot to a far broader testing approach, even as capacity remains limited, may be an overcorrection”.
Widespread testing, including for patients with mild symptoms, could overwhelm the medical services that patients with more severe symptoms needed, they said.
The report also said that the FDA’s decision to limit initial approval to CDC tests “for the purpose of ensuring accurate surveillance testing” made clear the risks of this strategy, namely insufficient capacity and difficulties in scaling up quickly.
“Evidence suggests that containment of Covid-19 may depend on early case detection and contact tracing,” the report said.
The epidemic has spread to more than 100 countries since the first case was identified in Wuhan, which has recorded more cases that anywhere else.
The US government has criticised China’s early efforts to contain the disease and accused it of lacking transparency.
Last week Secretary of State Mike Pompeo blamed Beijing for inadequate information-sharing that put the US “behind the curve” when dealing with the epidemic.
But the White House has since found its own response coming under fire and vice-president Mike Pence, who is leading US efforts to tackle the outbreak, admitted last week that there were not enough diagnostic tests in the country to meet anticipated demand.
But on Tuesday Donald Trump sought to justify the handling of the situation, saying it was doing a “very good job” on diagnostic testing,
He said changes to the testing policies were “nobody’s fault”, and the White House insisted that up to 4 million tests would be available in the country by the end of this week.
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