Explained: Is Israel Facing Another COVID-19 Wave as the Delta Variant Spreads?

The delta COVID variant has been identified in more than 80 countries, and Israel fears that infections will spike without renewed restrictions. What makes it so contagious and how effective is the vaccine against it?

Ido Efrati
Ido Efrati
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Vaccinating teens at Rishon Letzion, this week.
Vaccinating teens at Rishon Letzion, this week.Credit: Ilan Assayag
Ido Efrati
Ido Efrati

UPDATE: Israel sees outbreak of more contagious delta variant. The panic is needless

The uptick in the number of new coronavirus cases in Israel in recent days has aroused fears that the country is heading back to social-distancing rules and lockdowns. Yet, in spite of the outbreak in a few parts of the country, such measures don’t seem to be in the offing.

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It appears that the rise in new cases is due to the delta variant of the coronavirus. The variant, which is also known as B.1.617, was first identified last October in the Indian state of Maharashtra and from there spread to the rest of India and then on to other countries.

According to the World Health Organization, the delta variant is now the dominant form of the coronavirus globally and is found in more than 80 countries. In Britain, for example, the rate of contagion has risen from 24 cases per million people to 126 in the last month due to the arrival of the delta variant.

The rate of complete inoculation (two doses of the vaccine) in Britain stands today at 45 percent, compared to Israel’s 65 percent, including those who became immune by contracting the virus. Under the circumstances, Israeli officials are worried that without restrictions being reimposed, the arrival of the variant to Israel might spell a similar jump in new cases among unvaccinated people and even among those who are.

A girl receiving her coronavirus vaccine in Kfar Saba, earlier todayCredit: Avishag Shaar-Yashuv

How did the delta variant become dominant?

The most prominent characteristic of the delta variant is its fast spread: Estimates are that the variant is 1.5 times more contagious than the alpha variant, which was first seen in Britain. To illustrate the difference, the R number – the average number of people each coronavirus carrier infects – for the coronavirus cases first identified in China’s Wuhan was three. The alpha variant has an R number of about five, whereas the delta variant's number stands between six and eight.

What makes the delta variant so highly contagious?

Based on what we know so far, the delta variant is no different in its basic structure than other variants of the coronavirus. Like the others, it can be identified by certain genetic changes in its spike protein that covers the virus. The spike protein gives the virus its signature crown-like appearance and enables it to attach to target cells.

The delta variant involves two mutations to the spike protein. One, called L452R, is also found in the California variant of the virus. The second, which is called E484Q, is found in the same place on the spike protein (location 484) as other genetic mutations of the virus, for example the South African and Brazilian variants. Scientists say these mutations enable the virus to attach more easily to the host’s cells, in particular lung cells. The better a virus’ ability to attach, the fewer viruses are required to transmit the disease and infect the host.

In the second half of last year, quite a few variants were identified, but fewer than eight of them have reached Israel. Some of these prompted concerns that they would become more contagious, more virulent and resistant to vaccines. In practice, only the alpha variant has become a significant factor in Israel and other places; the others remain marginal.

Scientists believe that the genetic changes in its spike protein make the delta variant more contagious than other variants, as well as more resistant to the vaccine. Scientists say the variant might have other features that are not yet known.

How effective are vaccines against the delta variant?

Research findings, including those by British health authorities published in the medical journal Lancet, show that two weeks after the second dose is administered, the Pfizer-BioNTech coronavirus vaccine is 88 percent effective against the delta variant. That is only slightly less than the 93 percent for the alpha variant.

As far as preventing the need for hospitalization for COVID carriers, data published last week by British health authorities, based on an analysis of about 14,000 cases, shows 96 percent efficacy following two doses of the Pfizer vaccine.

How do vaccinated people get infected?

The vaccine does not provide 100 percent protection, including against the original version of COVID-19 that can be traced back to Wuhan. In regard to the delta variant, inoculations have so far been shown to be slightly less effective than against the Wuhan and alpha variants, but it is still high.

The effectiveness of a vaccine involves additional factors apart from the contagiousness of the virus itself, such as the extent of people’s exposure to the virus and the quantity of the virus that enters their body, as well as how well their immune system functions and the antibodies it produces. Exposure to large amounts of the virus, especially those with the features of the delta variant, can penetrate vaccine defenses.

How common is infection among people who are vaccinated?

Based on what we have seen over the past few months, vaccinations have led to a dramatic drop in new coronavirus cases, serious cases and deaths. Nevertheless, the data also shows that vaccination does not eliminate the prospect of infection. According to Israeli Health Ministry figures that were provided to Haaretz last month, 564 new cases were reported between May 22 and June 20. Of those, 385 were of people who had not been vaccinated against COVID, 13 of people had taken just the first dose and 165 of people who had two doses. In other words, 29 percent of those who contracted COVID had been inoculated.

What does the delta variant mean for herd immunity?

The higher Israel’s vaccination rate is, the fewer opportunities there are for the virus to spread and replicate itself. A certain rate of vaccination creates herd immunity, meaning contagion is suppressed enough that the entire population is protected, including those who have not been vaccinated. If a variant is better able to find and exploit paths of contagion, more of the population needs to be vaccinated in order to reach that threshold.

Why are experts recommending that 12-to-15-year-olds be vaccinated?

At the beginning of June, when Israel’s coronavirus rates were still very low, health authorities approved inoculating the 12-to-15-year-old age group with the Pfizer vaccine. However, reports have emerged of an uptick in cases of myocarditis (inflammation of the heart muscle) among people aged 16 to 30 who have been vaccinated. The great majority of the cases were minor and passed quickly.

Weighing that risk against the coronavirus risk, experts decided in favor of approving vaccination for 12-to-15-year-olds. Today, with a rise in coronavirus infections and with the millions of vaccinated children around the world already inoculated, Israeli experts have decided to recommend – not just approve – that children be vaccinated against the virus.

Is Israel on its way to another coronavirus wave?

There are many reasons to assume not. The development of vaccines has marked a turning point in the war against the virus globally; vaccination campaigns are moving the world closer to the point where the pandemic is contained. Even if theoretically, a new more virulent and contagious form of the coronavirus emerges that exhibits greater resistance to the vaccine, the road to developing a tailored vaccine for it will be shorter and faster than the first time around.

Beyond that, recent COVID outbreaks in Israel have so far been geographically confined, even though Israel has lifted all restrictions, people are no longer wearing masks and 40 percent of the population has yet to be vaccinated. For now, the Health Ministry is not rushing to reimpose coronavirus restrictions that would impinge on the public’s day-to-day life. Instead, it is relying on contact tracing, expanded testing and stepped-up monitoring of people leaving and entering the country through Ben-Gurion International Airport.

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