Vaccine efficacy 80%-88% for chronic disease carriers

The Pfizer coronavirus vaccine has also proven to be effective among chronic disease carriers, a study conducted by the Clalit Health Fund and published in the New England Journal of Medicine has demonstrated.

“This paper is a direct continuation of the large study we published in the same journal a few weeks ago,” said Prof. Ran Balicer, Clalit’s chief of innovation. “Recent results suggest that the vaccine is effective and protects against disease and serious illness at a higher rate than we thought, and is also very effective in patients with chronic diseases. However, we could already begin to notice in the previous study [that] the protection is slightly reduced in those suffering from a number of significant background conditions.”

The study examined data from some 1.4 million customers of Clalit, Israel’s largest healthcare provider, which assists some 4.7 million people. The data was collected between December 20 and February 1.

Each vaccinated individual was matched with an unvaccinated individual from similar circumstances to act as a control.

Three different periods were considered, as explained in the paper: Days 14 through 20 after the first dose of vaccine, days 21 through 27 after the first dose (administration of the second dose was scheduled to occur on day 21 after the first dose), and day seven after the second dose until the end of the follow-up.

At the end of the follow-up period, as far as the general population is concerned, the inoculation proved to be 96% effective in preventing symptomatic morbidity and 95% in preventing severe morbidity. In the previous study, the rates were 94% and 92%.

Besides providing evidence for the efficacy of the Pfizer vaccine on the general population, the research also focused on specific groups.

Moreover, researchers saw that the vaccine was 92% effective in preventing symptomatic infections in people over 70.

The study also found that the vaccine was still highly effective for those vaccinated carrying other risk factors, albeit slightly less: some 84% for those who underwent an organ transplant, 80% for heart disease carriers, 80% for patients with chronic kidney disease, and 86% for patients with diabetes. In addition, the vaccine was highly effective – 96% – in overweight individuals.

“These are very encouraging findings as they indicate that a large majority of the expected cases among these patients will be prevented by the vaccine despite their background diseases, although they still present a slightly higher residual risk of infection,” Balicer said. “We can draw two main conclusions: additional emphasis should be placed on the great importance for this population to be vaccinated at any age, and also on the need for these patients to continue to engage in preventive behavior when they are in circumstances where there is a significant risk of infection. Fortunately, the risk of such circumstances in the State of Israel in recent months has been steadily declining.”

Israel currently has about 2,000 active coronavirus cases, down from over 70,000 at the peak of the pandemic in January. For the past several days, the country has been registering less than 200 new daily cases.