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Research Roundup: November 2023–January 2024

February 7, 2024

Between November 1, 2023, and January 31, 2024, Fogarty’s Division of International Epidemiology and Population Studies published nine studies on a range of topics related to domestic and international health in peer-reviewed journals.

Three articles about the impact of clean cooking interventions on child health

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Impact of clean cookstove use on rates of severe infant pneumonia

Fogarty’s Dr. Joshua Rosenthal contributed to this research study published in the New England Journal of Medicine in January 2024. Nearly 83% of 808,000 annual child deaths due to pneumonia occur in sub-Saharan Africa, South Asia, and Latin America. The Household Air Pollution Intervention Network (HAPIN) trial team compared rates of severe infant pneumonia in households using traditional cookstoves, which use biomass fuels (wood, dung, or agricultural waste) versus those using liquefied petroleum gas (LPG) cookstoves. Pregnant women in India, Guatemala, Peru, and Rwanda were assigned to receive free LPG stoves and cooking fuel (intervention group) or not and so continue with traditional stove fuels (control group). Among 3,195 women, 3,061 gave birth to live infants: 1,536 in the intervention group, 1,525 in the control group. Median personal exposure to PM2.5 (fine particulate air pollution, a probable contributor to pneumonia) among intervention children was 24.2 micrograms (μg) per cubic meter in comparison to 66.0 μg per cubic meter among control children. The authors identified 175 episodes of severe infant pneumonia—5.67 cases per 100 child-years in the intervention group and 6.06 cases per 100 child-years in the control group. There was no significant difference in severe pneumonia between groups, despite achieving major reductions in exposure to cooking smoke during the 18-month intervention period.

Impact of clean cookstove use on stunting risk in infants

A related paper co-authored by Rosenthal appeared in the New England Journal of Medicine in January. The HAPIN team explored whether replacing biomass fuels with LPG cookstoves could reduce the risk of stunted growth in infants. (Stunting has been linked to household air pollution in observational studies.) Personal exposure to fine particulate matter was monitored starting at pregnancy and continued until children were 12 months old, at which time the length of each infant was measured. The intervention resulted in lower prenatal and postnatal exposures to fine particulate matter compared to controls. Stunting occurred in 321 of the 1,171 infants (27.4%) born to women in the intervention group and in 299 of the 1,186 infants (25.2%) born to women in the control group. The LPG cooking intervention did not reduce stunting.

Impact of clean cookstove use on risk of stillbirth, congenital abnormalities, or infant death

A third HAPIN trial, coauthored by Rosenthal, was published in Environmental Pollution and investigated the effects of LPG stove and fuel intervention on stillbirth, abnormalities present at birth, and infant death. Analysis found that relative risks were 0.99 for stillbirth, 0.92 for abnormalities present at birth and 0.99 for infant death among women in the intervention arm compared to controls. Higher average personal exposures to fine particulate matter, black carbon and carbon monoxide during pregnancy were associated with a higher, but statistically non-significant, incidence of these negative outcomes. The authors found no evidence to support an association between personal exposures to household pollution and higher risk of these outcomes.

Using multiple models is best for long-term disease outbreak projections

Samantha Bents, a Fogarty research intern, and Fogarty’s Dr. Cécile Viboud contributed to this study published November 2023 in Nature Communications. A year after SARS-CoV-2 was detected in December 2019, the US COVID-19 Scenario Modeling Hub (SMH) began to produce medium- to long-term projections based on different scenarios. This evaluation of 14 rounds of projections (and comparison to the actual course of the epidemic) found that SMH performance varied widely. Though scenarios remained close to reality for 22 weeks on average, the arrival of unanticipated SARS-CoV-2 variants invalidated key model assumptions thereafter. Results suggest a collection of models that preserves variation between models is consistently more reliable than any single model for longer-term projections.

Lessons learned by the COVID-19 Scenario Modeling Hub

A second SMH paper co-authored by Bents and Viboud appeared in Epidemics in December 2023. Here, the authors describe the history of SMH’s collective research effort, which included convening and maintaining an open modeling hub over multiple years, while attempting to provide a blueprint for future efforts. The authors describe the process of generating 17 rounds of scenarios and projections at different stages of the COVID-19 pandemic and the methods of disseminating results. Among the many lessons learned is a need to expand modeling hubs to resource-limited settings. 

COVID-19 masking & behavior changes reduced RSV rates in South Africa

Bents, first author, and Viboud, co-author, published this study in Influenza and Other Respiratory Viruses in December 2023. The South African government employed various nonpharmaceutical interventions (NPIs) to reduce SARS-CoV-2 transmission. Surveillance data indicates reduced circulation of respiratory syncytial virus (RSV) throughout the 2020-2021 COVID-19 seasons. From 2020 through 2021, NPIs reduced RSV transmission up to 50% during periods of high COVID-19 circulation and, during the Omicron surge, masking and behavior changes limited transmission by 15%, the team’s models show. They project a lower peak in the 2023 season compared to 2022, but slightly larger hospital burden, driven in part by the disappearance of pandemic NPIs.

Cross-species data is useful when designing flu vaccines

This study by Fogarty’s Dr. Nidia Trovão (first author) and Dr. Josh Cherry (senior author) appeared in mBio in January 2024. Among influenza A and B viruses, both of which can cause seasonal flu, H3 and H1 subtypes of influenza A viruses infect not only humans but also many animals, thereby posing a potential pandemic threat. Hemagglutinin protein (HA), which extends from the virus' surface and is relevant to its infectiousness, is shaped like a dandelion with a head and a stalk. Traditionally, flu vaccine developers have targeted the head but knowing now that the head evolves more rapidly than the stalk, they’ve shifted their focus to this more slowly changing feature. This analysis of HA sequences from 49 lineages evolving independently in birds, swine, canines, equines, and humans reveals that the canine H3 stalk, unlike its human counterpart, evolves quickly. A multi-host perspective on HA evolution may be useful when designing stalk-targeted vaccine candidates, the team concluded.

Multiple trait subsampling improves suboptimal datasets

Trovão co-authored this study published in Virus Evolution in November 2023. The availability of public databases with genomic data has increased in recent years. Because sequences deposited in these databases are project-dependent, they don’t fairly represent the underlying population. For example, a database may collect sequences from patients with a specific condition; some traits, then, would be represented at lower or higher probability when compared to prevalence in the wider population. The researchers investigated HIV-1 Subtype C evolutionary and other dynamics while subsampling the genetic data to mitigate biases and found subsampling that includes as many traits as possible to be the best strategy for optimizing a dataset and preparing it for analysis.

Profile of cohort for SARS-CoV-2 study in Costa Rica

Fogarty’s Dr. Kaiyuan Sun co-authored this BMJ Open paper published in December 2023. Roughly 1.24 million COVID-19 cases and 9,500 associated deaths have been reported in Costa Rica, population 5.1 million, as of July 2023. The RESPIRA study (Evaluation of the immune response to SARS-CoV-2 in Costa Rica) is an international collaboration aiming to understand multiple aspects of the pandemic. Recruitment included 3,860 individuals, including 1,150 COVID-19 cases, 1,999 population controls, and 719 household contacts from 304 index cases. RESPIRA will enable multiple analyses, such as identifying infection prevalence, risk factors for SARS-CoV-2 acquisition and severity, and determinants of household transmission.

More Information

Updated February 7, 2024

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