A Phase 2 Study to Learn About a Monovalent Pneumococcal Conjugate Candidate in Healthy Toddlers

An AE was any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. Results excluded local reactions and systemic events data.

Time frame: From Dose 1 through 1 month after Dose 2 [up to approximately 3.7 months]

Population: Safety analysis set included all participants who received at least 1 dose of the study intervention. Here, ''Overall Number of Participants Analyzed'' signifies participants who received Dose 1 and who were evaluable for this outcome measure.

Local reactions included redness, swelling and pain at injection site. Redness and swelling were graded as mild: \> 0 to 2.0 centimeter (cm), moderate: \>2.0 to 7.0 cm, severe: \>7.0 cm and Grade 4: necrosis or exfoliative dermatitis (redness) and necrosis (swelling). Pain at injection site was graded as mild: hurt if gently touched, moderate: hurt if gently touched, with crying, severe: caused limitation of limb movement and Grade 4 (potentially life threatening): emergency room visit or hospitalization for severe pain at injection site. Grade 4 assessments were made by the investigator. Any local reaction: any mild, moderate, severe, or Grade 4 redness, swelling, or pain at the injection site.

Time frame: Day 1 through Day 7, where Day 1 is the day of Dose 1 administration (Visit 1 of study)

Population: Safety analysis set included all participants who received at least 1 dose of the study intervention. Here, ''Overall Number of Participants Analyzed'' signifies participants who received Dose 1 and who were evaluable for this outcome measure.

Local reactions included redness, swelling and pain at injection site. Redness and swelling were graded as mild: \> 0 to 2.0 cm, moderate: \>2.0 to 7.0 cm, severe: \>7.0 cm and Grade 4: necrosis or exfoliative dermatitis (redness) and necrosis (swelling). Pain at injection site was graded as mild: hurt if gently touched, moderate: hurt if gently touched, with crying, severe: caused limitation of limb movement and Grade 4 (potentially life threatening): emergency room visit or hospitalization for severe pain at injection site. Grade 4 assessments were made by the investigator. Any local reaction: any mild, moderate, severe, or Grade 4 redness, swelling, or pain at the injection site.

Time frame: Day 1 through Day 7, where Day 1 is the day of Dose 2 administration (Visit 3 of study)

Population: Safety analysis set included all participants who received at least 1 dose of the study intervention. Here, ''Overall Number of Participants Analyzed'' signifies participants who received Dose 2 and who were evaluable for this outcome measure.

An AE was any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was an AE that resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent disability/incapacity; constituted a congenital anomaly/birth defect; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or nonpathogenic; other situations as judged by investigator.

Time frame: From Dose 1 through 1 month after Dose 2 [up to approximately 3.7 months]

Population: Safety analysis set included all participants who received at least 1 dose of the study intervention. Here, ''Overall Number of Participants Analyzed'' signifies participants who received Dose 1 and who were evaluable for this outcome measure.

Fever (oral temperature \>= 38 degree Celsius \[degC\]) was categorized as \>=38.0-38.4 degC, \>38.4-38.9 degC, \>38.9-40.0 degC and \>40.0 degC. Decreased appetite was graded as mild: decreased interest in eating, moderate: decreased oral intake, severe: refusal to feed. Drowsiness was graded as mild: increased/prolonged sleeping bouts, moderate: slightly subdued, interfered daily activity, severe: disabled, not interested in daily activity. Irritability was graded as mild: easily consolable, moderate: required increased attention, severe: inconsolable, crying couldn't be comforted. Grade 4 decreased appetite, drowsiness and irritability events led to emergency room visit or hospitalization and were classified by investigator/medically qualified person. Any systemic event: any fever, decreased appetite, drowsiness, irritability.

Time frame: Day 1 through Day 7, where Day 1 is the day of Dose 1 administration (Visit 1 of study)

Population: Safety analysis set included all participants who received at least 1 dose of the study intervention. Here, ''Overall Number of Participants Analyzed'' signifies participants who received Dose 1 and who were evaluable for this outcome measure.

Fever (oral temperature \>= 38 degC) was categorized as \>=38.0-38.4 degC, \>38.4-38.9 degC, \>38.9-40.0 degC and \>40.0 degC. Decreased appetite was graded as mild: decreased interest in eating, moderate: decreased oral intake, severe: refusal to feed. Drowsiness was graded as mild: increased/prolonged sleeping bouts, moderate: slightly subdued, interfered daily activity, severe: disabled, not interested in daily activity. Irritability was graded as mild: easily consolable, moderate: required increased attention, severe: inconsolable, crying couldn't be comforted. Grade 4 decreased appetite, drowsiness and irritability events led to emergency room visit or hospitalization and were classified by investigator/medically qualified person. Any systemic event: any fever, decreased appetite, drowsiness, irritability.

