**3. Covid-19 vaccines in children**

BNT162b2 (Pfizer; BioNTech) is the first vaccine approved in children (12- 15 years) with 100% efficacy. A trial of this vaccine for six months to eleven years of age is ongoing. Moderna's mRNA-1273 vaccine also has 100% efficacy in adolescents (12-17 years aged). Sinovac's mRNA vaccine is approved in China for children more than three years of age. Protection may be lower against some variants. However, BNT162b2 and AZD122 vaccines have excellent results in reducing hospitalization and severe disease. Phase III trials for beta variants include BNT162b2s01 (Pfizer; BioNTech), Moderna's mRNA-1273.351, and mRNA-1273.211 vaccines [46]. More recent studies revealed that the third dose of vaccine is warranted for active use of

chemotherapy for cancer, hematologic malignancies, hematopoietic stem cell transplantation. Administration of some drugs (rituximab etc.) should be postponed until two-four weeks after vaccination completion if possible [47, 48]. FDA has recently approved BNT162b2 (Pfizer; BioNTech) for individuals aged 16 years and older. It is still under emergency use for children between 12-15 years of age [49].
