Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an electronic diary (e-diary). Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 centimeter (cm). Redness and swelling were graded as mild (greater than \[\>\] 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain).

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain).

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 hours\[h\]), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization).

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization).

An AE was any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. For BNT162b1 100 mcg, participants received one dose of 100 mcg, followed by one dose of 10 mcg.

An SAE was any untoward medical occurrence that occurred, at any dose: resulted in death; required inpatient hospitalization or prolongation of existing hospitalization; was life-threatening; resulted in persistent or significant disability/ incapacity; was a congenital anomaly/birth defect and other important medical events. For BNT162b1 100 mcg, participants received one dose of 100 mcg, followed by one dose of 10 mcg.

Hematology parameters that were assessed included hemoglobin, hematocrit, erythrocytes, Ery. mean corpuscular volume, Ery. mean corpuscular hemoglobin, Ery. mean corpuscular HGB concentration, platelets, leukocytes, lymphocytes, neutrophils, basophils, eosinophils and monocytes. Abnormal parameters were determined by following criteria: Hemoglobin : \<0.8x lower limit of normal (LLN), Hematocrit : \<0.8x LLN, Erythrocytes : \<0.8x LLN, Ery. Mean Corpuscular Volume: \<0.9x LLN, Ery. Mean Corpuscular Hemoglobin : \<0.9x LLN Ery. Mean Corpuscular HGB Concentration : \<0.9x LLN, Platelets : \<0.5x LLN, Leukocytes : \<0.6x LLN, Lymphocytes : \<0.8x LLN, Neutrophils : \<0.8x LLN, Basophils: \>1.2x upper limit of normal (ULN), Eosinophils \>1.2x ULN, Monocytes \>1.2x ULN. Only parameters with abnormal values were reported in this outcome measure.

Hematology parameters that were assessed included hemoglobin, hematocrit, erythrocytes, Ery. mean corpuscular volume, Ery. mean corpuscular hemoglobin, Ery. mean corpuscular HGB concentration, platelets, leukocytes, lymphocytes, neutrophils, basophils, eosinophils and monocytes. Abnormal parameters were determined by following criteria: Hemoglobin : \<0.8x LLN, Hematocrit : \<0.8x LLN, Erythrocytes : \<0.8x LLN, Ery. Mean Corpuscular Volume: \<0.9x LLN, Ery. Mean Corpuscular Hemoglobin : \<0.9x LLN Ery. Mean Corpuscular HGB Concentration : \<0.9x LLN, Platelets : \<0.5x LLN, Leukocytes : \<0.6x LLN, Lymphocytes : \<0.8x LLN, Neutrophils : \<0.8x LLN, Basophils: \>1.2x ULN, Eosinophils \>1.2x ULN, Monocytes \>1.2x ULN. Only parameters with abnormal values were reported in this outcome measure.

Hematology parameters that were assessed included hemoglobin, hematocrit, erythrocytes, Ery. mean corpuscular volume, Ery. mean corpuscular hemoglobin, Ery. mean corpuscular HGB concentration, platelets, leukocytes, lymphocytes, neutrophils, basophils, eosinophils and monocytes. Abnormal parameters were determined by following criteria: Hemoglobin : \<0.8x LLN, Hematocrit : \<0.8x LLN, Erythrocytes : \<0.8x LLN, Ery. Mean Corpuscular Volume: \<0.9x LLN, Ery. Mean Corpuscular Hemoglobin : \<0.9x LLN Ery. Mean Corpuscular HGB Concentration : \<0.9x LLN, Platelets : \<0.5x LLN, Leukocytes : \<0.6x LLN, Lymphocytes : \<0.8x LLN, Neutrophils : \<0.8x LLN, Basophils: \>1.2x ULN, Eosinophils \>1.2x ULN, Monocytes \>1.2x ULN. Only parameters with abnormal values were reported in this outcome measure.

