Vaccine effectiveness in preventing serious COVID-19 infection among the elderly has fallen to 50 percent, according to new Israeli figures, but some prominent experts are saying the data shouldn’t be taken seriously.

The Pfizer-BioNTech coronavirus vaccines were wowing Israelis with sky-high effectiveness rates until the rise of the Delta variant.

But according to data recently raised at a top-level Health Ministry meeting, the immunization’s effectiveness in preventing serious illness is now at 80% for the general population and 50% for the elderly.

Israel’s national research body for epidemiology, the Gertner Institute, conducted the research, and Dr. Amit Huppert from its bio-statistical unit told The Times of Israel that policymakers should pay attention.

The government “should not be panicked but should take the data seriously, as it’s a warning that should not be ignored,” he said. “Most of us did not believe a month ago we could be in this situation.”

He added that policymakers didn’t pay enough attention to data on the Alpha variant which arose in Britain and spread quickly in Israel in early 2021.

But as the numbers ignite concern among Israelis, even the government’s top expert adviser on coronavirus questioned their integrity. The approach taken could result in a “horribly skewed” outcome, argued Prof. Ran Balicer, chairman of Israel’s national expert panel on COVID-19.

“Any attempt to deduce severe illness vaccine effectiveness from semi-crude illness rates among the yes or no vaccinated is very, very risky,” he maintained.

Infectious diseases doctor Yael Paran told The Times of Israel that she can’t reconcile the figures on serious illness with the much more rosy reality she sees.

“What we see in our hospital and around the world don’t support this,” she said. “I think the figures are exaggerated.”

Huppert acknowledged that the statistics have their limitations. “These are early estimations based on small numbers, and there are all kinds of biases in the numbers,” he said. But he insisted that despite the caveats, they still have great relevance.

But Paran, a senior physician at Tel Aviv Sourasky Medical Center, argued that the problem with them runs deep, and the definition of “serious illness” has become misleading. It is used for patients whose oxygen saturation drops, which was a good indicator pre-vaccination as it signaled deterioration. But for vaccine-protected patients it is often a brief state that doesn’t signal significant deterioration, she said.

“Take a patient who is in my hospital now as an example,” she said. “He is in his 80s and classed as severe, but only because he had a mild drop in saturation. It was something that any other disease would cause, and which we’re treating well with steroids, but he is classed as a serious case.”

Dr. Dvir Aran, an expert in health statistics from the Technion – Israel Institute of Technology, said he is concerned the Health Ministry is using “bad research” and allowing it to be presented without context.

“The problems aren’t with the vaccine, they are with the data,” he said, branding as “false” the conclusions in the latest data and other research on how well the vaccine prevents infection.

The research process “skews the results to make the vaccine seem less effective than it is,” he told The Times of Israel.

Health Ministry data released in early July said the vaccine’s effectiveness in preventing infection, which was over 90% pre-Delta, is now at 64%.

Such numbers are crunched by comparing infection rates and illness rates in vaccinated and unvaccinated people, to measure the vaccines’ protection.

However, Aran said that people who decline to get vaccinated are, in disproportionately high numbers, people who are skeptical about the existence or danger of COVID-19, distrustful of health services, and overall relatively unlikely to get tested.

“We are probably only finding, through testing, a minority of instances when unvaccinated people get the coronavirus — and as the statistics rely on a comparison this makes effectiveness for the vaccinated seem much lower,” Aran said.

When it comes to the latest data on serious illness, Aran said the number of people factored into the calculations is so small that small margins of error can cause a major impact on the bottom line. The research process is not conducive to accurate conclusions, he argues. The overall number of seriously ill in Israel is 63. The slice of the adult population that is unvaccinated is small, and for those over 60, who generate the most troubling statistic, it is tiny.

“The number of unvaccinated over-60s is actually smaller than we think. Some who appear to be unvaccinated are actually dead, as it can take time to record deaths; others are protected by recovery from the illness,” commented Aran.

He believes that statistics falsely pointing to poor vaccine performance are harmful, because they make people more reluctant to take the shots.

“This hurts compliance of people with vaccinations,” he said. “If you’re saying to the public that vaccines work less, it hurts enthusiasm for them.”

Source: Nathan Jeffay – TOI