Prospective Monitoring of BNT162b2 Second Vaccination Booster Effects in Health Care Workers (HCW)

Prospective Monitoring of BNT162b2 Second Vaccination Booster for Prevention of the COVID-19 Infection in Health Care Workers (HCW)

The SARS-CoV-2 virus causes severe respiratory illness and is an ongoing global pandemic. On December 12, 2020 the FDA approved Pfizer's BioNTech vaccine BNT162b2 which is a messenger RNA type of vaccine for use. This vaccine has shown in numerous studies the ability to induce a strong immune response and provide both humeral and cellular protection against wild type, alpha and delta variants of SARS-CoV2 virus.

In Israel the national vaccine operation began in mid-December 2020 which included 2 initial doses three weeks apart. In August 2021 a first booster (3rd dose) was provided to enhance protection and due to reports of reduced immune response and clinical protection. Several studies have demonstrated that over time there is a decay in the antibody levels, and with them reduced protection.

Recently a new variant of concern has been identified (Omicron) and is causing a surge of infections worldwide. There is lack of knowledge regarding the effectiveness of the current schedule of vaccine against this new variant and whether a second booster (4th dose) will provide higher levels of clinical protection against this variant, currently the ministry of health is considering recommendations for a fourth dose for HCW.

The purpose of this study is to examine whether a fourth dose of vaccination will provide better protection against infection and clinical disease.

Inclusion Criteria:

1. Able to provide written informed consent.
2. Healthcare worker in one of the Clalit Health Services Medical centers and is at least 18 years of age.
3. Completed three doses of BNT162b2 according to MOH guidelines.
4. Third dose was given at least 4 months prior to enrollment.

Exclusion Criteria:

1. History of COVID-19 infection.
2. History of being treated or is currently being treated for any type of Malignancies or other co-morbid conditions that may result in protocol non-compliance.
3. Currently or in the past three months was treated with any type of Immune suppression medication (including chemotherapy, immunomodulatory drugs, biological agents that affect the immune system, any immunosuppressive drug such as corticosteroids).
4. Received in the past 4 months monoclonal antibodies of any type.