Safety and Immunogenicity of a ChAd155-Vectored Respiratory Syncytial Virus Vaccine in Infants 6-7 Months of age: A Phase 1/2 Randomized Trial

BACKGROUND

Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in infants. This phase 1/2, observer-blind, randomized, controlled study assessed the safety and immunogenicity of an investigational chimpanzee-derived adenoviral vector RSV vaccine (ChAd155-RSV, expressing RSV F, N, and M2-1) in infants.

METHODS

Healthy 6- to 7-month-olds were 1:1:1-randomized to receive 1 low ChAd155-RSV dose (1.5 × 1010 viral particles) followed by placebo (RSV_1D); 2 high ChAd155-RSV doses (5 × 1010 viral particles) (RSV_2D); or active comparator vaccines/placebo (comparator) on days 1 and 31. Follow-up lasted approximately 2 years.

RESULTS

Two hundred one infants were vaccinated (RSV_1D: 65; RSV_2D: 71; comparator: 65); 159 were RSV-seronaive at baseline. Most solicited and unsolicited adverse events after ChAd155-RSV occurred at similar or lower rates than after active comparators. In infants who developed RSV infection, there was no evidence of vaccine-associated enhanced respiratory disease (VAERD). RSV-A neutralizing titers and RSV F-binding antibody concentrations were higher post-ChAd155-RSV than postcomparator at days 31, 61, and end of RSV season 1 (mean follow-up, 7 months). High-dose ChAd155-RSV induced stronger responses than low-dose, with further increases post-dose 2.

CONCLUSIONS

ChAd155-RSV administered to 6- to 7-month-olds had a reactogenicity/safety profile like other childhood vaccines, showed no evidence of VAERD, and induced a humoral immune response. Clinical Trials Registration. NCT03636906.

Factors Associated with the Duration of Breastfeeding: The Practices of Mexican Mothers in a Megacity and in the Agricultural Town

BACKGROUND

Breast milk is irreplaceable for healthy development. In Mexico, by 2019, the prevalence of exclusive breastfeeding (EBF) was low and the use of breastmilk substitutes (BMSs) was high.

OBJECTIVE

The aim of this work was to evaluate the maternal and child characteristics related to breastfeeding (BF) duration and to the introduction of BMSs for residents of Mexico City (CdMX) and an agricultural town in Morelos.

METHODS

A cross-sectional study was conducted with 160 mother-child binomials (0-15 months of age) from the megacity CdMX and the agricultural town.

OUTCOMES

EBF and total breastfeeding (TBF) duration, age of transition to BMSs, and the introduction of complementary feeding (CF) were assessed. Associations with maternal and infant factors were assessed using Cox models.

RESULTS

The prevalence of EBF in the joint samples at 5.9 months was 32.6% and 5.8% at 6 months. EBF was favored under the following conditions: living in CdMX, receiving prenatal care, no newborn hospitalization, and breastmilk provided as first food at birth. TBF was prolonged under the following conditions: older mother, female children, rooming-in care during puerperium, receiving BF upon discharge after birth, cohabiting with extended family, and having no siblings. The introduction of BMSs predominated under the following conditions: living in an agricultural town, BMSs given after birth before discharge, younger mother, worker mother, and lack of prenatal care. The early introduction of CF (before the fourth month) was 2% for CdMX and 14% for the agricultural town.

CONCLUSIONS

The agricultural population had a higher risk of the premature interruption of EBF/TBF and the early introduction of BMSs and CF. Protective factors were family-friendly environments and being born in a baby-friendly hospital.

Clinical and Epidemiological Characteristics of Paediatric Patients Diagnosed with COVID-19 in a Tertiary Hospital in Mexico City

COVID-19 affects the paediatric population less frequently than adults. A retrospective study was performed in a tertiary paediatric hospital in Mexico City in children <18 years of age who were hospitalized with a positive reverse transcription-polymerase chain reaction for SARS-CoV-2. Included in the study were 86 patients with a median age of 10 years old (IQR 2.6-14.3 years), who were classified in three groups: previously healthy, with chronic disease and immunosuppressed patients. The principal signs and symptoms were fever (81%), cough (51%) and headache (35%). A total of 20 patients (23%) required management in the paediatric intensive care unit (PICU) and 17% needed mechanical ventilation for an average of 12.7 days (IQR 2-29 days). There was no statistically significant difference between the three clinical classification groups in those patients admitted to the PICU, most of which were previously healthy patients. The mortality rate was 5% (four patients). Given that the paediatric population is susceptible to infection, potential transmitters and to clinical presentations with variable degrees of severity, it is important to continue reinforcing social distancing measures.