Hematology parameters that were assessed included hemoglobin, hematocrit, erythrocytes, Ery. mean corpuscular volume, Ery. mean corpuscular hemoglobin, Ery. mean corpuscular HGB concentration, platelets, leukocytes, lymphocytes, neutrophils, basophils, eosinophils and monocytes. Abnormal parameters were determined by following criteria: Hemoglobin : \<0.8x LLN, Hematocrit : \<0.8x LLN, Erythrocytes : \<0.8x LLN, Ery. Mean Corpuscular Volume: \<0.9x LLN, Ery. Mean Corpuscular Hemoglobin : \<0.9x LLN Ery. Mean Corpuscular HGB Concentration : \<0.9x LLN, Platelets : \<0.5x LLN, Leukocytes : \<0.6x LLN, Lymphocytes : \<0.8x LLN, Neutrophils : \<0.8x LLN, Basophils: \>1.2x ULN, Eosinophils \>1.2x ULN, Monocytes \>1.2x ULN. Only parameters with abnormal values were reported in this outcome measure.

Chemistry parameters that were assessed included bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), urea nitrogen, creatinine. Abnormal parameters were determined by following criteria: bilirubin: \>1.5x ULN, AST: \>3.0x ULN, ALT: \>3.0x ULN, ALP: \>3.0x ULN, urea nitrogen: \>1.3x ULN, creatinine: \>1.3x ULN. Abnormal values reported for this outcome measure are for bilirubin.

Chemistry parameters that were assessed included bilirubin, AST, ALT, ALP, urea nitrogen, creatinine. Abnormal parameters were determined by following criteria: bilirubin: \>1.5x ULN, AST: \>3.0x ULN, ALT: \>3.0x ULN, ALP: \>3.0x ULN, urea nitrogen: \>1.3x ULN, creatinine: \>1.3x ULN. Abnormal values reported for this outcome measure are for bilirubin.

Chemistry parameters that were assessed included bilirubin, AST, ALT, ALP, urea nitrogen, creatinine. Abnormal parameters were determined by following criteria: bilirubin: \>1.5x ULN, AST: \>3.0x ULN, ALT: \>3.0x ULN, ALP: \>3.0x ULN, urea nitrogen: \>1.3x ULN, creatinine: \>1.3x ULN. Abnormal values reported for this outcome measure are for bilirubin.

Chemistry parameters that were assessed included bilirubin, AST, ALT, ALP, urea nitrogen, creatinine. Abnormal parameters were determined by following criteria: bilirubin: \>1.5x ULN, AST: \>3.0x ULN, ALT: \>3.0x ULN, ALP: \>3.0x ULN, urea nitrogen: \>1.3x ULN, creatinine: \>1.3x ULN. Abnormal values reported for this outcome measure are for bilirubin.

Percentage of participants with grade shift in hematology parameters reported in this outcome measure. Grade(G)1: Mild, G2:Moderate, G3:Severe, G4:potentially life threatening. Hemoglobin(Female): G1: 11.0 - 12.0grams per deciliter(g/dL), G2: 9.5 - 10.9, G3: 8.0 - 9.4, G4: \<8.0. Hemoglobin(Male): G1: 12.5 - 13.5, G2: 10.5 - 12.4, G3: 8.5 - 10.4, G4: \<8.5. WBC decrease(cells/mm3):G1: 2,500 - 3,500, G2: 1,500 - 2,499, G3: 1,000 - 1,499, G4: \<1,000 Lymphocytes decrease(cells/mm3): G1: 750 - 1,000, G2: 500 - 749, G3: 250 - 499, G4: \<250. Eosinophils(cells/mm3):G1: 650 - 1500, G2: 1501 - 5000, G3: \>5000, G4:Hypereosinophilic. Platelets decreased(cells/mm3): G1: 125,000 - 140,000, G2: 100,000 - 124,000, G3: 25,000 - 99,000, G4: \<25,000. Urea Nitrogen (mg/dl): G1: 23-26; G2:27-31; G3: \>31; G4: requires dialysis. Only parameters where grade shift was observed were reported.

