The most effective means to fight the coronavirus is to keep carriers separate from healthy people. The way to do that is to identify carriers. But Israel continues to be plagued by long waits between tests and results.
However, a testing tool developed during the first coronavirus wave by Israeli researchers is undergoing final validation and should be available for use by winter – when the public could suffer from a combination of flu and COVID-19.
Researchers at Technion-Israel Institute of Technology and Rambam Health Care Campus say that the “pooling” method they successfully tested in March, which would increase testing capacity and speed, is undergoing final validation; they hope it will be accessible to hospitals and health fund labs soon.
Pooling, which has been used since World War II and became better known in the 1990s as a way of testing for HIV, enables simultaneous testing of dozens of samples.
“Implementing pooling in the final stage of the PCR molecular test will make it easier for us to shorten the entire process and significantly increase the test rate,” said Dr. Moran Szwarcwort-Cohen, director of the Rambam Virology Lab. “We are doing all the validation now to be ready for winter.”
The team’s pooling approach allows molecular testing to be performed on a “combined sample,” taken from 32 or 64 patients.
“This way we can significantly accelerate the testing rate,” Technion research Idan Yelin explained. “Only in those rare cases, where the joint sample is found to be positive, will we conduct an individual test for each of the specific samples.”
This method reduces workload, Yelin said, at a time when Israel’s lab workers have stressed that they cannot manage the daily testing load. Currently, Israel is screening an average of 25,000 people per day.
The method also saves supplies. Israel could face a shortage of the chemical reagents needed to perform PCR tests in the next few months, as daily screening is expected to be boosted to at least double if not more than the current rate.
Yelin explained that there are two different types of pooling. The first, more basic method takes a number of samples collected from nasal and throat swabs, mixes them together and tests them once. Groups of samples that test negative are ruled out. If a group tests positive, every sample in that group is then retested individually.
The Technion-Rambam group recommends using an automated system to apply a one-step method that allows labs to process all the tests in one round with many overlapping groups. This increases the number of tests but also saves time.
But with the percentage of people who test positive being around 5% to 6%, pooling is less valuable, Szwarcwort-Cohen pointed out. The process works best when around 1% are positive.
But Yelin said that, assuming this newest round of restrictions is effective and Israel is once again able to flatten the curve, then the testing could still be rolled out to enable fast screening at senior living centers, for example, where regular testing is already occurring. This would allow the Health Ministry’s Magen Avot v'Imahot (Parents Guard) to identify people who have coronavirus even more quickly.
He also said that it would help the ministry move toward testing more asymptomatic patients.
“There is no reason not to do this – the sooner the better,” Yelin added. “In winter, a lot of people will have respiratory diseases and will really want to know if they have SARS or something else. There are going to be a lot of people being tested – even more than now – and we will need this. All we need is the green light from the Health Ministry."