Nations with more urban populations and strong international travel links were worst affected by the pandemic, the study shows.

Mortality rates and levels of restrictions — such as lockdowns and travel bans — were found to be lowest in countries previously thought to be at greatest risk from Covid-19.

A team of researchers from the NIHR Global Health Research Unit Tackling Infections to Benefit Africa (TIBA) from the University of Edinburgh worked with the World Health Organization (WHO) African Region to identify factors affecting mortality rates during Africa’s first two Covid-19 waves and the timing of the first reported cases.

Professor Mark Woolhouse, TIBA Director, who co-led the study, said: “Our study shows very clearly that multiple factors influence the extent to which African countries are affected by Covid-19. These findings challenge our understanding of vulnerability to pandemics.

“Our results show that we should not equate high levels of preparedness and resilience with low vulnerability.

“That seemingly well-prepared, resilient countries have fared worst during the pandemic is not only true in Africa; the result is consistent with a global trend that more developed countries have often been particularly hard hit by Covid-19.”

Among 44 countries of the WHO African Region with available data, South Africa had the highest mortality rate during the first wave between May and August 2020, at 33.3 deaths recorded per 100,000 people. Cape Verde and Eswatini had the next highest rates at 17.5 and 8.6 deaths per 100,000, respectively. At 0.26 deaths recorded per 100,000, the lowest mortality rate was in Uganda.

South Africa also recorded the highest mortality rate during the second wave between December 2020 and February 2021, at 55.4 deaths per 100,000. Eswatini and Botswana recorded rates of 39.8 and 17.7 deaths per 100,000, respectively. The lowest rate was in Mauritius, which recorded no deaths during the second wave.

“The early models which predicted how Covid-19 would lead to a massive number of cases in Africa were largely the work of institutions not from our continent. This collaboration between researchers in Africa and Europe underlines the importance of anchoring analysis on Africa’s epidemics firmly here,” said Dr. Matshidiso Moeti, WHO Regional Director for Africa and co-author. We can no longer focus our understanding of disease transmission purely on the characteristics of a virus — Covid-19 operates within a social context which has a major impact on its spread.”

As well as those with large urban populations and strong international travel links, countries with high rates of HIV were also more likely to have higher mortality rates. This may be because people with HIV often have other health conditions that put them at greater risk from Covid-19, the team suggests.

The weak link between mortality rate and the timing or severity of government-imposed restrictions on day-to-day activities is shows the impact of the wide range of application and enforcement of these restrictions across the region, making a consistent impact pattern difficult to discern. Restrictions during peaks of infection are well documented to have interrupted transmission in the region.

The findings show that the earliest recorded cases of Covid-19 were in counties where most people live in urban areas, with strong international travel links and greater testing capacity. Algeria was the first of 47 African countries to report a case, on 25 February 2020. Most countries had recorded cases by late March 2020, with Lesotho the last to report one, on 14 May 2020.

Researchers document higher deaths during the second wave, as compared to the first. The peak of infections during the second wave was also higher, with 675 deaths across the continent on 18 January 2021 compared with 323 during the first wave peak on 5 August 2020. Potential under-reporting was accounted for in the analysis.

Dr Sarah Puddicombe, NIHR’s Assistant Director for Global Health Research, said: “This study offers compelling results which challenge accepted views of epidemic preparedness and resilience in Africa. It is one of a series of important contributions that the TIBA partnership, working with governments and the WHO Regional Office has made to inform local, national and pan-African responses to the Covid-19 pandemic.”

The study, published in the journal Nature Medicine, was supported by the UK National Institute for Health Research and the Darwin Trust of Edinburgh. It also involved researchers from the Universities of Nairobi, Ghana and Hong Kong.

While risk factors for hospitalization and poor outcomes are well documented in adults, less is known about the clinical factors associated with COVID disease severity in children.

In an effort to aid mitigation strategies for children who are at high risk of developing severe COVID disease, a group of physicians at Monroe Carell Jr. Children’s Hospital at Vanderbilt studied data from 45 children’s hospitals around the country — 20,000 patients were included.

