A Study on the Safety and Immune Response to an Unadjuvanted RSV Maternal Vaccine, in High Risk Pregnant Women Aged 15 to 49 Years and Infants Born to the Vaccinated Mothers

Phase 3

Terminated

Conditions: Respiratory Syncytial Virus Infections

Interventions: Biological: RSV MAT
Drug: Placebo

Registration Number: NCT04980391

Lead Sponsor: GlaxoSmithKline

Brief Summary: The purpose of this study was to evaluate the safety, reactogenicity and immune response of a single intramuscular dose of the respiratory syncytial virus (RSV) maternal vaccine compared to placebo, when administered in the second or third trimester of pregnancy in women, 15 to 49 years of age (YOA), with high risk pregnancies and in the infants born to the vaccinated mothers.

Following a recommendation from the Independent Data Monitoring Committee of NCT04605159 (RSV MAT 009), GSK made the decision to stop enrolment and vaccination in the study. Ongoing study participants at that time continued to be monitored as part of the study.

Detailed Description: Not available

Recruitment & Eligibility

Status: TERMINATED

Sex: Female

Target Recruitment: 384

Inclusion Criteria

Maternal participants

Participants who can and will comply with the requirements of the protocol.
Participants and LARs who give written or witnessed/thumb printed informed consent after the study has been explained according to local regulatory requirements, and before any study specific procedures are performed. The informed consent given at screening should either:
- include consent for both the maternal participant's participation* and participation of the infant after the infant's birth, or
- include consent for the maternal participant's participation* and expressed willingness to consider permitting the infant to take part after the infant's birth (if local regulations/guidelines require parent(s) to provide an additional informed consent after the infant's birth).
- both mother and father should consent if local regulations / guidelines require it.
Pre-pregnancy Body Mass Index (based on participant's report) 18.5 to 39.9 kg/m^2, inclusive.
Healthy adolescent pregnant women, 15 to 17 YOA, inclusive, at the time of study intervention administration.

Pregnant women, 18 to 49 YOA, inclusive, at the time of study intervention administration with:
- HIV infection AND/OR
- Obstetric complications or risk factors during the current pregnancy, where the expectant management of the pregnancy is possible and without evidence of non-reassuring fetal status (only cases for which fetal heart rate can be ascertained) as follows:
- Gestational diabetes, well-controlled on medications (with or without diet or exercise)
- Gestational hypertension, well-controlled on diet or medications below 160/110 mmHg.
- Pre-eclampsia without severe features (i.e. eclampsia, severe hypertension [>160/110 mmHg], organ dysfunction, unstable or complicated by [HELLP] syndrome).
- Fetal Growth Restriction in singleton pregnancies, with normal umbilical artery Doppler and estimated fetal weight 3 to 10th percentile for gestational age.
- History of threatened preterm labor in the current pregnancy, with no cervical dilation greater than 2 cm or effacement exceeding 50%, and/or no progressive change in cervical dilation or effacement detected by serial examinations, when maternal participant is asymptomatic
- Uncomplicated twin gestation.
Pregnant females at 24^0/7 to 36^0/7 weeks of gestation at the time of study intervention administration (Day 1), as established by:
- Last menstrual period (LMP) date corroborated by first or second trimester ultrasound examination (U/S) (i.e. at or before 28 weeks of gestation).
- First or second trimester U/S only, if LMP is unknown/uncertain.
- Certain LMP, corroborated by an U/S performed after 28 weeks of gestation is also acceptable.

The level of diagnostic certainty of the gestational age should be established by using the Global Alignment of Immunization Safety Assessment in pregnancy (GAIA) gestation age assessment tool

Participants who are willing to provide cord blood.
Willing to have their offspring followed-up after delivery for a period of 12 months.
Participants who do not plan to give their offspring for adoption or place the child in care.

Note that women whose pregnancies resulted from Assisted Reproductive Technologies may be enrolled if they meet all inclusion criteria and none of the exclusion criteria.

