Israel was down to a handful of daily COVID cases. Now it's around 11,000. What happened?

Just months ago, Israel wasa world leader invaccinating its population andappeared to be puttinga stranglehold on thevirus that causes COVID-19, wrestling down its daily case count to double digitsand at times,near zero.

But any potential celebration was short-lived, as the more contagious delta variant gained traction and spread quickly, to the point where Israel's most recentdaily case countwas around 11,000 a levelnot seen since January.

According to some Israeli scientists, this reversal of fortune provides lessons forcountries like Canada, as we entera fourth wave, to remain cautious about lettingany guarddowntoavoid some of the mistakestheir country made.

"This is a very clear warning sign for the rest of the world," said Dr. Ran Balicer, chief innovation officer at Clalit Health Services (CHS),in a recent interview with the magazine Science.

"If it can happen here, it can probably happen everywhere."

While Israel often topped the list by Oxford University-based Our World in Data ofpopulation vaccinated,now it's leading in another category:It has theworld's highest seven-day rolling average of new daily coronavirus cases per million people.

Daily record

On Tuesday, Israel's Ministry of Health reportedthat the country had set a new daily record for diagnosed coronavirus cases at nearly 11,000, which comes as the delta variant surges across much of the world.

There were 716 people in the country hospitalized and in serious condition with COVID-19 complications, including 159 on ventilators,the Times of Israel reported.

And while Israel went several weeks in May without a death, more than 550 people have died of COVID-19 in August, including over 100 of them in the last five days, the Times reported.

"It seems that some mistakes were made when we thought we won the war, and now we understand we only won the battle.The war is still here, and we have to continue and to explain and push all the people to get vaccinated," Israel's coronavirus czar, Prof. Salman Zarka,said in a recent interview with the Times.

Meanwhile, Israeli health officials reported what appeared to be a waning efficacyof the vaccine, including amongthose who had beendouble vaccinated. Data showedthat of the serious cases being admitted to hospital, around 60 per cent of patients were people who had been fully vaccinated, though most were over 60 or with underlying health conditions.

Herd immunity believed reached

"Many public health professionals feel that what happened in Israel was a demonstration of population immunity, or herd immunity.[But the] delta variant, with its higher infectious rate, coupled withwaning immunity, has proven us wrong," said Dr.EyalLeshem, a clinical associate professor in internal medicine and infectious diseases at the Sackler School of Medicine in Tel Aviv University, in an interview with CBC News.

In May, withherd immunity believed to have beenestablished and cases dwindling down to double digits, with few deaths, Israel began easing up on its public health restrictions. Businesses and schools were returningto normal.

Then,at the beginning of June, capacity limits at stores and restaurants were lifted, as well as for indoor and outdoor gatherings. Israelis also no longer needed proof of vaccination toenter various venues.

By mid-June, indoor mask requirements were lifted.

"The government decided we shouldn't impose restrictions;we will rely on vaccines for protection. Butthen we realized that it is very difficult to stop the infections with the delta variant," saidCyrille Cohen, head of the lab of immunotherapy atBar-Ilan University and a member of the Israeli Health Ministry's advisory committee for clinical trials on COVID-19 vaccines.

"What we should have doneis to keep some restrictionsfor example, wearing of the mask inside," he said.

As the country's cases rapidly increased again, the government reversed course.Mandatory masks and its green passregime wereagain required to enter indoor public spaces.

BetweenJanuary and March, Israel had been very proactive and innovative, explainedNadav Davidovitch, director of theSchool of Public Health at Ben Gurion University of the Negev. "And then we became much more passive."

Significant number still unvaccinated

Israel has so far fully vaccinated around 62 per cent of its population.But that still leaves a significantnumber of people unvaccinated, said Dr. Isaac Bogoch, an infectious diseases physician and member of Ontario's COVID-19 vaccine task force.

"You've got a million unvaccinated folks,plus a very contagious delta variant, plus opportunities for the virus to be transmitted," he said."So you can't get surprised that there's a big rise in cases."

The most cautionary tale for Canada could be observations that the rate ofinfection has been found to be higher in peoplevaccinated back in January, compared with peoplewho were vaccinated in April, said Leshem.

"Insimple words: That protection against infection is waning over time."

These results were observed in people who were double vaccinated, regardless of age or whether they were immunocompromised, he said.

Leshem said this development, along with the fear that a rise in severe infections would overwhelm the health-care system,prompted Israelto become the first country to launch abooster shot campaign, with a third dose going to those aged 60 and over. Boostersare now available to everyone aged 30 or older.

So far, the resultsof the boostercampaign suggest the third dose is probablyeffective both in preventing infection and in reducing the number of severe breakthrough infections and hospitalization, Leshem said.

"So what we're seeing on the ground in COVID wardsin my hospital and other hospitals is that while the number of cases continue to increase, we've seen a stabilization in the number of severecases," he said."Themost plausible reason is that this older population that was boosted is more protected against severe infection, hospitalization and death."

The disease is still expanding,Leshem said, and Israel is still seeing more and more cases every day"but at a slower rate."

According to Cohen, the lesson countries like Canada can learn from Israel's experience is that afocusmust be maintained on the populations at highest risk.

"As the number of infections rises, you really want to make sure this population is protected in an optimal way," he said.

Limit gatherings

In terms of policy, governments need to maintain some level of restriction, like limiting gatherings, said Cohen.

"I was a proponent of having tighterrestrictionslike a month-and-a-half ago. That was actually my personal advice when I was asked byofficials here so that we would not end up in this situation," Cohen said. "They decided against that."

To Canadians and Canadian lawmakers, his advice is to open up graduallyand the momentthere isa steady rise in cases, don't waitto act. "Because the higher the rise, the more difficult it is to stop with simple measures."

He also advises that peoplekeep maskingwhile indoorsand to use rapid testing for vulnerable people attendingfamily gatherings.

And his message to Canadians who were vaccinated more than six months ago:"You are vulnerable.You are more vulnerable than what you were three months ago, especially when facing the delta variant."