Among African children admitted to 25 hospitals with COVID-19 between March and December 2020, infants younger than 1 year had nearly five times the risk of death than adolescents aged 15 to 19 years. Children of all ages with comorbidities, including high blood pressure, chronic lung diseases, hematological disorders and cancer, also were at higher risk of dying.

“Although our study looked at data from earlier in the pandemic, the situation hasn’t changed much for the children of Africa — if anything, it is expected to be worsening with the global emergence of the highly contagious Omicron variant,” said lead author Jean B. Nachega, M.D., Ph.D., M.P.H., associate professor of infectious diseases and microbiology and epidemiology at Pitt’s Graduate School of Public Health. “Vaccines are not yet widely available, and pediatric intensive care is not easily accessible.”

The study examined outcomes in 469 children who ranged in age from 3 months to 19 years and were hospitalized in one of six countries: the Democratic Republic of the Congo, Ghana, Kenya, Nigeria, South Africa and Uganda. A quarter of the children had pre-existing conditions. Eighteen had confirmed or suspected multisystem inflammatory syndrome, a serious complication of COVID-19 where different parts of the body become inflamed.

The study, which included investigators across all six of the African countries that provided data, found that 34.6% of hospitalized children were admitted to an intensive care unit (ICU) or required supplemental oxygen, and 21.2% of those admitted to the ICU required invasive mechanical ventilation. During the time frame studied, 39 — over 8% — of the children died. This compares with rates between 1% and 5% that have been reported in high-income countries.

“The high morbidity and mortality associated with hospitalized children with COVID-19 in our study challenge the existing understanding of COVID-19 as a mild disease in this population,” said Nachega, also a professor extraordinary of medicine at Stellenbosch University’s Faculty of Medicine and Health Sciences in Cape Town, South Africa. “But if a child has a comorbidity, is very young and is in a place where there are limited or no specialized doctors, facilities or equipment for pediatric intensive care, then that child faces a very real possibility of dying.”

“Our findings call for an urgent scale-up of COVID-19 vaccination and therapeutic interventions among at-risk eligible children and adolescents in Africa,” Nachega continued. “They also raise further the acute need for capacity-building and support for pediatric intensive care in these settings.”

Nachega noted recent progress on increasing the COVID-19 vaccine supply in Africa but emphasized that those vaccines are not yet widely available and only about 5% of the continent’s population has been fully vaccinated.

“COVID-19 vaccine hesitancy is a global issue, and Africa is no exception,” he said. “It is imperative that evidence-based public health campaigns address concerns in accessible, trustworthy ways so that there is high vaccine uptake as soon as it is available.”

Additional investigators of this study are members of the African Forum for Research and Education in Health COVID-19 Research Collaboration on Children and Adolescents and are listed in the JAMA Pediatrics article.

This research was supported by National Institutes of Health Fogarty International Center grant 1R25TW011217-01.

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The study, which examined zebrafish embryos, discovered a type of astrocyte glial cell that is new to science, and have been named estrogen responsive olfactory bulb (EROB) cells.

estrogens are known for their roles as signalling hormones in the development of sex, but the study shows that prior to sexual differentiation (when the sex of an individual becomes fixed), a small group of cells in the region of the brain where the sense of smell develops, the olfactory bulb, are responsive to estrogen.

The research, led by Dr Aya Takesono of the University of Exeter, employed a genetically engineered (transgenic) zebrafish, developed in the laboratories of Professor Tyler and Dr Kudoh at Exeter, that enables cells and tissues responding to estrogen to be seen via microscopy imaging for this work.

Using this transgenic zebrafish, together with chemical and genetic methods to manipulate these estrogen responding cells, has revealed a new function of estrogens during embryonic brain development.

Dr Takesono said: “Previous studies in mice have shown that estrogen is important for development of the somatosensory cortex of the brain and for establishing sexual dimorphic brain tissues that mediate reproductive functions and behaviour in later life.

“In this study, however, we show that the olfactory bulb is the one of earliest parts of the developing brain that is responsive to estrogens in the zebrafish embryo.

“We further show that our newly discovered EROB cells mediate the estrogen driven instruction for development of olfactory sensory system in the embryonic brain.”

Tracing the development of these EROBs using various cellular and imaging methods showed they interact with olfactory sensory neurons and their loss — or disturbance of their interactions with the surrounding neurons — disrupts establishing inhibitory neural connections in the olfactory glomeruli.

