The solicited administration site events include tenderness, erythema, induration and swelling.

The solicited systemic events include fever, irritability/fussiness, loss of appetite, drowsiness, vomiting and diarrhoea. Fever is defined as temperature \>38.0°C/100.4°F. The preferred location for measuring temperature will be axillary.

Unsolicited AEs includes any AE reported in addition to those solicited during the clinical study. Also, any 'solicited' symptom with onset outside the specified period of follow-up for solicited symptoms is reported as an unsolicited adverse event. MAEs are defined as symptoms or illnesses requiring a hospitalization, or an emergency room visit, or visit to/by a health care provider. An SAE is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization or results in disability/incapacity. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation in order to characterize and understand it.

MAEs are defined as symptoms or illnesses requiring a hospitalization, or an emergency room visit, or visit to/by a health care provider. An SAE is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization or results in disability/incapacity. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation in order to characterize and understand it.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenB vaccine is evaluated by measuring bactericidal activity using an hSBA against all serogroup B indicator strains.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenB vaccine is evaluated by measuring bactericidal activity using an hSBA against all serogroup B indicator strains.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenB vaccine against serogroup B indicator strains is determined using hSBA GMTs. For each serogroup B indicator strain 90% CIs for the GMTs ratio between ABCWY-2Gen low dose/ ABCWY-2Gen high dose and MenB, is created by exponentiating (base 10) the least squares means and the lower and upper limits of the 90% CIs of the log transformed titers (base 10) obtained from a 2-way Analysis of Variance (ANOVA) with factors for arms and center.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenB vaccine against serogroup B indicator strains is determined using hSBA GMTs. For each serogroup B indicator strain 90% CIs for the GMTs ratio between ABCWY-2Gen low dose/ ABCWY-2Gen high dose and MenB, is created by exponentiating (base 10) the least squares means and the lower and upper limits of the 90% CIs of the log transformed titers (base 10) obtained from a 2-way ANOVA with factors for arms and center.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenB vaccine against serogroup B indicator strains is determined using hSBA GMRs. Within-group ratios of hSBA GMTs against each of the N.meningitidis serogroup B indicator strain at Day 331 compared to Day 301.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenACWY-TT vaccine is evaluated by measuring bactericidal activity using an hSBA against serogroups A, C, W and Y. The percentages of participants with hSBA titers ≥ LLOQ and the corresponding exact 2-sided 95% CIs based on Clopper-Pearson method are calculated.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenACWY-TT vaccine against serogroups A, C, W and Y is determined using hSBA GMTs. For each A, C, W, and Y serogroup 90% CIs for the GMTs ratio between ABCWY-2Gen low dose/ ABCWY-2Gen high dose and MenACWY-TT, is created by exponentiating (base 10) the least squares means and the lower and upper limits of the 90% CIs of the log transformed titers (base 10) obtained from a 2-way ANOVA with factors for arms and center.

The immune response to the MenABCWY-2Gen vaccine (low and high dose), the MenABCWY-1Gen vaccine and the MenACWY-TT vaccine against serogroups A, C, W and Y is determined using hSBA GMRs. Within-group ratios of hSBA GMTs against each of the N.meningitidis A, C, W and Y serogroups at Day 331 compared to Day 301.

The solicited administration site events include injection site pain, erythema (redness), swelling and induration. Any solicited administration site AEs = occurrence of the symptom regardless of intensity grade.

The solicited systemic events include fever (temperature ≥ 38.0°C), nausea, fatigue, myalgia, arthralgia and headache.

Unsolicited AEs includes any AE reported in addition to those solicited during the clinical study. Also, any 'solicited' symptom with onset outside the specified period of follow-up for solicited symptoms is reported as an unsolicited adverse event. A SAE is any untoward medical occurrence that results in death, is life-threatening, requires or prolongs hospitalization, results in disability/incapacity and is a congenital anomaly/birth defect in a subject's offspring. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation to characterize and understand it. A participant was considered withdrawn if no study procedures occurred, and no follow-up or further information has been collected from the date of withdrawal or last contact.

Unsolicited AEs includes any AE reported in addition to those solicited during the clinical study. Also, any 'solicited' symptom with onset outside the specified period of follow-up for solicited symptoms is reported as an unsolicited adverse event. A SAE is any untoward medical occurrence that results in death, is life-threatening, requires or prolongs hospitalization, results in disability/incapacity and is a congenital anomaly/birth defect in a subject's offspring. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation to characterize and understand it. A participant was considered withdrawn if no study procedures occurred, and no follow-up or further information has been collected from the date of withdrawal or last contact.

A SAEs is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity and is a congenital anomaly/birth defect in the offspring of a study subject. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation to characterize and understand it. A participant was considered withdrawn if no study procedures occurred, and no follow-up or further information has been collected from the date of withdrawal or last contact.

