Tag: covid transmission

Categories : COVID PaediatricsTags :

Chinese Study Finds Children More Likely to Spread COVID

On By ModernMedia
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By gaining access to a high quality COVID transmission data from a northern Chinese city which enforced stringent lockdowns, scientists concluded that young people were most responsible for an increase in direct and secondary infections, and also determined that county-wide lockdowns proved effective in limiting the virus’s spread.

The research study, led by Professor of Sociology Zai Liang at University of Albany, was given rare access to patient profiles and contact tracing data from every case accompanying the outbreak of the virus in Shijiazhuang from January to February in 2021. “Because of universal testing and digital tracing, the data are of high quality,” said Prof Liang, who was assisted by Sociology PhD student and lecturer Han Liu. Liu is from Shijiazhuang and has connections with that city’s CDC research centre, which enabled them to get the data.

The two UAlbany researchers, joined by two colleagues from China, published their findings in the Journal of Urban Health.

Prof Liang wrote that while individual-level contact tracing studies on the virus’s transmission and mitigation efforts have been growing, “because of limited testing capacities and risks of infringing on privacy, surveillance data used in individual-level research usually have limited representativeness.” His Shijiazhuang study, whose analysis included 99.52 percent (1028 of 1133) of the transmitted cases in Shijiazhuang, is designed “to fill this gap in the literature.”

The research examined sociodemographic factors including age, gender and socioeconomic status, postulating that “certain sociodemographic characteristics may facilitate the spread of germs by exposing the host to more social contacts.” This would include children interacting in the classroom, females having more contact with their relatives than do males, and less affluent workers working or living in overcrowded settings.

Among the study’s results are:

  • Children 0–17 years old had fewer close contacts than adults, but these led to more secondary infections: 32.1% infected children, 67.9% adults
  • Close contacts of children were 81% more likely to be infected than the contacts of those 18–49
  • Peasant workers, compared to non-manual workers, had 40% more secondary cases from the same neighbourhoods.

Prof Liang wrote, “While children have a low probability of having severe symptoms after being infected by COVID, they can seed the spread in the larger society by infecting their household members and other adults living in their neighbourhoods. These adults can then transmit the disease to their own social contacts. Future studies on how to control within-school infections are therefore urgently needed.”

Another major conclusion of the Shijiazhuang study is that timely non-pharmaceutical interventions, including restrictions on gatherings and school closures, effectively contained further infections via contact reduction, especially when implemented in small areas with the highest caseloads. Liang acknowledged that school closures did have negative ramifications for children’s education and socialisation.

Serendipitous data collection

How did Prof Liang and colleagues obtain comprehensive data not yet publicly available to others? “We heard of this COVID outbreak in this part of northern China early last year, when I was working on a proposal to study COVID. I asked Han Liu if we had connections in that city. It turned out that he is originally from Shijiazhuang and has connections with that city’s CDC research centre.

“The two researchers who collected the data agreed to join us in this effort. I am lucky to ask the right question at the right time.”

Source: University at Albany

Categories : UncategorizedTags :

By Now, Nearly All South Africans Have COVID Antibodies

On By ModernMedia
South African flag with COVID theme
Image by Quicknews

The latest COVID seroprevalence survey shows that nearly every adult in South Africa has either been vaccinated or had COVID. For many, it’s both.

The study analysed blood from over 3000 blood donors. It was conducted by the South African National Blood Service, which is responsible for blood donations in eight provinces, and the Western Cape Blood Service.

The researchers estimated that by March 2022, before the fifth wave which appears to have peaked in the last few weeks, 98% of adults had some detectable antibodies, whether from COVID or from vaccination. This means that only 2% had neither been vaccinated nor been infected.

Only 10% had been vaccinated but not infected by COVID.

Read the study

(Note: The study has been published as a preprint and has not been peer-reviewed.)

What the survey tested for

Blood samples were collected and tested from 3395 consenting donors from all provinces in mid-March 2022. While blood donors are not precisely representative of the population, the researchers have argued that the study is representative enough.

This is the first time the blood services researchers have been able to look for two types of antibodies.

One test indicates if a sample has antibodies to the nucleocapsid proteins (anti-nucleocapsid antibodies). These antibodies develop if someone is infected, but won’t develop after a person receives a vaccine only (at least not those vaccines currently available in South Africa).

The other test indicates if the sample has antibodies to the spike protein (anti-spike antibodies). These antibodies develop when someone has been infected or has been vaccinated (or both).

Using these two tests together, researchers can, for the first time, evaluate the proportion of the population that has been vaccinated and not infected.

Results

After weighting the results to reflect national demographics, the researchers found that a mere 2% of the population had neither anti-spike nor anti-nucleocapsid antibodies. These are people who have likely never had COVID nor been vaccinated.

10% had only anti-spike antibodies. These are people who were likely vaccinated, but never infected.

