Omicron booster vaccine reduces COVID hospitalization, death among elderly

The latest booster vaccine adapted for the Omicron strain has been shown to reduce hospitalization from COVID-19 complications by 72% and deaths in people aged 65 and over by 68%, according to a comprehensive study by the Clalit Research Institute.

The study by researchers for Clalit Healthcare Services – Israel’s largest health fund, has just been published in the prestigious journal Lancet Infectious Diseases under the title “Effectiveness of a bivalent mRNA vaccine booster dose to prevent severe COVID-19 outcomes: A retrospective study.”

Just last week, the US Food and Drug Administration (FDA) and the US Centers for Disease Control (CDC) approved a “bivalent,” reformulated second booster dose adapted to Omicron for people aged 65+ and those of all ages who are immunosuppressed. Relevant Americans will be able to get this booster immediately.

The bivalent vaccine targets the original variant of the coronavirus as well as variants BA.4 and BA.5 that were the most common last summer, but BA.4 and BA.5 were quickly replaced by newer versions.

According to reports from the US government, health officials are also phasing out the original vaccine formulas created by Pfizer-BioNTech and Moderna, canceling their authorizations in the US. Now, people who were never vaccinated can get just one dose of the reformulated, or “bivalent,” COVID shot to be considered vaccinated instead of two shots of the previous vaccines.

What is the bivalent Omicron vaccine's efficacy?

Using advanced statistical methods, the team from Clalit’s community medicine department analyzed the data of patients in the health fund to examine the efficacy of the bivalent Omicron vaccine and whether it protected older Israelis from hospitalization and mortality.

They worked in collaboration with the Faculty of Health Sciences at Ben-Gurion University of the Negev (BGU) in Beersheba and a lab at Sapir College near Sderot. The authors were Ruslan Sergienko, MHA, Michael Friger, Tanya Beckenstein and Hadar Duskin-Bitan.

At the end of 2022, the Health Ministry recommended that older Israelis and those with weak immune systems be vaccinated with a vaccine adapted to the Omicron strain, provided that at least three months had passed since receiving the last vaccine dose or recovery from the infection.

When the bivalent vaccine was approved by the FDA, the study was carried out here between September 27, 2022 and January 25, 2023. The researchers reviewed data on 569,519 Clalit patients. The research method included multivariate adjustment for a variety of mortality risk factors so as to neutralize possible biases that could arise from differences in age, gender, socioeconomic status or co-morbidity among the populations. This was the largest group size ever examined for this, allowing an accurate assessment of the relationship between receiving the vaccine dose and hospitalization and mortality rates resulting from COVID-19.

The average age of the study population was 75. At the end of the study period, 24% of this population received the new vaccine. Compared to a control group of people who were not vaccinated, the recipients showed a 72% reduction in hospitalization rates and a 68% drop in mortality.

Dr. Doron Netzer, head of Clalit’s medical department, said that after the adapted vaccine was approved in an emergency procedure by the FDA and CDC without studies carried out, so there was uncertainty about its usefulness. “Our research is the first in the world on the bivalent Omicron vaccine. We showed that it is an important addition for protecting at-risk populations.”