The fourth coronavirus vaccine resulted in a 78% decrease in COVID-19 related deaths in adults aged 60-100, according to a new study by Clalit Health Services.
"Significant" reduction of COVID-19 related deaths
The study, conducted by Clalit, Sapir College and Ben-Gurion University of the Negev, examined the effect the second booster shot had on mortality rates of the population eligible to receive it in Israel. The research was led by Dr. Ronen Arbel, a health outcomes researcher at Clalit Health Services and Sapir College. The paper is currently awaiting peer review.
At the time of its introduction, the fourth vaccine was controversial due to a lack of epidemiological and large-scale clinical evidence on the efficacy of a second booster shot. As a result, uptake of it among eligible populations was significantly lower than it had been at the start of the first booster distribution.
However, the study’s authors are hoping that with the release of the new information in the study, showing that the fourth vaccine did significantly reduce COVID-19 related deaths, people who have been hesitant up until now will decide to be inoculated with a second booster shot.
The researchers examined data from all 563,465 Clalit Health Services members eligible for the fourth vaccine. The median age of the participants was 73 years old, and 53% of participants were female.
The study population was divided into two groups: those who had received a second booster shot and those who had only received the first one.
Participants were only grouped under the “second booster” category if at least seven days had passed since receiving the dose. If any participant contracted the virus within seven days of receiving the second booster, they were excluded from the study.
Out of the total number of people counted in the study, 58% (328,597) received the second booster shot within the 40-day period of January 10-February 20, 2022, when the research was conducted. Uptake was notably higher among participants with a higher socioeconomic status but lower within haredi (ultra-Orthodox) and Arab populations, the researchers said.
During that time period, the research group recorded 232 coronavirus-related deaths in people who had received just the first booster shot and 92 deaths in participants who had received the second booster shot.
The aim - "to reduce hospitalizations and infections"
Of the 92 deaths recorded in participants who had been vaccinated four times, five occurred in people aged 60-69, 22 were in people aged 70-79, and 65 were in people aged 80-100. Among participants who had received three vaccines, 32 deaths occurred in people aged 60-69, 51 in people aged 70-79 and 149 in people aged 80-100.
AMONG THE older population who received a first booster dose at least four months prior to the study, mortality due to the Omicron variant was significantly lower for those who had received an additional booster dose.
However, the 78% reduction in mortality rates from the fourth vaccine was still lower than the 90% mortality-rate reduction in elderly populations during the Delta wave as a result of the third vaccine, the study showed.
The goal of the study was to increase uptake of the second booster within Israel’s 60-plus population, as well as encourage other countries to implement the use of an additional vaccine in vulnerable populations, Arbel told The Jerusalem Post.
“The objective of the second booster, and the policy now, is to reduce hospitalizations and infections,” he said. “Our objective is to reduce severe diseases and mortalities in people above the age of 60.”
“And this is the policy in Israel,” he added. “The priority should definitely be to complete the vaccination, or the second booster vaccination, of citizens over 60.”
The limitations of the study
Despite the success of the study, there were several limitations, as noted in the paper. The primary limitation is that it was conducted over a relatively short period of time – 40 days.
However, the infection rate in Israel from the Omicron variant rose to be the highest in the world during that period. In addition, almost no social-distancing restrictions were implemented in the country during the duration of the Omicron wave.
Therefore, “exposure to SARS-CoV-2 was substantial, and accordingly, the number of Covid-19 severe events was sufficient to demonstrate significant associations between the second booster dose and reduced Covid-19 mortality rates,” the study said.
Furthermore, the study was based on hospital records regarding the cause of death. However, because most medical centers test every patient for the virus upon admittance, the participants possibly died from other causes, but COVID-19 was still written as a factor in death since they had been positive with it at the time of their passing.
Nevertheless, “a recent study analyzing excess deaths during the Covid-19 pandemic demonstrated that the Israeli rate of excess death is in accordance with its Covid-19 mortality reports,” the researchers said, adding that this possibility should not have significantly altered the results of the study.
THE SUBJECT of the fourth vaccine is a much-contested topic, Arbel told the Post, citing an FDA meeting on the topic scheduled for next week as an example.
“They’re discussing who they should approve it for,” he said. “Should it be for over 60, over 65? The UK is already giving it to people over the age of 75. And still, in Israel, about 40% of [eligible] people have not received their second booster. So that’s by far the most important priority.”
Asked why he thinks there is so much hesitation regarding whether to receive the second booster shot, Arbel cited the lack of evidence of success at the time of its introduction as the primary reason.
“People said, even physicians who spoke to me, ‘Why should we get vaccinated when there’s no proof that it has any effect?’ And now we have some serious proof, on the very most important endpoint, which is mortality,” he said.
“I totally understand people who said there was no proof, like with the first booster, because Israel is always the first to do these things,” he added. “With the first booster, maybe there was some more evidence. But for the second, [there was] practically no evidence in the world.”
“So it was a reasonable thing to say, ‘Let’s wait for evidence,’” Arbel said. “But now we have evidence. So yes, we hope that this evidence changes things. People are already saying they are going to get their second boosters now. This is what we hoped would happen, and we hope [this study] will contribute to that.”