Percentage of participants with grade shift in hematology parameters reported in this outcome measure. Grade(G)1: Mild, G2:Moderate, G3:Severe, G4:potentially life threatening. Hemoglobin(Female): G1: 11.0 - 12.0grams per deciliter(g/dL), G2: 9.5 - 10.9, G3: 8.0 - 9.4, G4: \<8.0. Hemoglobin(Male): G1: 12.5 - 13.5, G2: 10.5 - 12.4, G3: 8.5 - 10.4, G4: \<8.5. WBC decrease(cells/mm3):G1: 2,500 - 3,500, G2: 1,500 - 2,499, G3: 1,000 - 1,499, G4: \<1,000 Lymphocytes decrease(cells/mm3): G1: 750 - 1,000, G2: 500 - 749, G3: 250 - 499, G4: \<250. Eosinophils(cells/mm3):G1: 650 - 1500, G2: 1501 - 5000, G3: \>5000, G4:Hypereosinophilic. Platelets decreased(cells/mm3): G1: 125,000 - 140,000, G2: 100,000 - 124,000, G3: 25,000 - 99,000, G4: \<25,000. Urea Nitrogen (mg/dl): G1: 23-26; G2:27-31; G3: \>31; G4: requires dialysis. Only parameters where grade shift was observed were reported.

Percentage of participants with grade shift in hematology parameters reported in this outcome measure. Grade(G)1: Mild, G2:Moderate, G3:Severe, G4:potentially life threatening. Hemoglobin(Female): G1: 11.0 - 12.0grams per deciliter(g/dL), G2: 9.5 - 10.9, G3: 8.0 - 9.4, G4: \<8.0. Hemoglobin(Male): G1: 12.5 - 13.5, G2: 10.5 - 12.4, G3: 8.5 - 10.4, G4: \<8.5. WBC decrease(cells/mm3):G1: 2,500 - 3,500, G2: 1,500 - 2,499, G3: 1,000 - 1,499, G4: \<1,000 Lymphocytes decrease(cells/mm3): G1: 750 - 1,000, G2: 500 - 749, G3: 250 - 499, G4: \<250. Eosinophils(cells/mm3):G1: 650 - 1500, G2: 1501 - 5000, G3: \>5000, G4:Hypereosinophilic. Platelets decreased(cells/mm3): G1: 125,000 - 140,000, G2: 100,000 - 124,000, G3: 25,000 - 99,000, G4: \<25,000. Urea Nitrogen (mg/dl): G1: 23-26; G2:27-31; G3: \>31; G4: requires dialysis. Only parameters where grade shift was observed were reported.

Percentage of participants with grade shift in hematology parameters reported in this outcome measure. Grade(G)1: Mild, G2:Moderate, G3:Severe, G4:potentially life threatening. Hemoglobin(Female): G1: 11.0 - 12.0grams per deciliter(g/dL), G2: 9.5 - 10.9, G3: 8.0 - 9.4, G4: \<8.0. Hemoglobin(Male): G1: 12.5 - 13.5, G2: 10.5 - 12.4, G3: 8.5 - 10.4, G4: \<8.5. WBC decrease(cells/mm3):G1: 2,500 - 3,500, G2: 1,500 - 2,499, G3: 1,000 - 1,499, G4: \<1,000 Lymphocytes decrease(cells/mm3): G1: 750 - 1,000, G2: 500 - 749, G3: 250 - 499, G4: \<250. Eosinophils(cells/mm3):G1: 650 - 1500, G2: 1501 - 5000, G3: \>5000, G4:Hypereosinophilic. Platelets decreased(cells/mm3): G1: 125,000 - 140,000, G2: 100,000 - 124,000, G3: 25,000 - 99,000, G4: \<25,000. Urea Nitrogen (mg/dl): G1: 23-26; G2:27-31; G3: \>31; G4: requires dialysis. Only parameters where grade shift was observed were reported.