The researchers noted that there is “an increasing incidence of reinfection” with the omicron wave.

Blood service survey is the best we have

The blood services have been regularly testing blood samples from donors throughout the pandemic, looking at the presence of anti-nucleocapsid antibodies.

While other surveys might be more representative of the population than the blood donor ones, these have been infrequently published or published long after the survey was conducted. By contrast the blood donor surveys are relatively affordable and quick to publish. Also, as far as we are aware, it is the only survey repeatedly testing the same group of people, so that comparisons across time are possible.

Past blood surveys

The blood services’ survey from samples taken in May 2021 estimated that 47% of the adult population had previously been infected.

The next survey of blood samples was taken in November 2021 after the delta wave. This was just before the omicron wave. The researchers estimated that about 70% of people had been infected.

The latest survey indicates that about 87% of people have been infected.

The previous surveys found that levels of infection differed by province. Now these differences have “largely disappeared as prevalence appears to have saturated”.

Differences across race

There are significant differences in rates of infection when different races are compared.

The November survey showed that about 80% of black donors and 40% of white donors had been infected with COVID.

In the latest survey the proportion of white and Asian donors that only have anti-spike antibodies (indicating vaccination but no infection) was higher than black and coloured donors.

The researchers suggest that “white donors are both unusually likely to avail themselves of vaccination, and they are unusually able to avoid exposure, for instance by working predominantly from home, [and] living in smaller family units.”

Article by By James Stent. Republished from GroundUp under a Creative Commons Attribution-NoDerivatives 4.0 International License.

Source: GroundUp

Categories : COVID Medical Research & TechnologyTags :

Natural Facial Asymmetry Affects Mask Fit

On By ModernMedia
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In research published in Physics of Fluids, researchers used computer modelling investigate mask fit and found that face shape, especially natural facial asymmetry, influences the most ideal fit. The findings suggested that double masking with improperly fitted masks may not greatly improve mask efficiency and produces a false sense of security.

Using more layers results in a less porous face covering, leading to more flow forced out the sides, top, and bottom of masks with a less secure fit. Double layers increase filtering efficiency only with good mask fit, however they could also lead to difficulties in breathing.

The researchers modelled a moderate cough jet from a mouth of an adult male wearing a cloth mask over the nose and mouth with elastic bands wrapped around the ears. They calculated the maximum volume flow rates through the front of mask and peripheral gaps at different material porosity levels.

To create a more realistic 3D face shape and size, the researchers used head scan data for 100 adult male and 100 adult female heads.

Their model showed how the slight asymmetry typical in all facial structures can affect proper mask fitting. For example, a mask can have a tighter fit on the left side of the face than on the right side.

“Facial asymmetry is almost imperceivable to the eye but is made obvious by the cough flow through the mask,” explained co-author Tomas Solano, from Florida State University. “For this particular case, the only unfiltered leakage observed is through the top. However, for different face shapes, leakage through the bottom and sides of the mask is also possible.”

Producing individually customised ‘designer masks’ is not practical at large scales. Still, better masks can be designed for different populations by revealing general differences between male and female or child versus elderly facial structures and the associated air flow through masks.

Source: American Institute of Physics

Categories : COVID Diseases, Syndromes and ConditionsTags :

Vigorous Exercise and Talking Produce Similar Levels of Aerosols

On By ModernMedia
Old man jogging
Photo by Barbra Olsen on Pexels

Vigorous exercise produces a similar level of aerosol particles as speaking, but high-intensity exercise produces more, according to new research published in Communications Medicine. This is the first study to measure exhaled aerosols generated during exercise, to help inform the risk of airborne viral transmission of SARS-CoV-2 for gyms and indoor physical training.

Inhalation of infectious aerosol is considered to be the main route of SARS-CoV-2 transmission. In this study, researchers performed a series of experiments to measure the size and concentration of exhaled particles (up to 20µm diameter) which are generated in our respiratory tracts and breathed out, during vigorous and high-intensity exercise.

Using a cardiopulmonary exercise test, 25 healthy participants (13 male, 12 female) with a range of athletic abilities were recruited to undertake four different activities (breathing at rest, speaking at normal conversational volume, vigorous exercise and high-intensity exercise) on a cycle ergometer. Airflow and particles emitted were measured by particle counter. Experiments were carried out in an orthopaedic operating theatre — an environment with ‘zero aerosol background’, letting the researchers to unambiguously identify the aerosols generated by the participants.

The results showed that the size of airborne particles emitted during vigorous exercise was consistent with those emitted while breathing at rest. However, the rate of aerosol mass exhaled during vigorous exercise was found to be similar to speaking at a conversational volume.