Infant participants

Live-born from the study pregnancy.
If required per local regulations / guidelines, re-signed (confirmed) written or witnessed/thumb printed informed consent for study participation of the infant obtained from the infant's mother and/or father and/or LAR, before performing any infant study specific procedure. To comply with RTI surveillance and other protocol required procedures that begin immediately after birth: if written consent cannot be provided by the parent(s)/LAR(s) readily post-birth, verbal consent - if permitted per local regulation -- may be sought from the parent(s) / LAR(s) instead. Verbal consent should be documented in the source data by the investigator or delegate. The parent(s) / LAR(s) will provide additional, written informed consent by (or before) Visit 2-NB.

Exclusion Criteria

Maternal participants Medical conditions

History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention.
Hypersensitivity to latex.
Any pre-existing medical conditions or obstetric complications in the current pregnancy that, are poorly controlled and/or with clinical evidence of a non-reassuring fetal status and/or are likely to result in delivery within 7 days after study intervention administration and/or when the timing of planned delivery is within 7 days after study intervention administration and/or acute conditions requiring immediate medical attention for maternal stabilization and/or treatment.
A multiple pregnancy with 3 or more fetuses.
Complicated twin gestation.
Placenta Accreta Spectrum, including placenta increta, percreta, and accreta.
Fetal structural defects or genetic abnormalities that affect (or are likely to affect) fetal health or survival during the first year of life.
Known or suspected impairment of the immune system or immunodeficiency syndrome other than HIV.
Lymphoproliferative disorder or malignancy within 5 years before study dose administration.
Any illness of the mother or conditions of the fetus that, may substantially interfere with the maternal participant's ability to comply with study procedures, or could increase the risks to the mother or the fetus, or could preclude the evaluation of the participant's data.
Any other clinical condition that, might pose additional risk to the participant due to participation in the study, as determined by medical history, physical examination or laboratory screening tests.
Women with any diagnosis, condition, treatment, or other factor that, has the potential to affect or confound assessments of immunogenicity or safety
Any conditions which, in the investigator's opinion, would increase the risks of study participation to the unborn infant.

Prior/Concomitant therapy

Prior receipt of an RSV maternal vaccine.
Use of any investigational or non-registered product other than the study intervention(s) during the period beginning:
- For a drug, vaccine or medical device: 29 days before the dose of study intervention(s) (Day -28 to Day 1), or their planned use during the study period.
- For immunoglobulins: 90 days before the dose of study intervention(s), or their planned use during the study period.

The exception to this is investigational products administered in the setting of a pandemic. Administration in this case should respect the same period outlined above prior to study intervention administration, but may be allowed following delivery.

Planned administration/administration of a vaccine not foreseen by the study protocol in the period starting 29 days before the study Day 1 and ending at delivery, with the exception of seasonal influenza vaccines, tetanus vaccines, dTpa/Tdap - alone vaccines, dTpa/Tdap vaccines that also contain other antigens and Hepatitis B vaccines, all of which may be administered according to standard of care ≥ 15 days before or after study intervention (Day 1).
Receipt of blood or plasma products or immunoglobulin, from 90 days before study intervention administration, or planned receipt through delivery, with the exception of Rho(D) immunoglobulin, which can be given at any time. In that sense, COVID-19 vaccines may be allowed, when administered ≥ 15 days before or after study vaccination.
Administration of immune-modifying therapy within 6 months before study intervention administration, or planned administration through delivery, except if it is part of management of HIV infection.

Prior/Concurrent clinical study experience

• Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational intervention.

Other exclusions

Alcoholism or substance use disorder within the past 24 months based on the presence of 2 or more of the following abuse criteria: hazardous use, social/interpersonal problems related to use, neglect of major roles to use, withdrawal, tolerance, use of larger amounts or longer, repeated attempts to quit or control use, much time spent using, physical or psychological problems related to use, activities given up to use, craving.
A local condition that precludes injection of the study vaccine/product or precludes assessment of local (administration site) reactogenicity.
Consanguinity of maternal participant and her partner.
Any study personnel or their immediate dependents, family, or household members.

Infant participants

Concurrently participating in another clinical trial, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational vaccine/product.
Any condition which, would increase the risks of study participation to the infant.
Child in care.

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
RSV_MAT Group	RSV MAT	Maternal participants randomized to the RSV_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Control Group	Placebo	Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.