Percentage of participants with grade shift in chemistry were reported in this outcome measure. G1: Mild, G2: Moderate, G3: Severe, G4: potentially life threatening. BUN(milligram per deciliter \[mg/dL\]): G1: 23 - 26, G2: 27 - 31, G3: \>31, G4: required dialysis. Creatinine(mg/dL): G1: 1.5 - 1.7, G2: 1.8 - 2.0, G3: 2.1 - 2.5, G4: \> 2.5 or required dialysis. Alkaline phosphate(increase by factor): G1: 1.1 - 2.0 x ULN G2: 2.1 - 3.0 x ULN G3: 3.1 -10 x ULN, G4: \>10 x ULN. Liver function tests(ALT, AST increase by factor): G1: 1.1 - 2.5 x ULN G2: 2.6 - 5.0 x ULN G3: 5.1 - 10 x ULN, G4: \>10 x ULN. Bilirubin(when accompanied by any increase in liver function test - increase by factor): G1: 1.1 - 1.25 x ULN G2: 1.26 - 1.5 x ULN G3: 1.51 - 1.75 x ULN, G4: \>1.75 x ULN. Bilirubin(when liver function test is normal - increase by factor): G1: 1.1 - 1.5 x ULN, G2: 1.6 - 2.0 x ULN, G3: 2.0 - 3.0 x ULN, G4: \>3.0 x ULN. Only parameters where grade shift was observed were reported.

Percentage of participants with grade shift in chemistry were reported in this outcome measure. G1: Mild, G2: Moderate, G3: Severe, G4: potentially life threatening. BUN(mg/dL): G1: 23 - 26, G2: 27 - 31, G3: \>31, G4: required dialysis. Creatinine(mg/dL): G1: 1.5 - 1.7, G2: 1.8 - 2.0, G3: 2.1 - 2.5, G4: \> 2.5 or required dialysis. Alkaline phosphate(increase by factor): G1: 1.1 - 2.0 x ULN G2: 2.1 - 3.0 x ULN G3: 3.1 -10 x ULN, G4: \>10 x ULN. Liver function tests(ALT, AST increase by factor): G1: 1.1 - 2.5 x ULN G2: 2.6 - 5.0 x ULN G3: 5.1 - 10 x ULN, G4: \>10 x ULN. Bilirubin(when accompanied by any increase in liver function test - increase by factor): G1: 1.1 - 1.25 x ULN G2: 1.26 - 1.5 x ULN G3: 1.51 - 1.75 x ULN, G4: \>1.75 x ULN. Bilirubin(when liver function test is normal - increase by factor): G1: 1.1 - 1.5 x ULN, G2: 1.6 - 2.0 x ULN, G3: 2.0 - 3.0 x ULN, G4: \>3.0 x ULN. Only parameters where grade shift was observed were reported.

Percentage of participants with grade shift in chemistry were reported in this outcome measure. G1: Mild, G2: Moderate, G3: Severe, G4: potentially life threatening. BUN(mg/dL): G1: 23 - 26, G2: 27 - 31, G3: \>31, G4: required dialysis. Creatinine(mg/dL): G1: 1.5 - 1.7, G2: 1.8 - 2.0, G3: 2.1 - 2.5, G4: \> 2.5 or required dialysis. Alkaline phosphate(increase by factor): G1: 1.1 - 2.0 x ULN G2: 2.1 - 3.0 x ULN G3: 3.1 -10 x ULN, G4: \>10 x ULN. Liver function tests(ALT, AST increase by factor): G1: 1.1 - 2.5 x ULN G2: 2.6 - 5.0 x ULN G3: 5.1 - 10 x ULN, G4: \>10 x ULN. Bilirubin(when accompanied by any increase in liver function test - increase by factor): G1: 1.1 - 1.25 x ULN G2: 1.26 - 1.5 x ULN G3: 1.51 - 1.75 x ULN, G4: \>1.75 x ULN. Bilirubin(when liver function test is normal - increase by factor): G1: 1.1 - 1.5 x ULN, G2: 1.6 - 2.0 x ULN, G3: 2.0 - 3.0 x ULN, G4: \>3.0 x ULN. Only parameters where grade shift was observed were reported.

