Accurate estimates of the burden of SARS-CoV-2 infection are critical to informing pandemic response. Confirmed COVID-19 case counts in the U.S. do not capture the total burden of the pandemic because testing has been primarily restricted to individuals with moderate to severe symptoms due to limited test availability. Here, we use a semi-Bayesian probabilistic bias analysis to account for incomplete testing and imperfect diagnostic accuracy. We estimate 6,454,951 cumulative infections compared to 721,245 confirmed cases (1.9% vs. 0.2% of the population) in the United States as of April 18, 2020. Accounting for uncertainty, the number of infections during this period was 3 to 20 times higher than the number of confirmed cases. 86% (simulation interval: 64–99%) of this difference is due to incomplete testing, while 14% (0.3–36%) is due to imperfect test accuracy. The approach can readily be applied in future studies in other locations or at finer spatial scale to correct for biased testing and imperfect diagnostic accuracy to provide a more realistic assessment of COVID-19 burden.

Acute malnutrition accounts for an immense disease burden and is implicated as a key, underlying cause of child mortality in low resource settings. Child wasting, defined as weight-for-length more than 2 standard deviations below international standards, is a leading indicator to measure the Sustainable Development Goal target to end malnutrition by 2030. Prevailing methods to measure wasting rely on cross-sectional surveys that are unable to measure onset, recovery, and persistence - key features of wasting epidemiology that could inform preventive interventions and disease burden estimates. Here, we show through an analysis of 18 longitudinal cohorts that child wasting is a highly dynamic process of incident onset and recovery, and that peak incidence is between birth and 3 months - far earlier than peak prevalence at 12-15 months. By age 24 months the proportion of children who had ever experienced a wasting episode (33%) was more than 5-fold higher than prevalence (6%), suggesting that the wasting burden is likely far higher than cross-sectional surveys suggest. Seasonally driven changes in population mean weight-for-length were large (>0.5 z in some cohorts) and were synchronous with rainfall across diverse settings, creating potential for seasonally targeted interventions. Our results motivate a new focus on extending preventive interventions for child wasting to pregnant and lactating mothers, and for preventive and therapeutic interventions to include children below age 6 months in addition to current targets of ages 6-59 months.

Globally 149 million children under five are estimated to be stunted (length more than 2 standard deviations below international growth standards). Stunting, a form of linear growth failure, increases risk of illness, impaired cognitive development, and mortality. Global stunting estimates rely on cross-sectional surveys, which cannot provide direct information about the timing of onset or persistence of growth failure- a key consideration for defining critical windows to deliver preventive interventions. We performed the largest pooled analysis of longitudinal studies in low- and middle-income countries to date (n=31 cohorts, 62,993 children, ages 0-24 months), allowing us to identify the typical age of linear growth failure onset and to investigate recurrent faltering in early life. The highest incidence of stunting onset occurred from birth to age 3 months. From 0 to 15 months, less than 5% of children per month reversed their stunting status, and among those who did, stunting relapse was common. Early timing and low reversal rates emphasize the importance of preventive intervention delivery within the prenatal and early postnatal phases coupled with continued delivery of postnatal interventions through the first 1000 days of life.

Child growth failure is associated with a higher risk of illness and mortality, which contributed to the United Nations Sustainable Development Goal 2.2 to end malnutrition by 2030. Current prenatal and postnatal interventions, such as nutritional supplementation, have been insufficient to eliminate growth failure in low resource settings -motivating a search for key age windows and population subgroups in which to focus future preventive efforts. Quantifying the effect of early growth failure on severe outcomes is important to assess burden and longer-term impacts on the child. Here we show through an analysis of 35 longitudinal cohorts (108,336 children) that maternal and child characteristics at birth accounted for the largest attributable differences in growth. Yet, postnatal growth failure was larger than differences at birth, and characteristics of the child's household environment were additional determinants of growth failure after age 6 months. Children who experienced early ponderal or linear growth failure were at much higher risk of persistent growth failure and were 2.0 to 4.8 times more likely to die by age 24 months. High attributable risk from prenatal causes, and severe consequences for children who experienced early growth failure, support a focus on pre-conception and pregnancy as key opportunities for new preventive interventions. Our results suggest that broad improvements in wellbeing will be necessary to eliminate growth failure in low resource settings, but that screening based on weight could help identify children at highest risk of death before age 24 months.

We sought to comprehensively assess the prevalence and outcomes of complications associated with Staphylococcus aureus bacteremia (SAB) in children. Secondarily, prevalence of methicillin resistance and outcomes of complications from methicillin-resistant S. aureus (MRSA) vs. methicillin-susceptible S. aureus SAB were assessed. This is a single-center cross-sectional study of 376 patients ⩽18 years old with SAB in 1990-2014. Overall, 197 (52%) patients experienced complications, the most common being osteomyelitis (33%), skin and soft tissue infection (31%), and pneumonia (25%). Patients with complications were older (median 3 vs. 0·7 years, P = 0·05) and more had community-associated SAB (66% vs. 34%, P = 0·001). Fewer patients with complications had a SAB-related emergency department or hospital readmission (10% vs. 19%, P = 0·014). Prevalence of methicillin resistance increased from 1990-1999 to 2000-2009, but decreased in 2010-2014. Complicated MRSA bacteremia resulted in more intensive care unit admissions (66% vs. 47%, P = 0·03) and led to increased likelihood of having ⩾2 foci (58% vs. 26%, P < 0·001). From multivariate analysis, community-associated SAB increased risk and concurrent infections decreased risk of complications (odds ratio (OR) 1·82 (1·1-3·02), P = 0·021) and (OR 0·58 (0·34-0·97), P = 0·038), respectively. In conclusion, children with SAB should be carefully evaluated for complications. Methicillin resistance remains associated with poor outcomes but have decreased in overall prevalence.