Safety and Immunogenicity of Measles Vaccine, Varicella Vaccine and Hepatitis-A Vaccine

This trial will evaluate the safety and immunogenicity of: i) measles vaccine (CAM-70) after primary dose at 6 months (MV1) and booster vaccination at 12 months (MV2); ii) a single dose of varicella vaccination at 18 months; and iii) a single dose of hepatitis-A vaccination at 18 months in HIV-exposed and HIV-unexposed South African children.

Measles vaccine (MV) can reduce childhood mortality and is currently recommended to all South African children aged 6 months. Only one study has examined the safety and immunogenicity of the recommended CAM-70 measles vaccine strain in children under 9 months of age. In addition, there are limited data on the safety and immunogenicity of varicella vaccine (VV) and Hepatitis-A vaccination (Hep-AV) in HIV-exposed and HIV-unexposed children in Sub-Saharan Africa.

This is a prospective, observational cohort study nested within a larger randomized, open-label trial on pneumococcal-conjugate vaccine (PCV) titled PCV1+1. 70 HIV-exposed and 200 HIV-unexposed children will be enrolled at Chris Hani Baragwanath Academic Hospital (CHBAH) and neighbouring primary health clinics.

Immune responses to the vaccines will be measured as rate of seroconversion, rate of seroprotection, and geometric mean titres (GMT) one month post primary immunization (MV1, VV, Hep-AV) and one month post booster dose (MV2). In addition, pre-vaccination and medium long-term antibody levels at 4.5 months, 12 months and 18 months will be evaluated. Number of adverse events in all immunized infants will be recorded throughout the study duration and compared between groups. Long-term antibody levels at 3, 4 and 5 years of age will be measured during annual follow-up visits.

This study will add to the current evidence on immunizing infants with MV (CAM-70) at 6 and 12 months of age. Data will be stratified by HIV-exposure and HIV-infection, thereby offering insight in the influence of HIV on post-vaccination immune responses. The findings on VV/Hep-AV safety, immunogenicity and seroprevalence will be useful to informing future immunization policies in Sub-Saharan Africa.

Eligibility Criteria:
Inclusion Criteria:

1. Aged ≤18 weeks;
2. Parent/guardian able to provide informed consent;
3. Available for the duration of the study;
4. Enrolled as a participant in the PVC1+1 trial AND born to HIV-uninfected woman; OR Born to HIV-infected mother AND infant CD4% ≥25% if HIV-infected;
5. Birth weight \>2499g AND weight of \>3.5 kg at time of proposed enrolment;
6. Being a healthy child (except for HIV status in HIV-exposed cohort) based on medical history and physical examination by the study staff.

Exclusion Criteria:

1. Significant major congenital abnormalities;
2. Received measles vaccination, varicella vaccination or hepatitis-A vaccination since birth;
3. Previous hospitalization for respiratory illness following discharge from hospital at birth;
4. Known allergy to vaccine components;
5. Febrile illness (axillary temperature ≥37.8°C) at time of screening;
6. Known or suspected immunodeficiency condition other than HIV;
7. Planning to relocate outside of the study area during the study period;
8. Receipt of blood transfusion or any other blood products (including immunoglobulins) since birth, receipt of such products during the course of the study will require withdrawal of the child from the study;
9. History of confirmed measles, varicella or hepatitis-A disease since birth.