Percentage of participants with grade shift in chemistry were reported in this outcome measure. G1: Mild, G2: Moderate, G3: Severe, G4: potentially life threatening. BUN(mg/dL): G1: 23 - 26, G2: 27 - 31, G3: \>31, G4: required dialysis. Creatinine(mg/dL): G1: 1.5 - 1.7, G2: 1.8 - 2.0, G3: 2.1 - 2.5, G4: \> 2.5 or required dialysis. Alkaline phosphate(increase by factor): G1: 1.1 - 2.0 x ULN G2: 2.1 - 3.0 x ULN G3: 3.1 -10 x ULN, G4: \>10 x ULN. Liver function tests(ALT, AST increase by factor): G1: 1.1 - 2.5 x ULN G2: 2.6 - 5.0 x ULN G3: 5.1 - 10 x ULN, G4: \>10 x ULN. Bilirubin(when accompanied by any increase in liver function test - increase by factor): G1: 1.1 - 1.25 x ULN G2: 1.26 - 1.5 x ULN G3: 1.51 - 1.75 x ULN, G4: \>1.75 x ULN. Bilirubin(when liver function test is normal - increase by factor): G1: 1.1 - 1.5 x ULN, G2: 1.6 - 2.0 x ULN, G3: 2.0 - 3.0 x ULN, G4: \>3.0 x ULN. Only parameters where grade shift was observed were reported.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants or parents/legal guardians in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain).

Local reactions included redness, swelling and, pain at the injection site, recorded by participants or parents/legal guardians in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain).

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization).

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization).

An AE was any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. HIV positive participants were excluded from this analysis.

An SAE was any untoward medical occurrence that occurred, at any dose: resulted in death; required inpatient hospitalization or prolongation of existing hospitalization; was life-threatening; resulted in persistent or significant disability/ incapacity; was a congenital anomaly/birth defect and other important medical events. HIV positive participants were excluded from this analysis.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain).

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain).

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization).

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization).

An AE was any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment.

A SAE was any untoward medical occurrence that occurred, at any dose: resulted in death; required inpatient hospitalization or prolongation of existing hospitalization; was life-threatening; resulted in persistent or significant disability/ incapacity; was a congenital anomaly/birth defect and other important medical events.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants or parents/legal guardians in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain). HIV positive participants were excluded.

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization). HIV positive participants were excluded.

An AE was any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. HIV positive participants were excluded.

A SAE was any untoward medical occurrence that occurred, at any dose: resulted in death; required inpatient hospitalization or prolongation of existing hospitalization; was life-threatening; resulted in persistent or significant disability/ incapacity; was a congenital anomaly/birth defect and other important medical events. HIV positive participants were excluded.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain). HIV positive participants were excluded from this analysis.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain). HIV positive participants were excluded from this analysis.

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization). HIV positive participants excluded.

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization). HIV positive participants excluded.

An AE was any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. HIV positive participants were excluded.

An SAE was any untoward medical occurrence that occurred, at any dose: resulted in death; required inpatient hospitalization or prolongation of existing hospitalization; was life-threatening; resulted in persistent or significant disability/ incapacity; was a congenital anomaly/birth defect and other important medical events. HIV positive participants were excluded.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain). HIV positive participants were excluded.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain). HIV positive participants were excluded.

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization). HIV positive participants were excluded.

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization). HIV positive participants were excluded.

An AE was any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. HIV positive participants were excluded.

A SAE was any untoward medical occurrence that occurred, at any dose: resulted in death; required inpatient hospitalization or prolongation of existing hospitalization; was life-threatening; resulted in persistent or significant disability/ incapacity; was a congenital anomaly/birth defect and other important medical events. HIV positive participants were excluded.

Local reactions included redness, swelling and, pain at the injection site, recorded by participants in an e-diary. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit =0.5 cm. Redness and swelling were graded as mild (\> 2.0 to 5.0 cm), moderate (\> 5.0 to 10.0 cm), severe (\>10.0 cm) and Grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (does not interfere with activity), moderate (interferes with activity), severe (prevents daily activity) and Grade 4 (emergency room visit or hospitalization for severe pain). HIV positive participants were excluded.