Time frame: Day 1 through Day 7, where Day 1 is the day of Dose 2 administration (Visit 3 of study)

Population: Safety analysis set included all participants who received at least 1 dose of the study intervention. Here, ''Overall Number of Participants Analyzed'' signifies participants who received Dose 2 and who were evaluable for this outcome measure.

GMCs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the concentrations and the corresponding CIs (based on the student t distribution).

Time frame: 1 month after Dose 1

Population: Dose 1 evaluable immunogenicity population included all participants who were eligible and randomized, received the study intervention to which they were randomized, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 1, and had no other major protocol deviations as determined by the clinician up to the 1-month post-Dose 1 visit.

GMFRs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of fold rises and the corresponding CIs (based on the student-t distribution).

Time frame: From before Dose 1 to 1 month after Dose 1

Population: Dose 1 evaluable immunogenicity population included all participants who were eligible and randomized, received study intervention to which they were randomized, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 1, and had no other major protocol deviations as determined by clinician up to 1-month post-Dose 1 visit. Here, ''Overall Number of Participants Analyzed'' signifies Dose 1 evaluable participants with valid result at both timepoints.

GMTs and the corresponding 2-sided CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on student's t distribution).

Time frame: 1 month after Dose 1

Population: Dose 1 evaluable immunogenicity population included all participants who were eligible and randomized, received study intervention to which they were randomized, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 1, and had no other major protocol deviations as determined by clinician up to 1-month post-Dose 1 visit. Here, ''Overall Number of Participants Analyzed'' signifies Dose 1 evaluable participants with valid OPA titers.

GMCs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the concentrations and the corresponding CIs (based on the student t distribution).

Time frame: 1 month after Dose 2

Population: Dose 2 evaluable immunogenicity population included all participants who were eligible and randomized, received both doses of study intervention to which they were randomly assigned, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 2, and had no other major protocol deviations as determined by the clinician up to the 1-month post-Dose 2 visit.

GMFRs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of fold rises and the corresponding CIs (based on the student-t distribution).

Time frame: From 1 month after Dose 1 to 1 month after Dose 2

Population: Dose 2 evaluable immunogenicity population included all participants who were eligible, randomized, received both doses of study intervention to which they were randomly assigned, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 2, had no major protocol deviations as determined by clinician up to 1-month post-Dose 2 visit. Here, ''Overall Number of Participants Analyzed'' signifies Dose 2 evaluable participants with valid result at both timepoints.

GMFRs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of fold rises and the corresponding CIs (based on the student-t distribution).

Time frame: From 1 month after Dose 1 to 1 month after Dose 2

Population: Dose 2 evaluable immunogenicity population included all participants who were eligible, randomized, received both doses of study intervention to which they were randomly assigned, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 2, had no major protocol deviations as determined by clinician up to 1-month post-Dose 2 visit. Here, ''Overall Number of Participants Analyzed'' signifies Dose 2 evaluable participants with valid OPA result at both timepoints.

GMFRs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of fold rises and the corresponding CIs (based on the student-t distribution).

Time frame: From before Dose 1 to 1 month after Dose 1

Population: Dose 1 evaluable immunogenicity population included all participants who were eligible and randomized, received study intervention to which they were randomized, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 1, and had no other major protocol deviations as determined by clinician up to 1-month post-Dose 1 visit. Here, ''Overall Number of Participants Analyzed'' signifies Dose 1 evaluable participants with valid OPA result at both timepoints.

GMTs and the corresponding 2-sided CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on student's t distribution).

Time frame: 1 month after Dose 2

Population: Dose 2 evaluable immunogenicity population included all participants who were eligible, randomized, received both doses of study intervention to which they were randomly assigned, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 2, had no major protocol deviations as determined by clinician up to 1-month post-Dose 2 visit. Here, ''Overall Number of Participants Analyzed'' signifies Dose 2 evaluable participants with valid OPA titers.

Predefined IgG concentrations was \>= 0.35 micrograms per milliliter (mcg/mL).

Time frame: 1 month after Dose 1

Population: Dose 1 evaluable immunogenicity population included all participants who were eligible and randomized, received the study intervention to which they were randomized, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 1, and had no other major protocol deviations as determined by the clinician up to the 1-month post-Dose 1 visit.

Predefined level of IgG concentrations was \>= 0.35 mcg/mL.

Time frame: 1 month after Dose 2

Population: Dose 2 evaluable immunogenicity population included all participants who were eligible and randomized, received both doses of study intervention to which they were randomly assigned, had at least 1 valid immunogenicity result within 27 to 56 days, inclusive, after Dose 2, and had no other major protocol deviations as determined by the clinician up to the 1-month post-Dose 2 visit.