Primary Outcome Measures

Name	Time	Method
Percentage of Infant Participants Reporting MAEs From Birth up to 180 Days Post-birth	From birth up to 180 days post-birth	An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.
Percentage of Infant Participants Reporting Any SAEs From Birth up to 365 Days Post-birth	From birth up to 365 days post-birth	An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect or resulted in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.
Percentage of Infant Participants Reporting MAEs From Birth up to 365 Days Post-birth	From birth up to 365 days post-birth	An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.
RSV MAT Immunoglobulin G (IgG)-Specific Antibody Concentrations for Maternal Participants at Pre-dosing (Day 1)	At pre-dosing (Day 1)	RSV MAT IgG-specific antibody concentrations were determined by enzyme-linked immunosorbent assay (ELISA) and expressed as geometric mean concentrations (GMCs) in ELISA units per milliliter (ELU/mL).
RSV-A Neutralizing Titers for Maternal Participants at Pre-dosing (Day 1)	At pre-dosing (Day 1)	RSV-A neutralizing titers were determined by neutralization assay and expressed as geometric mean titers (GMTs).
Percentage of Maternal Participants Reporting Any Solicited Systemic Events	From Day 1 to Day 7 included	Assessed solicited systemic events included abdominal pain, diarrhea, fatigue, headache, nausea, fever \[temperature equal to or above (\>=) 38 degrees Celsius (°C)/100.4 degrees Fahrenheit (°F), regardless of the location of measurement\] and vomiting. Any = occurrence of the adverse event regardless of intensity grade or relation to study vaccination.
Percentage of Maternal Participants Reporting Any Unsolicited Adverse Events (AEs)	From Day 1 to Day 30 included	An unsolicited AE was defined as 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 was reported as an unsolicited AE. Any = occurrence of any unsolicited AE regardless of intensity grade or relation to vaccination.
Percentage of Maternal Participants Reporting Any Serious Adverse Events (SAEs) From Day 1 up to 42 Days Post-delivery	From Day 1 up to 42 days post-delivery, an average of 2 months	An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect in the offspring of a study participant or resulted in abnormal pregnancy outcomes or in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.
Number of Maternal Participants Reporting (S)AEs Leading to Study Withdrawal From Day 1 up to 42 Days Post-delivery	From Day 1 up to 42 days post-delivery, an average of 2 months	A participant was considered to have withdrawn from the study if no new study procedure had been performed or no new information had been collected for her since the date of withdrawal/last contact. (S)AEs leading to study withdrawal were (S)AEs identified by the investigator to cause participant withdrawal until the resolution of the event. These participant withdrawals were considered different from participant withdrawals for other reasons.
Percentage of Maternal Participants Reporting Medically Attended Adverse Events (MAEs) From Day 1 up to 42 Days Post-delivery	From Day 1 up to 42 days post-delivery, an average of 2 months	An MAE was defined as an unsolicited AE for which the participant received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.
Percentage of Live Births With no Congenital Anomalies, Live Births With Minor Congenital Anomaly(Ies) and Live Births With at Least 1 Major Congenital Anomaly	From Day 1 up to 42 days post-delivery, an average of 2 months	The percentage of live births with no congenital anomalies, live births with minor congenital anomaly(ies) only and live births with at least 1 major congenital anomaly is reported.
Percentage of Maternal Participants Reporting Any Solicited Administration Site Events	From Day 1 to Day 7 included	Assessed solicited administration site events included erythema, pain and swelling. Any pain = occurrence of the symptom regardless of intensity grade. Any erythema and swelling = symptom reported with a surface diameter greater than or equal to 20 millimeters.
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery	From Day 1 up to 42 days post-delivery, an average of 2 months	Pregnancy-related AESIs included preterm labor, provider-initiated preterm birth, premature preterm rupture of membranes, pre-eclampsia, pre-eclampsia with severe features including eclampsia, gestational hypertension and fetal growth restriction.
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 42 Days Post-delivery	From Day 1 up to 42 days post-delivery, an average of 2 months	Worsening of pre-existing medical condition and/or obstetric complication was considered by the investigator, using clinical judgment and the following criteria: * Change in medication and/or medication dose. * Medically attended event in relation to pre-existing condition and/or obstetric complication that are outside the routine management of the condition/complication. * SAE and/or hospitalization in relation to pre-existing condition and/or obstetric complication.
