The German Robert Koch Institute (RKI) now recommends antigen testing to supplement existing molecular polymerase chain reaction (PCR) tests, which have become the standard for the assessment of active infections, but which have also suffered from shortages because the pandemic has overwhelmed laboratories and exceeded the production capacity of manufacturers.
PCR tests detect genetic material in the virus while antigenic tests detect proteins on the surface of the virus, although both are intended to detect active infections. Another type of test, for antibodies the body makes in response to an infection, can help determine if someone has had COVID-19 in the past.
Like PCR testing, antigen testing requires an uncomfortable nasal swab. They can also produce more “false negatives”, leading some experts to recommend that they be used only in a pinch.
Still, the alarming rise in new infections around the world is causing health officials to desperately seek more options as the winter flu season approaches.
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The World Health Organization (WHO) reported more than two million new cases last week, bringing the global total to 37 million, with more than one million deaths from COVID-19.
“These point-of-care tests could make a big difference,” said Gerard Krause, director of the epidemiology department at the German Helmholtz Infection Research Center.
No test, no theft
Krause said low-priority patients – those without symptoms – could initially be tested with antigen tests, leaving PCR tests more accurate for those showing signs of the disease.
Antigen testing has already gained ground in the travel industry. Italian airline Alitalia offers Rome-Milan flights exclusively for passengers who test negative and German Lufthansa has announced similar test plans.
But the vast scale of the pandemic has strained countries’ ability to test all of their citizens, making it difficult to fully track the winding pathways of infection and prevent a resurgence.
In the United States, for example, the use of automated PCR machines during the summer left many patients frustrated as they waited for results for a week or more.
Testing in Europe also suffered from problems.
France performs over a million tests per week, but its free-to-all test policy has resulted in long queues and delays in results, prompting French researchers to come up with a test that they say may produce results in 40 minutes without using a swab.
Italy performs between 800,000 and 840,000 tests per week, more than double April’s levels, according to the health ministry. But a government adviser, University of Padua microbiology professor Andrea Crisanti, said the country needs two million tests per week to truly bring the virus under control.
In the Netherlands, where infection rates are among the highest in Europe, the government is working to expand weekly testing and laboratory capacity to 385,000 tests by next week, up from 280,000 currently. The goal is nearly half a million tests per week in December and just under 600,000 in February.
But some people have been waiting for days for a test. Authorities blame the overwhelming demand of those without clear symptoms to clog the system.
In response, rapid antigen testing has been restricted to health workers and teachers, while others are placed on a waiting list.
The various issues highlight a conundrum for governments: how to get people back to work while quickly tracing the virus through the population – without running out of supplies.
Siemens Healthineers, which announced on Wednesday the launch of a rapid antigen test kit in Europe that can provide a result in 15 minutes, said the volumes of these diagnostic tests currently released around the world are “at the limit.” of what manufacturers can provide.
Competitors, notably Abbott Laboratories and Becton Dickinson, are also offering numerous COVID-19 diagnostic tests, and more and more companies are joining the race.
Swiss diagnostics maker Roche on Tuesday announced plans to launch a new antigen test by the end of the year. Its fully automated systems can deliver a result in 18 minutes and a single lab machine can process 300 tests per hour.
In early 2021, the Basel-based company said it could perform around 50 million new tests per month, in addition to the rapid point-of-service tests it already sells.
Roche said the test could be deployed in places such as nursing homes or hospitals, where rapid results could thwart a potentially fatal outbreak.
“The primary use case is testing symptomatic patients,” a Roche spokesperson said. “The secondary use case is testing individuals with suspected infection… which could also include asymptomatic patients. ”
Expert opinion on how to use antigen testing is evolving and is still the subject of debate.
PCR remains the benchmark for diagnostic tests
Switzerland, where new reported infections reached 2,823 cases on Wednesday from three a day in June, is only now validating the accuracy of rapid tests.
“The deployment of rapid tests – where it makes sense – will be built into our testing strategy,” a spokesperson for the Swiss Ministry of Health said. “We will update our testing recommendations in November. ”
Sandra Ciesek, director of the Institute of Medical Virology at the University Clinic in Frankfurt, Germany, said rapid antigen testing could be an option for asymptomatic people planning to visit elderly patients in nursing homes.
But people should refrain from using them as a definitive surrogate for judging their infectious status.
“The PCR test remains the gold standard,” Ciesek said. “An antigen test should only be used as an alternative if PCR is not possible in a timely manner. “