mRNA vaccines against respiratory viruses.

PURPOSE OF REVIEW: The successes of the coronavirus disease 2019 (COVID-19) mRNA vaccines have accelerated the development of mRNA vaccines against other respiratory pathogens. The aim of this review is to highlight COVID-19 mRNA vaccine advances and provide an update on the progress of mRNA vaccine development against other respiratory pathogens. RECENT FINDINGS: The COVID-19 mRNA vaccines demonstrated effectiveness in preventing severe COVID-19 and death. H7N9 and H10N8 avian influenza mRNA vaccines have demonstrated safety and immunogenicity in phase 1 clinical trials. Numerous seasonal influenza mRNA vaccines are in phase 1-3 clinical trials. Respiratory syncytial virus (RSV) mRNA vaccines have progressed to phase 2-3 clinical trials in adults and a phase 1 clinical trial in children. A combined human metapneumovirus and parainfluenza-3 mRNA vaccines was found to be well tolerated and immunogenic in a phase 1 trial among adults and trials are being conducted among children. Clinical trials of mRNA vaccines combining antigens from multiple respiratory viruses are underway. SUMMARY: The development of mRNA vaccines against respiratory viruses has progressed rapidly in recent years. Promising vaccine candidates are moving through the clinical development pathway to test their efficacy in preventing disease against respiratory viral pathogens.

Anthropometric proxies for child neurodevelopment in low-resource settings: length- or height-for-age, head circumference or both?

Stunting (<-2 SD of length- or height-for-age on WHO growth curves) is the most used predictor of child neurodevelopmental (ND) risk. Occipitofrontal head circumference (OFC) may be an equally feasible, but more direct and robust predictor. We explored association of the two measurements with ND outcome, separately and combined, and examined if cutoffs are more efficacious than continuous measures in predicting ND risk. Infants and young children in rural Guatemala (n = 642; age range = 0.1-35.9 months) were enrolled in a prospective natural history study, and their ND was tested using the Mullen Scales of Early Learning (MSEL) longitudinally. Length- or height-for-age and OFC-for-age were calculated. We performed age-adjusted multivariable regression analyses to explore the association between 1) length or height and ND, 2) OFC and ND, and 3) both length or height and OFC combined, with ND; concurrently, predictively, and longitudinally, as continuous variables and using WHO z-score cutoffs. Continuous length- or height-for-age and OFC z-scores were more strongly associated with MSEL than the traditional -2 SD WHO cutoff. The combination of height-for-age z-score and OFC z-score was consistently, strongly associated with the MSEL Early Learning Composite concurrently (p-values 0.0004-0.11), predictively (p-value 0.001-0.07), with the exception of the 18-24 months age group which had very few records, and in the longitudinal model (p-value <0.0001-0.004). The combination of continuous length- or height-for-age and OFC shows additional utility in estimating ND risk in infants and young children. Measurement of OFC may improve precision of prediction of ND risk in infants and young children.

A prospective cohort study of head circumference and its association with neurodevelopmental outcomes in infants and young children in rural Guatemala.

Microcephaly, an anthropometric marker of reduced brain volume and predictor of developmental disability, is rare in high-income countries. Recent reports show the prevalence of microcephaly to be much higher in lower resource settings. We calculated the prevalence of microcephaly in infants and young children (n = 642; age range = 0.1-35.9 months), examined trends in occipitofrontal circumference (OFC) growth in the year after birth and evaluated the relationship between OFC and performance on the Mullen Scales of Early Learning (MSEL) in rural Guatemala. Multivariable regression analyses adjusted for age were performed: (1) a model comparing concurrent MSEL performance and OFC at all visits per child, (2) concurrent OFC and MSEL performance by age group, and (3) OFC at enrollment and MSEL at final visit by age group. Prevalence of microcephaly ranged from 10.1% to 25.0%. OFC z-score decreased for most infants throughout the first year after birth. A significant positive association between continuous OFC measurement and MSEL score suggested that children with smaller OFC may do worse on ND tests conducted both concurrently and ∼1 year later. Results were variable when analyzed by OFC cutoff scores and stratified by 6-month age groups. OFC should be considered for inclusion in developmental screening assessments at the individual and population level, especially when performance-based testing is not feasible.