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth	From birth up to 42 days post-birth, an average of 2 months	Neonatal/infant AESIs included low birth weight (below \[\<\] 2500 grams), very low birth weight (\<1500 grams), extremely low birth weight (\<1000 grams), preterm birth (\<37 weeks of gestational age), small for gestational age (weight below 10th percentile for gestational age), congenital anomalies with internal structural defects and neonatal death in a preterm live birth (gestational age equal to or above \[\>=\] 28 and \<37 weeks).
Percentage of Infant Participants Reporting Any SAEs From Birth up to 42 Days Post-birth	From birth up to 42 days post-birth, an average of 2 months	An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect or resulted in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.
Number of Infant Participants Reporting (S)AEs Leading to Study Withdrawal From Birth up to 42 Days Post-birth	From birth up to 42 days post-birth, an average of 2 months	A participant was considered to have withdrawn from the study if no new study procedure had been performed or no new information had been collected for her since the date of withdrawal/last contact. (S)AEs leading to study withdrawal were (S)AEs identified by the investigator to cause participant withdrawal until the resolution of the event. These participant withdrawals were considered different from participant withdrawals for other reasons.
Percentage of Infant Participants Reporting MAEs From Birth up to 42 Days Post-birth	From birth up to 42 days post-birth, an average of 2 months	An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.
Percentage of Infant Participants Reporting Any SAEs From Birth up to 180 Days Post-birth	From birth up to 180 days post-birth	An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect or resulted in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.
RSV MAT IgG-specific Antibody Concentrations for Maternal Participants at Delivery	At delivery	RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.
Number of Infant Participants Reporting (S)AEs Leading to Study Withdrawal From Birth up to 180 Days Post-birth	From birth up to 180 days post-birth	A participant was considered to have withdrawn from the study if no new study procedure had been performed or no new information had been collected for her since the date of withdrawal/last contact. (S)AEs leading to study withdrawal were (S)AEs identified by the investigator to cause participant withdrawal until the resolution of the event. These participant withdrawals were considered different from participant withdrawals for other reasons.
Number of Infant Participants Reporting (S)AEs Leading to Study Withdrawal From Birth up to 365 Days Post-birth	From birth up to 365 days post-birth	A participant was considered to have withdrawn from the study if no new study procedure had been performed or no new information had been collected for her since the date of withdrawal/last contact. (S)AEs leading to study withdrawal were (S)AEs identified by the investigator to cause participant withdrawal until the resolution of the event. These participant withdrawals were considered different from participant withdrawals for other reasons.
RSV-A Neutralizing Titers for Infant Participants at Delivery or Within 72 Hours After Birth	At delivery or within 72 hours after birth	RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs. The titers were measured on the cord blood sample collected at delivery, or on a blood sample collected from the infant within 72 hours after birth (if no cord blood sample could be obtained).
RSV-A Neutralizing Titers for Maternal Participants at Delivery	At delivery	RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.
Geometric Mean Ratio (GMR) Between Cord Blood and Maternal RSV MAT IgG-specific Antibody Concentrations	At delivery (for maternal participants) or within 72 hours after birth (for infant participants)	The placental transfer ratio of IgG-specific antibody concentration was determined from cord blood (or infant blood sample collected within 72 hours after birth \[if no cord blood could be obtained\]) over that of the blood sample from mother at delivery (if no blood sample was collected during delivery).
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Delivery or Within 72 Hours After Birth	At delivery or within 72 hours after birth	RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL. The antibody concentrations were measured on the cord blood sample collected at delivery, or on a blood sample collected from the infant within 72 hours after birth (if no cord blood sample could be obtained).