“This is one of the largest multicenter studies of children with COVID-19 in the United States,” said James Antoon, MD, PhD, FAAP, assistant professor of Pediatrics at Children’s Hospital and lead author of the study.

“And given the recent, concerning increases in COVID cases nationwide and the fact that the vast majority of children remain unvaccinated and susceptible, these findings should be taken into account when considering preventive strategies in schools and planning vaccinations when available for children less than 12 years of age,” he said.

The study, “Factors Associated with COVID-19 Disease Severity in U.S. Children,” published in the Journal of Hospital Medicine, determined the factors associated with severe disease and poor health outcomes among children presenting to the hospital with COVID. These included older age and chronic co-morbidities such as obesity, diabetes and neurologic conditions, among others.

“These factors help identify vulnerable children who are most likely to require hospitalization or develop severe COVID-19 disease,” said Antoon. “Our findings also highlight children who should be prioritized for COVID-19 vaccines when approved by the FDA.”

The retrospective cohort study noted that approximately 1 out of every 4 children admitted to the hospital with COVID developed severe disease and required ICU care during April and September, 2020.

“Across the country there is a raging debate on how best to protect children and schools from COVID-19,” said Antoon. “Some children are at increased risk for more severe disease and many of them are not yet eligible for vaccination against COVID.

“With schools opening and some already in session, these children need to be protected by vaccinating as many people as possible while also using practical strategies to limit spread, such as masking, distancing and ventilation.”

Study investigators hope that the findings will buoy mitigation efforts that proved most beneficial for children and adolescents during the pandemic, including remote learning, social distancing, hand-washing and mask-wearing both for students and teachers.

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Materials provided by Vanderbilt University Medical Center. Original written by Jessica Pasley. Note: Content may be edited for style and length.

Early in the pandemic, COVID-19 outbreaks from choir performances indicated that singing carries a potential infection risk, but less is known about the risks of airborne infection from wind instruments. To help keep performers, audiences and music students safe, Tehya Stockman, Shelly Miller and colleagues wanted to examine aerosol production and flow from various musical activities, as well as test different mitigation strategies.

The researchers examined the extent and velocity of air jets, or plumes, coming from singers’ and actors’ mouths and from wind instruments, such as the flute, clarinet, trumpet and saxophone. They also measured airborne respiratory particles, or aerosols, and carbon dioxide levels emanating from the performers. They found that aerosol concentrations coming from the bell of a clarinet were comparable to singing. Placing a surgical mask over a singer’s face or over the clarinet bell substantially reduced plume velocities and lengths and decreased aerosol concentrations in front of the masks. The team then used these measurements to model viral transmission in indoor and outdoor environments, finding that the lowest risk of airborne COVID-19 infection occurred at less than 30 minutes of exposure indoors and less than 60 minutes outdoors. These findings could help musical rehearsals and performances resume in a safer manner for musicians and audiences, the researchers say.

The authors acknowledge funding from an international coalition of more than 95 musical organizations.

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Materials provided by American Chemical Society. Note: Content may be edited for style and length.

Not indoors, say researchers in the Penn State Department of Architectural Engineering. The team found that indoor distances of two meters — about six and a half feet — may not be enough to sufficiently prevent transmission of airborne aerosols. Their results were made available online ahead of the October print edition of Sustainable Cities and Society.

“We set out to explore the airborne transport of virus-laden particles released from infected people in buildings,” said Gen Pei, first author and doctoral student in architectural engineering at Penn State. “We investigated the effects of building ventilation and physical distancing as control strategies for indoor exposure to airborne viruses.”

The researchers examined three factors: the amount and rate of air ventilated through a space, the indoor airflow pattern associated with different ventilation strategies and the aerosol emission mode of breathing versus talking. They also compared transport of tracer gas, typically employed to test leaks in air-tight systems, and human respiratory aerosols ranging in size from one to 10 micrometers. Aerosols in this range can carry SARS-CoV-2.

