Israel Still Not Sure Omicron Causes Milder Illness, Despite Research

Which variant do seriously ill Israeli COVID patients have, and how many have underlying conditions? Lack of clear information is making it difficult for doctors to precisely assess the nature of severe illness caused by omicron

Ido Efrati
Ido Efrati
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The emergency room at Wolfson Medical Center, Holon, on Monday.
The emergency room at Wolfson Medical Center, Holon, on Monday.Credit: Hadas Parush
Ido Efrati
Ido Efrati

As the number of new COVID infections in Israel continues to break records on a daily basis, the health system is anxiously charting the number of seriously ill hospitalized patients. Yet a month and a half after the omicron variant hit Israel, and after several international studies suggested it causes less severe illness than earlier variants, Israeli experts are still unable to confirm whether that is the case.

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According to some studies – including in South Africa, where the latest variant was first identified – the risk of becoming seriously ill with omicron is one fifth of that of people with the delta variant. However, the number of seriously ill COVID patients is connected to the number of daily infections, which passed the 30,000 milestone on Tuesday. Thus, a low risk could still lead to a large number of seriously ill patients as the numbers spike.

Aside from these numbers, people in the health system are examining the nature of the serious illnesses, comparing it to those caused by earlier waves.

Any change in the characteristics of serious illness could have a huge impact on health services. These changes could be expressed in the length of hospitalization, the need for ventilation or being hooked up to an ECMO machine, with implications for infrastructure, available hospital beds and methods of treatment. A key issue concerns manpower as medical personnel either become infected and need to go into quarantine, or must isolate after having close contact with someone who tested positive.

The number of hospitalized patients in serious condition has risen sharply in recent days. There are currently 247 seriously ill people in hospital – almost double the number last week when there were 132. Two weeks ago, the number was 85.

The number of seriously ill people being admitted to hospitals is also higher. On Tuesday there were 56 new admissions, with 52 the day before that and 70 over the weekend. Most of them are now improving. Of those 247 seriously ill patients, 108 were vaccinated; 186 of them are aged 60 or over, 26 of them are over 90 and 57 are between the ages of 80 and 89.

It’s difficult at this stage to know whether there are typical features caused by omicron among the seriously ill. Many of these patients are older, with diverse underlying conditions. The number of seriously ill patients includes those who were admitted to other departments for reasons not associated with coronavirus, but were subsequently transferred to COVID wards after testing positive.

Thus, the rise in seriously ill patients also expresses the spread of omicron in the general population, not necessarily the incidence of serious illness caused by the virus.

Another problem when it comes to understanding the severity of omicron is the absence of clear information about the variant with which patients have been infected, since not all hospitals have kits that can diagnose the specific variant. Ninety-five percent of infected people in the general population have the omicron variant (where the variant has been identified), so the assumption is that most of the people in hospitals are also omicron carriers.

Too soon to say

These issues combined are making it difficult for doctors to precisely assess the nature of severe illness caused by omicron – which is why some say it’s too early to do so.

This is the position taken by Prof. Galia Rahav, head of the Infectious Diseases Unit at the Sheba Medical Center in the Tel Aviv suburb of Tel Hashomer. She says serious illness cases at her hospital started only last Friday. “Until then, we only had two to three patients a day, not seriously ill ones. Since then, we’ve been receiving 30 patients at a time.”

She adds that until last Friday, a third of new patients were coming from other departments after testing positive for COVID, but that those patients now comprise less than a quarter of new admissions.

“We had four patients going to the intensive care unit, one with myocarditis [inflammation of the heart muscle] – I’m not sure we can still say the illness is less severe,” she cautions. “When you look at Denmark, for example, the number of hospitalized patients is the same as it was with the delta variant, even though there are less deaths.”

A patient and medical staff at Shaare Zedek Medical Center in Jerusalem's coronavirus ward, on Monday.Credit: Emil Salman

Evidence globally, as well as reports on preliminary lab studies on animals, suggest that the effects of omicron are different. According to these studies, omicron tends to affect the upper respiratory tract more than lung tissue, in contrast to the earlier variants that induced severe pneumonia.

Prof. Dror Mevorach, head of the COVID ward at Hadassah University Hospital, Ein Karem, says his department has been treating 150 patients, 80 of whom were hospitalized, even though not all of them were seriously ill.

“The clinical picture emerging so far is that there are more symptoms in the throat, with more sore throats than we saw with the delta and alpha variants,” he says. “There are more symptoms in the upper respiratory tract and fewer in the lower tract. There are also more headaches and much fewer reports of a loss of taste and smell.”

Mevorach explains why the virus centering on the upper respiratory tract rather than the lower one is of great significance: “The symptoms are unpleasant, but it’s much better than having the lungs involved – a situation that causes shortness of breath,” he says.

According to the Hadassah professor, even when patients do experience lung problems, “it’s less intense compared to what we saw with the delta variant. From what we’ve seen so far, much fewer patients with moderate or serious illness need vigorous oxygen supply, with fewer transfers to intensive care units compared to delta and alpha. This doesn’t mean you can’t have a seriously ill patient with the omicron variant. But it’s much rarer, usually occurring in unvaccinated people or in older people with an underlying medical condition.”

Mevorach adds that in contrast to the earlier waves, it appears that the disease is also less severe among older people this time around.

However, it’s still hard to say with certainty that the disease doesn’t reach the lower respiratory tract.

Dr. Amos Dodi, an expert in pulmonary disease and intensive care working in New York, tweeted in Hebrew a few days ago: “It’s important to clarify: We don’t see the omicron variant causing severe lung failure like delta did. But in contrast to early reports indicating that omicron only affects the upper respiratory tract, we see that as with other respiratory viruses, it can lead to lung failure. Unvaccinated and immunosuppressed people are at high risk.”

Other doctors say that many of their patients were first admitted for other reasons and were only later found to have COVID. Dr. Khetam Hussein, the head of the Infection Control Service at Rambam Health Care Campus, Haifa, says these patients had very few COVID symptoms. However, she notes that people arriving at her hospital because of coronavirus have the same disease as earlier variants, even though it’s a bit less severe among vaccinated people.

The director of an intensive care unit at one Israeli hospital notes that most of the patients he sees are quite old and with underlying conditions, with omicron a secondary factor in the deterioration in their condition. He says that “the index of seriously ill patients is a misleading one, since it doesn’t distinguish between patients and does not indicate the reason for the deterioration in their condition.”

Prof. Oren Zimchoni, director of the infectious diseases unit at Kaplan Hospital, Rehovot, says the definitions being applied to coronavirus patients are not distinguishing between serious illness deriving directly from the virus itself and the deterioration of a chronic existing medical condition. “Often, a serious condition is the result of the exacerbation of an underlying disease, not of pneumonia caused by the coronavirus,” he says.

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