Secondary Outcome Measures

Name	Time	Method
Percentage of Infant Participants Reporting Medically Assessed, RSV-associated Lower Respiratory Tract Illness (LRTIs) of Any Severity and RSV-associated Severe LRTIs From Birth up to 365 Days Post-birth	From birth up to 365 days post-birth	An RSV-associated LRTI is characterized by a history of cough OR difficulty in breathing, AND a blood oxygen saturation by pulse oximetry (SpO2) lower than (\<) 95%, OR respiratory rate increase AND a confirmed RSV infection. An RSV-associated severe LRTI meets the case definition of RSV-LRTI AND is additionally characterized by a SpO2 \<93%, OR lower chest wall in-drawing, OR inability to feed, OR failure to respond/unconscious.
RSV MAT IgG-specific Antibody Concentrations for Maternal Participants at Day 31 Post-dosing	At Day 31 post-dosing	RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.
RSV-A Neutralizing Titers for Maternal Participants at Day 31 Post-dosing	At Day 31 post-dosing	RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.
RSV-A Neutralizing Titers for Infant Participants at Day 181 Post-birth	At Day 181 post-birth	RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.
RSV-B Neutralizing Titers for Infant Participants at Day 43 Post-birth	At Day 43 post-birth	RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.
RSV-B Neutralizing Titers for Infant Participants at Day 121 Post-birth	At Day 121 post-birth	RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.
RSV-B Neutralizing Titers for Infant Participants at Day 181 Post-birth	At Day 181 post-birth	RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.
Percentage of Maternal Participants Reporting Any SAEs From Day 1 up to 180 Days Post-delivery	From Day 1 up to 180 days post-delivery	An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect in the offspring of a study participant or resulted in abnormal pregnancy outcomes or in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.
Number of Maternal Participants Reporting (S)AEs Leading to Study Withdrawal From Day 1 up to 180 Days Post-delivery	From Day 1 up to 180 days post-delivery	A participant was considered to have withdrawn from the study if no new study procedure had been performed or no new information had been collected for her since the date of withdrawal/last contact. (S)AEs leading to study withdrawal were (S)AEs identified by the investigator to cause participant withdrawal until the resolution of the event. These participant withdrawals were considered different from participant withdrawals for other reasons.
Percentage of Maternal Participants Reporting MAEs From Day 1 up to 180 Days Post-delivery	From Day 1 up to 180 days post-delivery	An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 180 Days Post-delivery	From Day 1 up to 180 days post-delivery	Worsening of pre-existing medical condition and/or obstetric complication was considered by the investigator, using clinical judgement and the following criteria: * Change in medication and/or medication dose. * Medically attended event in relation to pre-existing condition and/or obstetric complication that are outside the routine management of the condition/complication. * SAE and/or hospitalization in relation to pre-existing condition and/or obstetric complication.
Percentage of Infant Participants Reporting Medically Assessed, RSV-associated Hospitalizations From Birth up to 365 Days Post-birth	From birth up to 365 days post-birth	RSV-associated hospitalization was defined as a confirmed RSV infection and hospitalized for acute medical condition. Hospitalization was defined as admission for observation or treatment based on the judgment of a health care provider.
Number of Maternal Participants Reporting RSV-associated Medically Attended Respiratory Tract Illnesses (MA-RTIs) From Day 1 up to 180 Days Post-delivery	From Day 1 up to 180 days post-delivery	RSV-associated MA-RTI was defined as a medically attended visit for RTI symptoms and confirmed RSV infection.
RSV-A Neutralizing Titers for Infant Participants at Day 43 Post-birth	At Day 43 post-birth	RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.
RSV-B Neutralizing Titers for Maternal Participants at Pre-dosing (Day 1), Day 31 Post-dosing and Delivery	At pre-dosing (Day 1), Day 31 post-dosing and delivery	RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.
RSV-B Neutralizing Titers for Infant Participants at Delivery or Within 72 Hours After Birth	At delivery or within 72 hours after birth	RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs. The titers were measured on the cord blood sample collected at delivery, or on a blood sample collected from the infant within 72 hours after birth (if no cord blood sample could be obtained).
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Day 43 Post-birth	At Day 43 post-birth	RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Day 121 Post-birth	At Day 121 post-birth	RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Day 181 Post-birth	At Day 181 post-birth	RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.
RSV-A Neutralizing Titers for Infant Participants at Day 121 Post-birth	At Day 121 post-birth	RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.