Covid-19: Pfizer vaccine efficacy declines by one third in Israel, says health ministry

Government data suggests Pfizer-BioNTech vaccine continues to provide strong shield against severe Covid-19

A teenage girl receives a dose of the Pfizer-BioNTech Covid-19 vaccine

 in Holon, near Tel Aviv, on 21 June (AFP/File photo)

By MEE and agencies
Published date: 5 July 2021 

The efficacy of one of the world's leading Covid-19 vaccines has declined by nearly a third in Israel due to the spread of the delta variant, the country's health ministry has said.

Ran Balicer, chairman of Israel's national expert panel on the coronavirus, said the Pfizer-BioNTech vaccine had a 64 percent protection rate from early June until early July - a significant decrease from the 94 percent efficacy researchers had documented a month earlier.

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The findings come as Israel reverses some Covid-19 restrictions that had been lifted out of concern for the uptick in delta variant cases.

The health ministry said on Monday that the Pfizer vaccine continued to provide strong protection against severe symptoms of the virus, with people avoiding hospitalisations by a rate of 93 percent from 6 June to 3 July, compared to a 98 percent rate in the previous period.

Nevertheless, Balicer warned that the rise in cases offers a "preliminary signal" that the vaccine may be less effective at preventing mild symptoms from the delta variant.
Delta, Israel's 'dominant strain'

While it remains "too early to precisely assess vaccine effectiveness against the variant", Balicer told AFP that "some decrease in vaccine effectiveness against mild illness - but not severe illness - is likely".

Later on Twitter, Balicer underlined the difficulty in compiling data about the delta variant from local outbreaks, describing the work as "very population-segment-specific, complex, & sensitive to significant bias".

The Covid-19 delta variant was first identified in India in October and has since spread to nearly 100 countries worldwide. It is more than twice as contagious as the original Covid-19 virus and has forced a number of governments, including the UK, to delay or rethink lifting pandemic restrictions.

The delta variant's emergence as the "dominant strain" in Israel has led to a "massive shift in the transmission dynamic", said Balicer.

On Monday, Israel reported the highest rate of new infections in three months, with the ministry recording 343 new cases over the past 24 hours. After a peak of over 10,000 new cases in one day in January, new daily cases had fallen to the single digits in June.

In the past fortnight 90 percent of new cases in Israel have been caused by the delta variant, AFP reported. About half of new cases have been detected in fully vaccinated patients, and about half in children, with a handful of returning travellers testing positive.

'It is encouraging'

Experts "remain hopeful that the vaccine effectiveness against serious illness will remain as high as it was for the Alpha strain", Balicer said.

The number of fully vaccinated Israelis experiencing severe symptoms after contracting the virus had increased from roughly one every other day up to five per day, Balicer estimated while also noting a lack of fatalities.

"It is encouraging that we still maintain zero deaths for the last twelve days," he said.

After recently reimposing an indoor mask rule for public spaces, Prime Minister Naftali Bennett was scheduled to meet Health Minister Nitzan Horowitz on Monday to discuss the latest outbreak and whether to advise a third booster shot for certain demographics.

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Israel may also consider limiting the size of permitted gatherings and reintroducing the “Green Pass” system that limited access to certain spaces to vaccinated people, Bennett said on Sunday.

Pfizer CEO Albert Bourla has said people will "likely" need a third dose of a Covid-19 vaccine within 12 months of getting fully vaccinated.

A Pfizer spokesperson declined to comment on the data from Israel but told Bloomberg that other research suggested the vaccine provided ongoing protection against new mutations. Available evidence suggests the vaccine "will continue to protect against these variants", she said.

Israel originally lifted mask requirements on 15 June, reinstating them two weeks later.

Some 5.2 million people have received both doses of the Pfizer-BioNTech vaccine in Israel.

But Israel, which has vaccinated some 85 percent of its adult population, has faced criticism for not sharing its vaccines with the 4.5 million Palestinians in the occupied West Bank and the Gaza Strip. Under international law, occupying powers are responsible for the health care of the population they control.


Israel Sees Pfizer Vaccine Efficacy Decrease Against Delta Variant, Still Very Effective Against Severe COVID-19

By Dr Alfredo Carpineti05 JUL 2021

Israeli news site Ynet has reported that based on the number of cases of COVID-19 breakthrough infection reported by the Israeli Health Ministry, the efficacy of the Pfizer/BioNTech vaccine against mild cases caused by the Delta variant appears to have decreased. Fortunately, the vaccine appears to still be highly effective against the most serious cases.

The reported numbers suggested that between May 2 and June 5, the efficacy against the disease was around 94 percent. Since June 6, the efficacy appears to have decreased to 64 percent. When it comes to hospitalizations, the efficacy seems to drop only marginally from 98.2 percent to 93 percent.

While the drop in efficacy is concerning, it is important to state that there could be several factors at play here, and we should wait for more data to begin to build a complete picture. One possibility, also seen in other countries, it’s that the infections happened before a strong immune response might have developed. Fully vaccinated people are counted from the moment they get the second jab of the two-dose vaccines, but strong immunity doesn’t really kick in until at least two weeks later.

The Israeli government is considering reintroducing social distancing measures. These were lifted mid-June, but things like masks in closed spaces came back on June 25. They are also considering a booster vaccination campaign, although the percentage of vaccinated people, while high, remains below the threshold for herd immunity.

Breakthrough infections are to be expected simply because vaccines are not 100 percent effective. The danger lies in infections being allowed to propagate through a population uncurbed. A new variant of the disease could emerge, against which the vaccines are ineffective. Fortunately, this has not happened yet.

[h/t: Ynet/Bloomberg]