Policy Shift on COVID Testing Leaves Israel in the Dark

Home COVID testing prioritizes at-risk groups and prevention of hospitalization. In the current omicron wave, unlike before, Israel has to choose what to focus on

Ido Efrati
Ido Efrati
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Long lines at Israeli COVID testing sites, this week
Long lines at Israeli COVID testing sites, this weekCredit: AMIR COHEN/REUTERS
Ido Efrati
Ido Efrati

Given the rapid rise in COVID infections, the transition to the widespread use of rapid antigen testing as Israel’s official diagnostic tool, thereby opening the bottlenecks that had formed in the PCR testing system, was inevitable.

PCR tests will now be administered only to at-risk groups. That makes sense: PCR tests are more reliable and precise in diagnosing variants, which is important for higher-risk populations.

Other Israelis will from now on be asked to check themselves with a home test (at their own expense) or to undergo a rapid test at one of the official antigen-testing sites. But, the antigen test is less sensitive and reliable than the PCR, especially in identifying asymptomatic infections, and there is a price to pay in missing the risk of missing infected individuals.

Home testing has the advantage of producing fast results, thereby saving precious time in making diagnoses and preventing COVID carriers from inadvertently infecting others. But reliability is a problem vis-à-vis home testing, which is by nature done by people without the necessary skills or understanding to always complete it properly.

Beyond that, the new testing policy will be leading to a major change in the epidemiological picture available to decision makers. Like many other countries, Israel has relied on the PCR test as its main barometer for measuring the extent and change in the number of coronavirus infections. The number of confirmed COVID cases is the immediate and tangible number for the spread or the containment of the virus.

The PCR test is not precise: There are many cases that are not successfully detected or are only detected after the fact by serological testing, including apparently many children. Nevertheless, it has served as an epidemiological measure along wide more concrete data, such as the number of hospitalized and seriously ill patients.

The change in the testing policy to limit PCR testing to only part of the population and to put the burden of rapid testing and reporting on individuals will widen the gap between the information decision makers have in hand and a true picture of the growing omicron pandemic. The data they will have to work with will be less precise than before, restricted to figures on symptomatic and hospitalized patients, which provide only a lagging indicator for the spread of the virus.

Experts say there are other epidemiological tools they can use to surveil the spread of the virus, such as sampling of sewage. Another is focus group surveys, which can be used to build statistical analyses the way testing is conducted for the flu. However, they cannot provide a picture of COVID trends in real time.

Prof. Hagai Levine, chairman of the Israeli Association of Public Health Physicians, said this problem is known in epidemiology as the "iceberg" phenomenon. “But if we know how to filter it and look at it properly, we can get a good epidemiological intelligence picture – for example, by strictly carrying out methodical testing of hospital patients,” he said.

The number of confirmed cases was never a good criterion of the severity of the situation. Even so, Levine conceded, it won’t be easy to find an alternative to the information provided by numerous tests.

That said, at this juncture it is difficult to fully assess the true loss to epidemiologists and decision makers by the absence of daily data, Levine said. The fact is its value may already become objectively diminished: With the Israeli population consisting of so many groups of differing levels of risk and protection – vaccinated recovered, recently vaccinated, vaccinated earlier, in the process of vaccination, unvaccinated, children, adults – there are a plethora of statistical axes to track.

In the omicron wave, unlike previous ones, epidemiologists and decision makers will have to choose where to focus. And at this point, with the pandemic raging, the health care system wants to know first of all who has been infected and what their chances are of their having to be hospitalized. They will need to know less about how many have been infected, even at the price of giving up the broader picture.

With Israel's testing capacity facing severe bottlenecks, PCR tests are a prized resource saved for the country's most vulnerable.Credit: Rami Shllush

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