New study shares preliminary data on Pfizer vaccine’s effectiveness in Israel

Vaccination efforts against the coronavirus disease 2019 (COVID-19) pandemic have started in many countries, including the United States, United Kingdom, and Israel.

Currently, Israel has the highest rate of vaccinated people per capita, with 45.3 percent and 29.7 percent of the population having received the first or the second dose, respectively.

In a new study, published on the preprint medRxiv* server, researchers at the Weizmann Institute of Science and the Technion, Tel Aviv University and the Israeli Institute of Technology showed that by mid-January, the number of COVID-19 cases and hospitalizations began to decline with a larger and earlier decrease among older people.

The team noted that the vaccination campaign in the country was effective in preventing transmission of the virus, especially among high-risk populations in Israel.

Israel’s vaccination efforts

To stem the tide of the current pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an effective and safe vaccination campaign is needed. The BNT162b2 vaccine, developed by BioNTech and Pfizer, is a lipid nucleoside-modified messenger RNA (mRNA) encoding the SARS-CoV-2 full-length spike 1. Also called the “Pfizer vaccine”, it has been approved for use by regulatory bodies in many countries worldwide.

On December 11, 2020, the U.S. Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for the use of the BNT162b2 vaccine. The results from a phase III randomized placebo-controlled trial demonstrated that a two-dose regimen induced a 95 percent protection against SARS-CoV2.

Israel rolled out its vaccination efforts on December 20, 2020, focusing on high-risk populations, including people who are older than 60, nursing home residents, healthcare workers, and patients with severe comorbidities.

Evaluating the real-life effect and efficacy of vaccines is crucial. This can be conducted by assessing the real-life impact of vaccination programs at a population level, called vaccine impact (VI), or by evaluating the vaccine’s direct protective effects at the individual level, termed as vaccine effectiveness (VE).

The study

In the study, the researchers conducted a retrospective analysis of data between March 2020 and February 2021, which came from the Israeli Ministry of Health (MOH). The data included information on the age, sex, date of positive SARS-CoV-2 polymerase chain reaction (PCR) test, data of hospitalization, clinical state, and date of death for those who succumbed to the illness.

Also, the team used data on national vaccination, including the number of daily vaccine doses, separated into first and second doses and administered in each city by age groups. Overall, the team reported that a total of 3.42 million people who were vaccinated and over 684,000 PCR positive individuals were included in the analysis.

In analyzing the data, the team considered real-life effectiveness on the national level, between cities, and in higher geographical-resolution termed geographical statistical areas.

The team found that in the past week, an estimated one and a half months after the start of the vaccination campaign in Israel, there was a 49 percent drop in critically ill patients compared to 21 days ago. About 80 percent of people who are over 60 years old were already vaccinated at that time.

Even though many factors may have driven these results, the team noted some observations suggesting that these patterns are influenced by the vaccination campaign. First, the decline was tied to older individuals, who were prioritized to receive the vaccines first. Next, the effect was greater in cities and GSAs where a higher proportion of individuals were vaccinated earlier.

The researchers also noted that areas with higher infection rates and lower socioeconomic status have lower vaccination rates, even if there is a vast availability of vaccines.

“Further effort should be made to encourage these populations to vaccinate and make the vaccines even more easily accessible for them,” the researchers noted in the paper.

We note that exact individual-level efficacy numbers cannot be deduced from our analysis and that due to all of the above issues, our results may be consistent with efficacies that are either lower or greater than those reported in the original clinical trial,” they explained.

Hence, the team concluded that the study shows the first signs of the real-life effectiveness of a national vaccination campaign. Though preliminary, the study findings are important in promoting the use of vaccines to stem the ongoing global health crisis.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Angela Betsaida B. Laguipo

Angela is a nurse by profession and a writer by heart. She graduated with honors (Cum Laude) for her Bachelor of Nursing degree at the University of Baguio, Philippines. She is currently completing her Master's Degree where she specialized in Maternal and Child Nursing and worked as a clinical instructor and educator in the School of Nursing at the University of Baguio.