There are few data on the immunogenicity of the Pfizer-Biontec BNT162b2 vaccine for the prevention of COVID-19 disease and of side effects in children aged 5-11 years. Therefore, our aim is to determine the immunogenicity and to describe the local or systemic reactogenicity events after vaccination with the BNT162b2 COVID-19 vaccine in children aged 5-11 years for a period of six and half months following the first dose of the vaccine.

The Pfizer-Biontec BNT162b2 vaccine has proven efficacy and safety for the prevention of COVID-19 disease in adults and adolescents aged 12 years and older. Efficacy and safety were recently shown also for children aged 5-11 years. Side-effects are common, including some rare but important side-effects such as myocarditis. Myocarditis post Pfizer-Biontec BNT162b2 vaccination was described mostly among male adolescents and young adults. There are few data on the immunogenicity of the vaccine and of side effects in children aged 5-11 years. Therefore, our aim is to determine the immunogenicity and to describe the local or systemic reactogenicity events after vaccination with the BNT162b2 COVID-19 vaccine in children aged 5-11 years.

This is a prospective cohort study assessing the immunogenicity of the BNT162b2 COVID-19 vaccine in children. The study population will be composed of children aged 5-11 years at the Schneider Children's Medical Center, with no contraindication for COVID-19 vaccination. Upon enrollment in the study, participates will be requested to complete an enrollment questionnaire and a blood sample for baseline serological evaluation will be obtained.

The study follow-up period will be 6 and a half months from receipt of the first dose of the vaccine. The study will last 6 months from the date of the approval of the study protocol.

Blood samples for immune response evaluation will be taken at intervals of 28 days (+/- 14) until 6 and a half months from receipt of the first dose of the vaccine. Samples will be tested for antibodies to SARS-CoV-2 at the Microbiology Laboratory at the Rabin Medical Center. Symptomatic participants with any respiratory symptoms or other symptoms suggestive of COVID-19 disease will be tested for SARS-CoV-2 by RT-PCR, at laboratories certified by the Ministry of Health.

Inclusion Criteria:

Age 5-11 years

Exclusion Criteria:

Administration of COVID-19 vaccine>21 days prior to enrollment, Contraindication for COVID-19 vaccine such as, known hypersensitivity to a component of the vaccine or its excipients Congenital or acquired immunodeficiency (including recipient of systemic steroids ≥2 mg/kg or ≥20mg/day, within two weeks prior to enrollment)

Children aged 5-11 years eligible for BNT162b2 vaccine