Health officials are analyzing two different trends in coronavirus cases in Israel: those who test positive, and those who develop severe cases.
https://www.jpost.com-By MAAYAN JAFFE-HOFFMAN
Israelis walk the streets of Tel Aviv, July 6, 2021.(photo credit: MARC ISRAEL SELLEM)
Israel’s health officials must stay focused on how many Israelis will develop serious cases of COVID-19 and not on the percentage of vaccinated people who could or could not simply contract the virus, top health officials told The Jerusalem Post.
On Monday, the Health Ministry released new data that showed that the Pfizer vaccine had decreased in its effectiveness against stopping people from catching coronavirus to as low as 64%.
The news spawned hundreds of articles and posts on social media, calling into question both how Israeli health officials determined this percentage and what this information really means for the Israeli public and the world.
The ministry received so many questions about its report that on Monday it sent out a further explanation: “Vaccine efficiency means what percentage of morbidity – or hospitalizations or mortality – can be prevented by the vaccine,” the ministry said.
When a vaccine is 100% effective, there will be no cases of disease among the vaccinated. When a vaccine is not effective at all (0%), the morbidity rate will be the same among those who are vaccinated and unvaccinated.
The ministry analyzed the data using a statistical model that compares the number of infections among vaccinated versus unvaccinated in a given period, while accounting for external but influential factors, such as age of infection and week of outbreak.
But some health officials, such as Sheba Medical Center’s Infectious Disease Epidemiology Unit Director Dr. Gili Regev-Yochay, have said that the “64% is not that relevant.”
That’s because there are two curves. On one is the number of people who test positive for coronavirus. On the second is the number of people who develop severe cases of COVID-19 – only this number threatens to increase mortality and break the hospital system.
“Obviously we don’t want people testing positive for coronavirus in Israel,” said Dr. Arnon Shahar, head of the COVID-19 Medical Task Force for Maccabi Healthcare Services. “But what we really don’t want is the number of severe cases to go up. We want to separate these two curves as much as we can.”
So far, Israel is seeing two separate curves. While on Tuesday some 500 people were diagnosed as positive – the highest number of new patients Israel has seen since March 26 – the number of serious cases stood at 38.
The number of serious patients increased by three between morning and evening on Tuesday, but had declined by three between Monday evening and Tuesday morning – meaning it is largely stable.
Although perhaps it’s too preliminary to determine for certain, Israel’s trend line seems to be almost mirroring what is happening in the United Kingdom, where the Delta variant has been around a little longer.
The UK decided on Monday to substantially reduce restrictions beginning on July 19 even though the number of active coronavirus cases in the country is high. This is due to the number of people hospitalized or COVID-19 deaths remaining stable.
So far, more than 45.3 million Brits have received at least one dose of a coronavirus vaccine – about 85% of the adult population.
That does not mean that Israel will not have its share of symptomatic patients.
“As long as we see positive patients in Israel, we are going to see both more asymptomatic and symptomatic, including those who are vaccinated. Sometimes, vaccinated patients will have symptoms and a certain percentage of vaccinated will even become severely ill,” Shahar said. “This does not mean that the vaccine is not working. We know that the vaccine has great efficacy against severe disease, but not 100%.”
If there were 100 people in an institution and 90 of them were vaccinated and there was a measles outbreak, it is likely that all 10 unvaccinated people would get the virus. However, it is also likely that around 15 vaccinated people would catch measles, too. That’s because the vaccine’s efficacy is only around 95%.
“Anti-vaxxers would say, ‘see, even more people who were vaccinated got measles than non-vaccinated,’” Shahar said as an example. “But the reality is that if no one was vaccinated, it is likely that all 100 of them would have gotten sick, among them some with severe disease.”
He also said that if everyone was vaccinated, it is possible and even likely that there would have been no disease at all because herd immunity would have been achieved.
Israel cannot eradicate COVID-19 unless everyone is vaccinated and, so far, the coronavirus vaccines are not approved for use in children under 12.
“We cannot get herd immunity as long as we are not vaccinating the kids,” Shahar said.
As such, “it was expected and is expected” that there would be new cases of coronavirus.
“We do not need to be alarmed or panicked,” Shahar said. “We do need to be disturbed and understand how we can contain these outbreaks.”
He said the Delta variant started in India because the country had a big coronavirus outbreak. During spikes, when the virus is rapidly spreading, it is also often mutating, and sometimes it makes new variants of concern.
“We need to contain the virus so as not to have big spikes among the unvaccinated and then pass the virus onto the vaccinated in the form of a new variant,” he said, advocating for restrictions against mass gatherings among unvaccinated people.
Those who are vaccinated, however, should be able to continue with their normal routines.
Furthermore, in a new study conducted at Sheba Medical Center in collaboration with Harvard University, it was found that the coronavirus vaccines not only make people less susceptible to catching the virus but also reduce their ability to spread it – both after the first and the second dose.
“The findings showed that the viral load was significantly lower among vaccinated people who became ill compared to unvaccinated people who became ill,” Regev-Yochay said. “The lower the viral load, the smaller the ability to infect.”
The study, which was conducted during the peak of the Alpha, or British variant, was published over the weekend in the peer-reviewed medical journal the Lancet, and involved some 9,650 Sheba employees. Regev-Yochay said that she would expect similar results with regards to the Delta variant – that people who are vaccinated are less likely to infect others.
The findings of the study also showed that the effectiveness of the Pfizer vaccine in preventing asymptomatic cases stood at 83% – 20% more effectiveness than what the Health Ministry reported about the vaccine’s effectiveness against the Delta strain.
And that is not cause for panic?
“Sixty-four percent is probably not an accurate number,” Shahar told the Post. “This is just an observational number.”
He said the 64% is a preliminary percentage based on a small number of positive cases in recent weeks. In addition, he said there is a tremendous amount of data bias. For example, the Health Ministry only started requiring vaccinated people who came in contact with infected people to be tested for coronavirus. So, how does the ministry know if there were not equally as many asymptomatic cases before?
What is understood is that as of now, the vaccine is at least 90%-95% effective against stopping hospitalization or serious disease – the metric that at least these health professionals believe should be used in determining policy.
There are still several hundred thousand eligible Israelis, even some who are high risk, who have not yet been inoculated.
“The most important thing with the Delta strain is that those people go – that they run and get vaccinated,” Regev-Yochay said.