Israel's Fluctuating COVID Infection Rate Makes Pandemic Predictions Difficult

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The Carmel Market in Tel Aviv, yesterday.
The Carmel Market in Tel Aviv, yesterday.Credit: Hadas Parush

Coronavirus infection and illness data for Israel has been very volatile over the past week, making it difficult for experts to determine whether the pandemic is receding or spreading.

The infection coefficient – the famous R number, which represents the average number of people that each infected person will infect in turn – had dropped gradually to reach 0.81 last Monday, suggesting that the latest wave of infection was weakening. But it has risen over the past week, reaching 1.01 Monday.

While the R number could be a preliminary sign of the outbreak continuing, it is calculated based on data from the previous 10 days, and is thus easily influenced by the sharp changes in the infection data during the past week; the number of new infections jumped or dropped by the thousands on consecutive days, while the percentage of tests coming back positive every day also varied widely. Experts, therefore, warn that the R number must be taken with a grain of salt until the trend is clearer.

Other variables may also influence understanding of the morbidity situation: The opening of the school year, the huge antigen testing campaign conducted among 1 million schoolchildren, and the sharp changes in the number of tests conducted each day (especially on holidays). The holiday period, characterized by masses of family gatherings, prayers and celebrations, is another factor making analysis difficult.

The number of the seriously ill in hospitals dropped during the first week of September, began to rise again and on Monday dropped a bit to 691 people. Another hundred patients in serious but stable condition are in geriatric facilities or being cared for at home. Although the latest number is higher than last week, the number of seriously ill generally expresses the spread of the virus 10 days to two weeks prior. Experts were expecting a rise in infections in September, once the school year started, after there had been signs in late August that the outbreak was waning after hundreds of thousands of people got the booster shot.

“When we look at the statistics at the weekly level, we see that last week, between September 6 to 12, there were 532 new severely ill patients and 56,000 new confirmed cases,” said Prof. Eran Segal of the Weizmann Institute of Science, in Rehovot. “On the other hand, the previous week, there were some 65,000 new cases and 619 severely ill patients. We see that last week there were 3 percent more tests than the previous week, and yet nonetheless there was a 15 percent drop in the number of confirmed cases and a 16 percent drop in the number of seriously ill. The Health Ministry calculation may indeed be showing an infection coefficient of 1.01, but these changes stem from the holidays, which influenced the fluctuations.”

Another trend that’s clear is the ratio of unvaccinated people among the severely ill. Of the 691 severely ill patients in hospitals, 446 were completely unvaccinated and 166 had received two doses. Only 58 had received the booster shot. The ratios are similar when analyzing new infections.

A report from the Center for Information and Knowledge in the Battle Against the Coronavirus released Monday defined the trend as “A rise in serious illness among young, unvaccinated people, alongside a drop in the general morbidity.”

The report adds, “The rise continues in the number of confirmed cases and the seriously ill who aren’t vaccinated – particularly among the unvaccinated under 60. As of today, most of the patients in serious condition are unvaccinated, even though they are a clear minority of the population eligible for vaccines in Israel.”

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