Exploring safety through a 4th dose of BNT162b2 in opposition to SARS-CoV-2 Omicron variant in Israel

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In a latest research posted to the medRxiv* preprint server, researchers from Israel assessed the effectiveness of a fourth dose of BNT162b2 vaccine (Pfizer-BioNTech) in opposition to confirmed an infection and extreme sickness as a result of coronavirus illness 2019 (COVID-19).

Study: Protection by 4th dose of BNT162b2 against Omicron in Israel. Image Credit: Yuri Dondish/ShutterstockExamine: Safety by 4th dose of BNT162b2 in opposition to Omicron in Israel. Picture Credit score: Yuri Dondish/Shutterstock


COVID-19, brought on by extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) an infection, has globally triggered over 5.6 million deaths. Regardless of sturdy COVID-19 vaccines developed inside a brief span and administered throughout many international locations, variants of concern (VOCs) have emerged within the ongoing pandemic. Of the VOCs, the most recent is the Omicron variant, which was first recognized in  South Africa in November 2021.

Omicron has elevated transmissibility and virulence. It has immune evasive properties, decreasing the effectiveness of public well being and social measures, in addition to the accessible diagnostics and vaccines.

In Israel, as of late December 2021, the Omicron variant was quick spreading and inflicting elevated infections and extreme sickness. The third vaccine dose was administered greater than 4 months in the past, and the results of immune safety have been waning off.

In an effort to handle these challenges as a result of Omicron variant and to scale back the load on the healthcare system, the Israeli authorities on January 3, 2022, started administering a fourth dose of the BNT162b2 vaccine firstly to folks aged over 60 years and high-risk populations in addition to healthcare staff, who had acquired a 3rd dose of vaccine not less than 4 months earlier.

Utilizing knowledge from the Israeli Ministry of Well being nationwide database, the researchers within the current research assessed the real-world effectiveness of the fourth dose in decreasing the confirmed COVID-19 circumstances and extreme sickness.

Concerning the research

To find out the effectiveness of the fourth COVID-19 vaccine dose, the researchers in contrast it with the noticed efficacy  of the third vaccine dose. Particularly, they in contrast the speed of the confirmed COVID-19 circumstances and extreme sickness between 1) these people who had acquired a fourth dose not less than 12 days earlier, 2) those that had acquired solely three doses, and three) these people, 3 to 7 days after receiving the fourth dose.

The management group included people who have been eligible for the fourth dose however had not but acquired it. To account for unmeasured confounding variables, the researchers included a second management group of people for whom 3-7 days had handed since receiving the fourth dose.

This management group included the identical people who have been assessed 12 days later (the therapy group) – solely at an earlier time interval when the fourth dose was not anticipated to be efficient. As a result of the vaccine is anticipated to take impact solely after 3-7 days following the vaccination, a longitudinal comparability with the impact after 12 days of vaccination was additionally noticed right here.

The researchers calculated the whole variety of person-days in danger, and the incidence charge of the SARS-CoV-2 an infection and extreme sickness as a result of COVID-19 within the management teams and the therapy group. The an infection was confirmed both by state-regulated speedy antigen checks or by polymerase chain response checks (PCR). The extreme sickness as a result of COVID-19 was outlined utilizing the Nationwide Institutes of Well being (NIH) definition, which included a resting respiratory charge of greater than 30 breaths per minute, oxygen saturation of lower than 94% whereas respiration ambient air, or a ratio of partial strain of arterial oxygen to fraction of impressed oxygen of lower than 300.

The research interval was from January 15 to January 27, 2022, extracting knowledge concerning the SARS-CoV-2 an infection and extreme sickness as a result of COVID-19. It’s to be famous that in this era, the infections have been overwhelmingly brought on by the Omicron variant. This research began 12 days after the beginning of the vaccination marketing campaign (January 3, 2022).

Based mostly on a set of exclusion standards, akin to those that died earlier than this research, people who have been overseas, and people who acquired a vaccine dose aside from Pfizer-BioNTech, and many others. the research included a complete of 1,138,681 contributors. These contributors have been 60 years of age or older and had acquired three doses of BNT162b2 not less than 4 months earlier than the beginning of the research interval.

Whereas the Israeli Ministry of Well being and Pfizer have a data-sharing settlement, the researchers identified that solely the ultimate outcomes of this research have been shared.

Evaluation of the research inhabitants

The researchers introduced the demographic and medical traits of the completely different cohorts on this research. As a result of this research concerned dynamic cohorts (folks might transfer between the cohorts), the proportion of person-days in danger for confirmed an infection was calculated as a substitute of the variety of people.

In comparison with those that didn’t obtain the fourth dose, the person-days have been discovered to incorporate these over the age of 80 and enriched with the final Jewish inhabitants. People with out the fourth dose had twice the chance days in comparison with the fourth-dose vaccinated ones and likewise had many confirmed infections and extreme sickness circumstances.

Safety conferred by the fourth COVID-19 vaccine dose

The incidence charge for confirmed an infection within the group of people that didn’t obtain the fourth dose was twice the individuals who acquired the fourth dose earlier than 12 days or longer. Equally, the speed of extreme illness was diminished by an element of 4 within the individuals who acquired the fourth dose in comparison with those that didn’t obtain it.

Throughout the group of people that acquired the fourth dose, the outcomes for incidence of infections and extreme sickness have been equally diminished within the group of people that acquired the fourth dose earlier than 12 or extra days in comparison with those that acquired a dose simply 3-7 days earlier than.

Thus, the research demonstrated that the fourth BNT162b2 vaccine dose continues to be in a position to present safety in opposition to confirmed an infection and extreme sickness with Omicron in comparison with three vaccine doses that got not less than 4 months beforehand.

The safety conferred by the fourth dose is noticed to extend as much as 2-3 weeks, past which additional analysis research are required.

In a further evaluation, the researchers noticed related outcomes for defense in opposition to confirmed infections in chosen teams of people that have been 20-59 years previous.


Whereas the fast-spreading Omicron could evade the immune response induced by three doses of COVID-19 vaccines, the fourth dose of the BNT162b2 vaccine is efficient in opposition to SARS-CoV-2 infections and extreme sickness as a result of COVID-19, as noticed on this research in Israel.

Due to this fact, the Omicron variant, although genetically divergent from the ancestral SARS-CoV-2 pressure in opposition to which the BNT162b2 vaccine was developed, seems inclined to a fourth vaccine dose.

*Necessary discover

medRxiv publishes preliminary scientific experiences that aren’t peer-reviewed and, due to this fact, shouldn’t be thought to be conclusive, information medical observe/health-related habits, or handled as established info




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