Which COVID-19 test is the best?

• Published date: 28 September 2021
• Author: Walla!

For way too long, corona testing has been part of our weekly routine, but lately, with places limiting entrance to holders of the Green Pass, it's the main topic of our daily conversation.

Walla!, a sister publication of The Jerusalem Post, invited Prof. Amos Adler to its "Experts' Clinic" podcast. He heads the microbiology laboratory at Tel Aviv Sourasky Medical Center, and we asked him to explain the difference between the current corona tests, how reliable their results are, and who should take serological tests. Here are his answers.

Which test is more effective, the rapid antigen test or the PCR?

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The speed tests, called antigen tests, have a reputation for being of lesser quality. But, according to Adler, they hold a significant advantage over the more accurate PCR test.

"The PCR test is super sensitive," explained Adler "and will know if you have RNA in the airways when you're sick and contagious, and even when you have long since stopped being contagious. That is, it can be positive weeks and in some cases even months after you were infected."

According to him, in this case the sensitivity of the test is problematic, as it means that in some situations people are labeled as positive even when it's irrelevant. This is why coronavirus testing is not currently performed at the end of isolation if someone isn't symptomatic.

The antigen test, on the other hand, is ostensibly a less sensitive test, but it has an advantage: it can detect the vast majority of people who have an infectious viral load.

"Its insensitivity is actually an advantage in this regard," explains Adler.

Therefore, in communal settings where the risk of corona is relatively low, the antigen...