Using another transgenic zebrafish, this time one that detects both neural activity (via the detection of calcium produced when nerve cells fire) and estrogen responses, the study shows that estrogen signalling alters neuronal activity in the olfactory bulb through these newly identified EROBs which in turn affects odorant-response behaviour.

This study provides evidence that estrogens act on EROB glia to regulate olfactory circuits with important consequences for the sense of smell in later life.

Professor Tyler, senior author in the work, said: “This work identifying new embryonic brain cells involved in the development of the sense of smell in fish opens up a major new research area for us.

“Surface waters receive many human-made chemicals that mimic estrogens and an intriguing question we wish to now address is whether these chemicals affect the function of the EROB glia in embryogenesis and thus alter the sense of smell, as this could have major fitness consequences for fish.”

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According to the study, published in the journal Proceedings of the Royal Society B, coral populations of the Mediterranean — essential for the functioning of the coral reefs, one of the most emblematic habitats in this sea — could be unable to recover from the recurrent impact of these extreme episodes, with water temperatures reaching high degrees for days and even weeks.

This is the first study to assess the long-term recovery capacity of populations of two emblematic species of Mediterranean coral: the red gorgonian (Paramuricea clavata) and the red coral (Corallium rubrum), which provide complex habitats that are essential for a great diversity of associated fauna. Therefore, it is essential to understand their resilience regarding the more frequent and intense heatwaves.

Mass mortality events

The climate crisis is severely affecting the marine ecosystems worldwide, and the Mediterranean is no exception. In particular, the marine heatwaves associated to the climate crisis are causing mass mortality events in all the coastal ecosystems of this basin, and among the most affected species are the Mediterranean corals.

Knowledge on the coral’s long-term resilience is still scarce, despite the studies that analysed the immediate impact of marine heatwaves on these organisms. These are long-lived species (more than a hundred years in some cases) and with slow populational dynamics (that is, organisms with low growth and recruitment rates), and therefore researchers need long temporary series (decades) to assess their recovery capacity.

As part of the study, the team analysed the results obtained in a long-term monitoring on different populations of coral affected by a great mass mortality caused by a heatwave in 2003 in the protected marine area of Scandola (Corsega, France). In particular, they analysed data on the state of these populations (density, size structure and biomass) collected during the following fifteen years to the heatwave, by the researchers of the MedRecover research group, formed by experts of the UB and ICM-CSIC, among other centres.

Far from recovery, the results show that all the analysed populations tended to collapse since they were affected by the 2003 heatwave. Fifteen years after this event, these populations are practically considered to be extinct from a functional perspective.

“We observed an average biomass loss regarding the initial biomass of 80% in populations of red gorgonian, and up to a 93% regarding the studied population of red coral,” notes Daniel Gómez, researcher at ICM-CSIC.

“These data are worrying for the conservation of these emblematic species, and it indicates that the effects of the climate crisis are speeding up with obvious consequences for the submarine landscapes, where the loss of coral equals the loss of trees in forests,” notes Joaquim Garrabou, also member of ICM-CSIC.

Recurrent exposure to heatwaves

Cristina Linares, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology and member of IRBio, says that “we believe one of the main reasons why we observed these collapse trajectories is the potential recurrent exposure to heatwaves, incompatible with the slow populational dynamics of these species.” In particular, during the study period (2003-2018), they registered important heatwaves in at least four years: 2009, 2016, 2017, 2018.

“During these heatwaves,” continues Linares, “the temperature conditions in the studied area reached extreme levels which are incompatible with the life of these corals, which probably caused new mortality events to the decimated populations and made the recovery impossible.”

Since we expect the number and intensity of marine heatwaves to increase over the following decades due to the climate crisis, the viability of many coral populations could be seriously threatened.

“However, there will probably be some areas in the Mediterranean in which, due to several factors, the recurrence of such climate impacts may be lower. This makes it especially relevant to keep — regarding other potential impacts — these climate refuges where the trajectories of coral populations could be more positive than those observed in this study,” notes the research team.

“Nevertheless, there is an urgent need for stronger measures to be implemented against the climate crisis before the loss of biodiversity becomes irreplaceable,” conclude the experts.

This study has been carried out thanks to the support of the Regional Natural Park of Corsica, the HEATMED National Plan project (RTI2018-095346-B-485 I00), the European projects H2020, MERCES, H2020 Futurmares, Interreg MED MPA-Engage and Interreg MED MPA-Adapt.