* age \<18 years * positive test for specific antibodies igg and igm antibodies result for sars cov-2 * primary or secondary immunosuppression * use of immunosuppression drugs, use of hydroxychloroquine, cloroquine, azithromycin, lopinavir/ritonavir, ivermectin or any other drug used to treat patients covid-19 before the enrollment. * chemotherapy treatment * presence of antibodies iga, igm, igg against sars-cov-2 * pregnancy or breastfeeding * missing informed consent form * fever \> 38° in the previous 24 hours * any bcg vaccine contraindication * history of previous allergy to the components of the vaccine * already part of any other trial * previous or active tuberculosis (tb) disease * another vaccine administrated 4 months before the start of the trial. * any underlying history of malignancy or lymphoma. * actual treatment with steroids * absence of more than 1 month from the hospital, from the study period.

* age \<18 years * positive test for specific antibodies igg and igm antibodies result for sars cov-2 * primary or secondary immunosuppression * use of immunosuppression drugs, use of hydroxychloroquine, cloroquine, azithromycin, lopinavir/ritonavir, ivermectin or any other drug used to treat patients covid-19 before the enrollment. * chemotherapy treatment * presence of antibodies iga, igm, igg against sars-cov-2 * pregnancy or breastfeeding * missing informed consent form * fever \> 38° in the previous 24 hours * any bcg vaccine contraindication * history of previous allergy to the components of the vaccine * already part of any other trial * previous or active tuberculosis (tb) disease * another vaccine administrated 4 months before the start of the trial. * any underlying history of malignancy or lymphoma. * actual treatment with steroids * absence of more than 1 month from the hospital, from the study period.

- age <18 years - positive test for specific antibodies igg and igm antibodies result for sars cov-2 - primary or secondary immunosuppression - use of immunosuppression drugs, use of hydroxychloroquine, cloroquine, azithromycin, lopinavir/ritonavir, ivermectin or any other drug used to treat patients covid-19 before the enrollment. - chemotherapy treatment - presence of antibodies iga, igm, igg against sars-cov-2 - pregnancy or breastfeeding - missing informed consent form - fever > 38° in the previous 24 hours - any bcg vaccine contraindication - history of previous allergy to the components of the vaccine - already part of any other trial - previous or active tuberculosis (tb) disease - another vaccine administrated 4 months before the start of the trial. - any underlying history of malignancy or lymphoma. - actual treatment with steroids - absence of more than 1 month from the hospital, from the study period.

- age <18 years - positive test for specific antibodies igg and igm antibodies result for sars cov-2 - primary or secondary immunosuppression - use of immunosuppression drugs, use of hydroxychloroquine, cloroquine, azithromycin, lopinavir/ritonavir, ivermectin or any other drug used to treat patients covid-19 before the enrollment. - chemotherapy treatment - presence of antibodies iga, igm, igg against sars-cov-2 - pregnancy or breastfeeding - missing informed consent form - fever > 38° in the previous 24 hours - any bcg vaccine contraindication - history of previous allergy to the components of the vaccine - already part of any other trial - previous or active tuberculosis (tb) disease - another vaccine administrated 4 months before the start of the trial. - any underlying history of malignancy or lymphoma. - actual treatment with steroids - absence of more than 1 month from the hospital, from the study period.