Systemic events included fever, fatigue, headache, chills, vomiting, diarrhea, new or worsened muscle pain, new or worsened joint pain recorded by participants or parents/legal guardians of participants using e-diary. Fever=temperature \>=38.0 deg C categorized as \>=38.0 to 38.4, \>38.4 to 38.9, \>38.9 to 40.0 and \>40.0 deg C. Fatigue, headache, chills, new or worsened muscle pain, new or worsened joint pain graded as mild (does not interfere with activity), moderate (some interference with activity), severe (prevents daily routine activity), Grade 4 (Emergency room visit/hospitalization). Vomiting: mild (1-2 times in 24 h), moderate (\>2 times in 24 h), severe (requires IV hydration), Grade 4 (emergency room visit/hospitalization for hypotensive shock). Diarrhea: mild (2-3 loose stools in 24h), moderate (4-5 loose stools in 24 h), severe (\>=6 loose stools in 24 h) and Grade 4 (emergency room visit/hospitalization). HIV positive participants were excluded.

An AE was any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. HIV positive participants were excluded.

A SAE was any untoward medical occurrence that occurred, at any dose: resulted in death; required inpatient hospitalization or prolongation of existing hospitalization; was life-threatening; resulted in persistent or significant disability/ incapacity; was a congenital anomaly/birth defect and other important medical events. HIV positive participants were excluded.

Occurrences of first COVID-19 infection in participants followed up based on central laboratory or locally confirmed NAAT in participants, without serological or virological evidence of prior SARS-CoV-2 infection were reported in this outcome measure. HIV positive participants were excluded from this analysis.

Occurrences of first COVID-19 infection in participants followed up based on central laboratory or locally confirmed NAAT in participants, without serological or virological evidence of prior SARS-CoV-2 infection (analysis for EUA) were reported in this outcome measure.

Occurrences of first COVID-19 infection in participants followed up based on central laboratory or locally confirmed NAAT in participants, with or without serological or virological evidence of prior SARS-CoV-2 infection were reported in this outcome measure.

Occurrences of first COVID-19 infection in participants followed up based on central laboratory or locally confirmed NAAT in participants, with or without serological or virological evidence (analysis for EUA) of prior SARS-CoV-2 infection were reported in this outcome measure. HIV positive participants were excluded from this analysis.

GMR based on geometric mean titer, comparison of 1 month after dose 2 between vaccine groups: BNT162b2-naive participants without evidence of infection up to 1 month after dose 2 were reported in this outcome measure. HIV positive participants excluded from this analysis.

Seroresponse was defined as achieving a \>=4-fold rise from baseline (before Dose 1). If the baseline measurement was below the lower limit of quantification (LLOQ), a post vaccination assay result \>=4 × LLOQ was considered a seroresponse. HIV positive participants excluded.

GMR based on geometric mean titer, comparison of 1 month after booster dose to 1 month after dose 2 for BNT162b2-experienced participants were reported in this outcome measure. HIV positive participants excluded from this analysis.

Percentage difference of participants achieving seroresponse - comparison of 1 month after booster dose to 1 month after Dose 2 BNT162b2-experienced participants without evidence of infection up to 1 month after booster dose who were rerandomized to receive 1 booster dose were reported in this outcome measure. Seroresponse was defined as achieving a \>=4-fold rise from baseline (before Dose 1). If the baseline measurement was below the LLOQ, a postvaccination assay result \>=4 × LLOQ was considered a seroresponse. HIV positive participants excluded.

GMR of neutralizing titers (E2a) for comparison of 1 month after booster dose to 1 month after dose 2: BNT162b2-experienced participants in Phase 3 were reported in this outcome measure. HIV positive participants were excluded from this analysis.

Percentage difference of participants achieving seroresponse - comparison of 1 month after booster dose to 1 month after Dose 2 BNT162b2-experienced participants without evidence of infection up to 1 month after booster dose who were rerandomized to receive 1 booster dose were reported in this outcome measure. Seroresponse was defined as achieving a \>=4-fold rise from baseline (before Dose 1). If the baseline measurement was below the LLOQ, a postvaccination assay result \>=4 × LLOQ was considered a seroresponse. HIV positive participants excluded.