Israel says the Delta variant is infecting vaccinated people, representing as many as 50% of new cases. But they’re less severe.

A healthcare worker injects a vaccine in a person's arm.
An Israeli receives a coronavirus vaccine in Tel Aviv on January 6. Sebastian Scheiner/AP
  • As many as half of new COVID-19 cases in Israel are vaccinated people, a health official suggested.
  • The Delta variant, not as easily beaten by vaccines as other variants, is driving Israel’s surge.
  • The figure is likely an estimate, as the health ministry is still analyzing the cases.
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As Israel faces a surge in cases driven by the Delta variant, its health officials suggested that as many as half of new cases were among people who’d been vaccinated.

Fully vaccinated people who’ve come into contact with the Delta variant will have to quarantine, Chezy Levy, the director-general of Israel’s health ministry, said on Wednesday, Haaretz reported.

“Even though the numbers are low, the fact that this is reaching vaccinated people means … that we are still checking how many vaccinated people have also been infected,” Levy said, according to Haaretz.

Levy told the state broadcaster Kan Bet that about 40% to 50% of new cases appeared to be people who had been vaccinated, Haaretz reported. He did not appear to specify a time frame for the new cases.

The figure is likely an estimate, as the ministry is still analyzing the cases. On Monday, Levy said that a third of the new daily cases were people who had been vaccinated.

It also wasn’t clear whether those people had been fully or partially vaccinated.

Though they are preliminary, the figures underline the worry that the Delta variant could mean the virus continues to spread even in places like Israel where large portions of the population have been vaccinated.

New daily cases reported in Israel have jumped to over 100, the highest level there since May. About 70% of the cases have been caused by the Delta variant, Levy said on Monday.

Israel had been ending its virus restrictions – it ended indoor masking last week as daily cases hovered in the single digits.

A graph shows waves of new daily COVID-19 cases in Israel since March 1, 2020. It shows a very slight uptick in cases recently.
Daily new confirmed COVID-19 cases in Israel, as of Wednesday. Our World in Data

As of Thursday, about 57% of Israel’s population had been fully vaccinated, according to Johns Hopkins University data.

Though the infections among vaccinated people have alarmed Israelis, the infections do not appear to be as severe as they are in unvaccinated people.

As of Monday, no severe cases of COVID-19 had been reported from the latest surge, Ran Balicer, an executive at the Israeli healthcare organization Clalit, said in a tweet.

Of all the coronavirus variants, the Delta variant could pose the greatest risk to vaccinated people. Research suggests it’s better able to break through in people who’ve had only one dose of two-dose vaccines, such as those from Pfizer and AstraZeneca.

On Monday, Mike Ryan, the executive director of the World Health Organization’s health-emergencies program, said the Delta variant could “be more lethal because it’s more efficient in the way it transmits between humans.”

Two doses of the vaccines appear to be protective against Delta.

An analysis by UK health officials found that two doses of Pfizer’s vaccine were 88% effective against Delta while a single shot was 33% effective. That’s compared with 95% efficacy against the original strain, or 52% after one shot.

But no vaccine is 100% effective, and so-called breakthrough cases are still possible.

With other variants, breakthrough infections were mostly mild.

In the UK, where the Delta variant makes up more than 90% of cases, 26 of 73 total deaths associated with the Delta variant were among people who had been fully vaccinated, The Telegraph reported this week.