Israeli data suggests mass vaccinations led to drop in severe Covid cases, CDC study finds

Data from Israel, which vaccinated the overwhelming majority of its elderly population with the Pfizer Covid-19 vaccine, suggests that mass vaccinations have kept people from getting seriously ill, according to a new study from the Centers for Disease Control and Prevention.

While clinical trials have shown the Pfizer-BioNTech vaccine to be 95% effective in preventing Covid-19, Israeli data offers early insight into the effectiveness of the vaccine in an uncontrolled, real-world setting.

The study, which was published in the CDC’s Weekly Morbidity and Mortality Report on Friday, found that among the part of the Israeli population that has received the most vaccinations, the percentage of patients requiring ventilation has declined significantly, which suggests a reduction in serious illnesses.

“Taken together, these results suggest a reduction in severe COVID-19 rates after vaccination,” wrote researchers from Ben-Gurion University in the Negev, Tel Aviv University and Maccabi Health Services.

Israel launched its national immunization campaign in December, prioritizing people 60 years of age and older, health workers and people with co-morbidities. As of February, the researchers said, 84% of the population aged 70 and over had been fully immunized with the two-dose Pfizer-BioNTech vaccine. Only 10% of the population under 50 had been vaccinated around the same time, according to the researchers.

Researchers compared the number of Covid-19 patients aged 70 and older who needed a mechanical ventilator to those under 50 who needed a ventilator. Researchers said they used the need for a ventilator, a medical device used to help patients breathe, to measure severe Covid-19.

Between October and February, the number of patients aged 70 and over who needed a ventilator decreased. At the same time, the number of people under the age of 50, a population that was usually unvaccinated, who needed a ventilator increased, according to the study. The country began giving injections to mostly elderly people on December 20, with a second round of gunfire three weeks later.

The researchers noted some limitations of the study. Israel implemented a strict national stay-at-home order on January 8, weeks after the start of the vaccination campaign, which could have resulted in a decrease in the number of critically ill patients who would have needed ventilators. The introduction of new variants of the coronavirus could also have affected the data, they said.

The researchers said their results are preliminary, “significant evidence for the effectiveness of vaccines in preventing severe cases of COVID-19 nationally in Israel.”

“Receipt of COVID-19 vaccines by eligible people can help limit the spread of disease and potentially reduce the onset of serious disease,” they wrote.