JERUSALEM – Israel once again has placed itself in the middle of the global clinical debate on the medical benefits of a fourth Pfizer shot to slow the Omicron wave, when it became the first country to approve such an injection for all citizens over the age of 60 and healthcare workers.

Israeli Prime Minister Naftali Bennett announced the roll-out of the second booster during a press conference Sunday night, where he said that anyone over the age of 60, as well as  medical staff who had received their first booster four months ago or more, could get inoculated. 

“The decision was made after consulting with various experts,” Bennett said. “The significance is great; we will have a new layer of protection.”

He added that the country’s policy of booster shots has kept citizens healthy with per capita death rates among the world’s lowest – as compared to the United Kingdom, where the mortality rate is 50 times greater, Germany 100 times and in the United States, 130 times higher.

Israel was the first in the world to approve a third jab despite international criticism,  including from the World Health Organization, which has repeatedly  warned rich countries  against hoarding shots – saying that leaves variants to flourish in low-income countries, prolonging the pandemic.  

“We must not be complacent,” the prime minister warned. “Everyone who is entitled to a fourth dose, get vaccinated.”

In his own announcement, the country’s Healthy Ministry Director-General Nachman Ash said the move was made “in light of the increase in morbidity,” as new daily cases on Monday topped 6,500 and the prime minister warned of 50,000 new daily cases in the coming weeks. That would be a per capita rate about equal to Denmark, one of the European countries seeing exceptionally high COVID infection rates. 

Still no evidence of fourth dose preventing infection 

But local and international scientists and doctors were quick to highlight that there is still no evidence of the effectiveness of a fourth dose in preventing infection, serious disease or death. 

“The decision must be accompanied by a scientific evaluation by an independent body,” charged the Israeli Association of Public Health Physicians in a statement. “Resources must be directed first and foremost to [encourage the public] to complete their first, second and third vaccines whose benefit is clear and scientifically proven.”

Despite racing ahead of the world on vaccine roll-out, Israel’s overall vaccination rate for people who have received their first two doses now lags behind many other nations, with only 60% of the country vaccinated with two jabs within the last six months or three shots, and some 700,000 entirely unvaccinated.  

Other countries will be closely eyeing moves

As in other virus waves, Israel’s moves will be closely eyed by other countries that are anxious to blunt the full force of the new Omicron variant – which is far more infectious – even if it is also supposedly less deadly.  

That, in the face of mounting evidence from around the world that the degree of protection offered by mRNA vaccines against SARS-CoV2 in general, and against Omicron in particular, declines sharply four to six months after vaccination. Laboratory tests have, however, suggested that even lower levels of neutralizing antibodies, as well as continued T-cell immunity, may still provide protection against the development of serious disease. 

Chile also announced last month that it would offer citizens a fourth coronavirus vaccine dose, also starting with those who are at highest risk of infection or developing severe disease, those shots are not expected to begin until February and they are being given only after six months have passed from the previous jab.

Brazil also has approved a fourth shot, but only for the immunocompromised. 

Giant experiment on safety and efficacy 

Now Israel’s new campaign, which will be tracked by its  national digitized system of healthcare records, and research teams, is expected to provide real-time information on the efficacy of yet another booster against Omicron – in what amounts to a large-scale national clinical trial. 

There is also still no evidence as to the safety of a fourth shot – although most health experts believe that the mRNA vaccines will not cause any short- or long-term harm. 

Sheba Medical Center at Tel Hashomer last week launched a fourth shot trial in late December of around 150 healthcare workers to see how much an additional COVID shot raises a person’s antibody levels and if there are any negative effects, but no concrete data has been released yet.

On Sunday night, the hospital said that out of 154 people who received the jab, 80% reported mild reactions at the point of injection – similar to after the third dose. Some 45% of recipients experienced fever, weakness, muscle aches or headaches – symptoms that in most cases passed within 24 hours. 

“From these data, it appears at this stage that the fourth vaccine profile is as safe as the previous vaccine doses,” said Dr. Gili Regev-Yochay, director of the Infectious Disease Epidemiology Unit at the hospital who is running the new study. 

Local experts argued that pre-existing vaccine protection could decline to almost nil within another month 

The decision to move to a fourth jab was taken following a December 21 meeting of Israel’s national Pandemic Response Team, when experts warned that within a month’s time, Israel’s population would be as vulnerable to Omicron as they had been to the initial COVID-19 outbreak prior to any vaccination whatsoever.

Another team of researchers told the committee that a third booster shot was not even enough to halt Omicron as its effectiveness against the variant would decline from 75% to 25% after month four. 

The Ministry of Health team ultimately voted in favor of the fourth shot – just 10 days after it had shot down the move. But it took Ash another week and thousands more Omicron cases to give his final approval. 

Other critics still maintain, however, that the Pfizer vaccine was never intended to ward off infection, but to prevent severe disease and death. And it appears that the second dose, and certainly the third shot, does a decent job of that already – even in the face of Omicron. 

Moreover, the Omicron variant causes less serious disease in general than its Delta predecessor, according to all studies and predictions. 

Finally, the Omicron wave appears to be short-lived. Already this week, South African health officials announced that they believed the country had passed the peak of the wave, with new cases dropping by nearly 30%.

But until Sheba’s fourth dose trial is over or enough Israelis over the age of 60 get the jab, the decision to give a fourth dose is just a shot in the dark. 

“In the coming days, we will report preliminary findings regarding the initial increase in antibodies and immunity within a week of vaccination,” Regev-Yochay said. 

Image Credits: Clalit Health Fund , G. Ginsberg.