The fourth dose of the coronavirus vaccine is effective in protecting the elderly against the Omicron variant and lowers their risk of death by 72% compared to those who received only three doses, according to a new study conducted by Tel Aviv University and Ben-Gurion University of the Negev in collaboration with the Health Ministry.
The study, published in the peer-reviewed JAMA Internal Medicine journal, found that elderly recipients of the fourth dose were 34% more protected against infection than those who received only the third dose at four months previously. Recipients of the fourth dose were also 64-67% less likely to be hospitalized for mild to moderate and severe illness.
The study
Over 40,000 elderly residents took part in the study, including about 24,000 who received the fourth dose and about 20,000 who received the third dose. The participants were residents of about 1,000 geriatric institutions, nursing homes and assisted living facilities that are part of the Health Ministry’s Senior Shield system, according to Prof. Khitam Muhsen of the School of Public Health at Tel Aviv University.
"These are significant data, because the Senior Shield population is one of the groups who suffer the most severe morbidity from the coronavirus, at a much higher rate than the general population," said Muhsen.
"We assume that the fourth dose of the vaccine boosted the level of neutralizing antibodies, which conferred cross-protection against the Omicron variant. Our study points to the significant benefit of administering the fourth dose of the vaccine, and confirms that the policy adopted by the State of Israel was the correct one. The decision to vaccinate at-risk populations with the fourth dose was a wise choice that saved a lot of human lives.”
“This is a groundbreaking and innovative study based on a database of the elderly population in care facilities," said Muhsen, adding that the study had participants undergo both routing and "blind" COVID tests, regardless of whether or not they received the vaccine, in order to lower the bias caused by the fact that most people who go to be tested or vaccinated tend to exhibit positive health behaviors.
“The study indicates that giving booster shots and raising the level of antibodies through a vaccine based on the original COVID-19 strain provides significant protection against the onset of serious illness even after infection with new variants, including those that are very different from the original, such as Omicron," added Prof. Dani Cohen of the School of Public Health at Tel Aviv University.
"Giving booster shots and raising the level of antibodies through a vaccine based on the original COVID-19 strain provides significant protection against the onset of serious illness even after infection with new variants."
Prof. Dani Cohen of the School of Public Health at Tel Aviv University
“The task of protecting institutions for people living outside of the home is a very important aspect of the Health Ministry’s Senior Shield program," explained Prof. Nimrod Maimon.
"The database that the project has built and accumulated about the institutions and their residents has allowed for rapid and effective vaccination campaigns, which have yielded dramatic results in curbing illness from the coronavirus amongst these populations. The impressive results of the program have received widespread international praise, with health authorities from many countries around the world seeking to learn from the Senior Shield program.”