“Our study results reveal that virus-laden particles from an infected person’s talking — without a mask — can quickly travel to another person’s breathing zone within one minute, even with a distance of two meters,” said Donghyun Rim, corresponding author and associate professor of architectural engineering. “This trend is pronounced in rooms without sufficient ventilation. The results suggest that physical distance alone is not enough to prevent human exposure to exhaled aerosols and should be implemented with other control strategies such as masking and adequate ventilation.”

The researchers found that aerosols traveled farther and more quickly in rooms with displacement ventilation, where fresh air continuously flows from the floor and pushes old air to an exhaust vent near the ceiling. This is the type of ventilation system installed in most residential homes, and it can result in a human breathing zone concentration of viral aerosols seven times higher than mixed-mode ventilation systems. Many commercial buildings use mixed-mode systems, which incorporate outside air to dilute the indoor air and result in better air integration — and tempered aerosol concentrations, according to the researchers.

“This is one of the surprising results: Airborne infection probability could be much higher for residential environments than office environments,” Rim said. “However, in residential environments, operating mechanical fans and stand-alone air cleaners can help reduce infection probability.”

According to Rim, increasing the ventilation and air mixing rates can effectively reduce the transmission distance and potential accumulation of exhaled aerosols, but ventilation and distance are only two options in an arsenal of protective techniques.

“Airborne infection control strategies such as physical distancing, ventilation and mask wearing should be considered together for a layered control,” Rim said.

The researchers are now applying this analysis technique to various occupied spaces, including classrooms and transportation environments.

Mary Taylor, a graduate student at Penn State at the time of the research, also contributed to this work, which was supported by the National Science Foundation.

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Materials provided by Penn State. Original written by Ashley J. WennersHerron. Note: Content may be edited for style and length.

The term ‘DNA’ immediately calls to mind the double-stranded helix that contains all our genetic information. But the individual units of its two strands are pairs of molecules bonded with each other in a selective, complementary fashion. Turns out, one can take advantage of this pairing property to perform complex mathematical calculations, and this forms the basis of DNA computing.

Since DNA has only two strands, performing even a simple calculation requires multiple chemical reactions using different sets of DNA. In most existing research, the DNA for each reaction are added manually, one by one, into a single reaction tube, which makes the process very cumbersome. Microfluidic chips, which consist of narrow channels etched onto a material like plastic, offer a way to automate the process. But despite their promise, the use of microfluidic chips for DNA computing remains underexplored.

In a recent article — made available online in ACS Nano on 7 July 2021 and published in Volume 15 Issue 7 of the journal on 27 July 2021 — a team of scientists from Incheon National University (INU), Korea, present a programmable DNA-based microfluidic chip that can be controlled by a personal computer to perform DNA calculations. “Our hope is that DNA-based CPUs will replace electronic CPUs in the future because they consume less power, which will help with global warming. DNA-based CPUs also provide a platform for complex calculations like deep learning solutions and mathematical modelling,” says Dr. Youngjun Song from INU, who led the study.

Dr. Song and team used 3D printing to fabricate their microfluidic chip, which can execute Boolean logic, one of the fundamental logics of computer programming. Boolean logic is a type of true-or-false logic that compares inputs and returns a value of ‘true’ or ‘false’ depending on the type of operation, or ‘logic gate,’ used. The logic gate in this experiment consisted of a single-stranded DNA template. Different single-stranded DNA were then used as inputs. If part of an input DNA had a complementary Watson-Crick sequence to the template DNA, it paired to form double-stranded DNA. The output was considered true or false based on the size of the final DNA.

What makes the designed chip extraordinary is a motor-operated valve system that can be operated using a PC or smartphone. The chip and software set-up together form a microfluidic processing unit (MPU). Thanks to the valve system, the MPU could perform a series of reactions to execute a combination of logic operations in a rapid and convenient manner.

This unique valve system of the programmable DNA-based MPU paves the way for more complex cascades of reactions that can code for extended functions. “Future research will focus on a total DNA computing solution with DNA algorithms and DNA storage systems,” says Dr. Song.

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Materials provided by Incheon National University. Note: Content may be edited for style and length.