The safety laboratory data included haematological parameters (basophils, eosinophils, Erythrocytes, hemoglobin, leukocytes, lymphocytes, monocytes, platelets and neutrophils), and chemical parameters (Alanine Aminotransferase \[ALT\], Aspartate Aminotransferase \[AST\], Creatinine) Below = value below the laboratory reference range defined for the specified visit and laboratory parameter; Within = value within the laboratory reference range defined for the specified visit and laboratory parameter; Above = value above the laboratory reference range defined for the specified visit and laboratory parameter.

Clinical laboratory testing included hematological and biochemical laboratory values. Any abnormal laboratory test result (e.g., in hematology or clinical chemistry) that was deemed clinically significant by the investigator's medical and scientific judgment, and not related to an underlying disease, was reported as an unsolicited adverse event (AE) unless it was considered by the investigator to be more severe than expected for the participant's condition. The safety laboratory data included hematological parameters (basophils, eosinophils, erythrocytes, hemoglobin, leukocytes, lymphocytes, monocytes, platelets, and neutrophils) and chemical parameters (Alanine Aminotransferase \[ALT\], Aspartate Aminotransferase \[AST\], and creatinine).

The effectiveness of the MenABCWY-2Gen (low \& high dose) vaccine when administered at 0,2- or 0,6-months schedule compared to MenB vaccine administered at 0,6-months schedule, against a panel of 110 randomly selected endemic N. meningitidis serogroup B strains is measured in terms of percentage of samples with bactericidal activity using endogenous complement human Serum Bactericidal Assay (enc-hSBA), which provides a qualitative assessment (yes/no) of the presence of sufficient bactericidal antibodies in human sera to kill a meningococcal strain at a specific dilution of 1:4.

The immune response to the MenABCWY-2Gen (low and high dose) vaccine when administered at 0,2- or 0,6-months schedule compared to MenACWY vaccine (single dose), relative to day 1 in the ABCWY and control groups (0, 6 month schedule) and day 31 in ABCWY (0, 2 month schedule) is measured in terms of number of participants achieving a 4-fold rise in hSBA titers against serogroups A, C, W and Y. The 4-fold rise is defined as: -a post-vaccination hSBA titer ≥ 16 for participants with a pre-vaccination hSBA titer \< 4, -a post-vaccination hSBA titer ≥ 4 times the lower limit of quantitation (LLOQ) for participants with a pre-vaccination hSBA titer ≥LOD but \<LLOQ, and. -a post-vaccination hSBA titer ≥ 4 times the pre-vaccination hSBA titer for participants with a pre-vaccination hSBA titer ≥LLOQ.

Assessed solicited administration site events included injection site pain, erythema (redness), swelling and induration. Any = occurrence of the event regardless of intensity grade.

Assessed solicited systemic events included fever (temperature ≥ 38.0°C), nausea, fatigue, myalgia, arthralgia and headache. Any = occurrence of the event regardless of intensity grade or relation to the study vaccination.

Unsolicited AEs includes any AE reported in addition to those solicited during the clinical study. Also, any 'solicited' symptom with onset outside the specified period of follow-up for solicited symptoms is reported as an unsolicited adverse event. A SAE is any untoward medical occurrence that results in death, is life-threatening, requires or prolongs hospitalization, results in disability/incapacity and is a congenital anomaly/birth defect in a subject's offspring. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation to characterize and understand it. A participant was considered withdrawn if no study procedures occurred, and no follow-up or further information has been collected from the date of withdrawal or last contact.

A SAEs is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity and is a congenital anomaly/birth defect in the offspring of a study subject. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation to characterize and understand it. A participant was considered withdrawn if no study procedures occurred, and no follow-up or further information has been collected from the date of withdrawal or last contact.

Assessed solicited administration site events included injection site pain, erythema (redness), swelling and induration. Any = occurrence of the event regardless of intensity grade.

Assessed solicited systemic events included fever (temperature ≥ 38.0°C), nausea, fatigue, myalgia, arthralgia and headache. Any = occurrence of the event regardless of intensity grade or relation to the study vaccination.

Unsolicited AEs includes any AE reported in addition to those solicited during the clinical study. Also, any 'solicited' symptom with onset outside the specified period of follow-up for solicited symptoms is reported as an unsolicited adverse event. A SAE is any untoward medical occurrence that results in death, is life-threatening, requires or prolongs hospitalization, results in disability/incapacity and is a congenital anomaly/birth defect in a subject's offspring. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation to characterize and understand it. A participant was considered withdrawn if no study procedures occurred, and no follow-up or further information has been collected from the date of withdrawal or last contact.

A SAEs is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity and is a congenital anomaly/birth defect in the offspring of a study subject. AESIs are predefined (serious or non-serious) AEs of scientific and medical concern specific to the product or program, for which ongoing monitoring and rapid communication by the investigator to the sponsor can be appropriate, because such an event might warrant further investigation to characterize and understand it. A participant was considered withdrawn if no study procedures occurred, and no follow-up or further information has been collected from the date of withdrawal or last contact.