Jonathan Reid, scientific lead on the paper, said: “COVID has profoundly impacted sports and exercise, and this study provides a comprehensive analysis of the mass emission rates of aerosol that can potentially carry infectious virus produced from an individual during exercise. Our research has shown that the likely amount of virus that someone can exhale in small aerosol particles when exercising is comparable to when someone speaks at a conversational volume.  The most effective way to reduce risk is to ensure spaces are appropriately ventilated to reduce the risk of airborne transmission.”

Source: University of Bristol

Categories : COVIDTags :

Kids are a Significant Source of COVID Spread in Households

On By ModernMedia

COVID spreads extensively in households, with children being a significant source of that spread. These are the findings from an antibody surveillance study published in CMAJ Open, which also shows that about 50% of household members were infected from the first-infected individual during the study period.

Although kids were less likely to spread the virus compared to adults, children and adults were equally likely to become infected from the first-infected individual.

The antibody surveillance study included 695 participants from 180 households in the Canadian city of Ottawa in Ontario, between September 2020 and March 2021. Included households had at least one member having had a confirmed COVID infection and at least one child within their household.

“Our study was conducted when we were dealing with a less transmissible virus and pandemic restrictions were strongly in place, and we still had a 50% transmission rate within households. Flash forward to where we are today with an extremely transmissible variant of COVID and the majority of pandemic restrictions lifted; it’s safe to say transmission rates will be higher even though we have a high vaccination rate amongst those who are eligible,” said Dr Maala Bhatt, the study’s lead author. 

“I know many want to ‘live with COVID’ and abandon the layers of protection that were previously mandated, but it’s important to be aware of the high transmissibility of this virus in closed, indoor settings, such as schools,” she cautioned.  “Our most vulnerable and our youngest children who are not yet able to be vaccinated are still at risk for COVID infection.”

In the Canadian province of Eastern Ontario, where the study was done, COVID is on the rise once again. Three-quarters of all children admitted to CHEO with COVID have come during the Omicron wave. Since the beginning of January this year a third of the roughly 4900 monthly visits to the Emergency Department were for COVID-related symptoms.

The study hypothesised that children would act as “an even greater source of spread within households with the emergence of more infectious variants.” Children also have “considerable potential to spread” in settings such as school and daycare, where they congregate indoors for long periods, especially now when masking is not required in many jurisdictions.

“While we’re lucky hospitals aren’t currently overloaded, emergency departments are and positivity rates are on the rise, even amongst children,” said Dr Bhatt, paediatric emergency physician and Director of Emergency Medicine Research at CHEO and an Investigator at the CHEO Research Institute.

“We continue to learn more about COVID and its potential long-term health impacts, and we still aren’t clear about how long immunity lasts; these are all things researchers continue to study.”

Source: University of Ottawa

Categories : COVID HospitalsTags :

Little COVID Viral Contamination Risk in Hospital Rooms

On By ModernMedia
Source: Martha Dominguez de Gouveia on Unsplash

A study found that hospital rooms where COVID patients were treated had little to no active virus contaminations on surfaces. The finding, published in Clinical Infectious Diseases, concluded that contaminated surfaces in the hospital environment are unlikely to be a source of indirect transmission of the virus, contrary to earlier views.

“Early on in the pandemic, there were studies that found that SARS-CoV-2 could be detected on surfaces for many days,” said the study’s senior author, Professor Deverick Anderson. “But this doesn’t mean the virus is viable. We found there is almost no live, infectious virus on the surfaces we tested.”

The researchers tested a variety of surfaces in the hospital rooms of 20 COVID patients at Duke University Hospital over several days of hospitalisation, including on days 1, 3, 6, 10 and 14.

Samples were collected from the patients’ bedrail, sink, medical prep area, room computer and exit door handle. A final sample was collected at the nursing station computer outside the patient room.

PCR testing found that 19 of 347 samples gathered were positive for the virus, including nine from bedrails, four from sinks, four from room computers, one from the medical prep area and one from the exit door handle. All nursing station computer samples were negative.

Of the 19 positive samples, most (16) were from the first or third day of hospitalisation.

All 19 positive samples were screened for infectious virus via cell culture with only one sample, obtained on day three from the bedrails of a symptomatic patient with diarrhoea and a fever, demonstrating the potential to be infectious.

“While hospital rooms are routinely cleaned, we know that there is no such thing as a sterile environment,” Prof Anderson said. “The question is whether small amounts of viral particles detected on surfaces are capable of causing infections. Our study shows that this is not a high-risk mode of transmission.”

Prof Anderson said the findings reinforce the understanding that SARS-CoV-2 primarily spreads through person-to-person encounters via respiratory droplets in the air. He noted that people should concentrate on known anti-infection strategies such as masking and socially distancing to mitigate exposures to airborne particles.

Source: Duke University

Categories : COVIDTags :

A Smaller Fourth Wave Predicted for South Africa as Flu Cases Spike

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A fourth wave of infections is likely for South Africa but its impact probably won’t be as severe as during earlier surges, as shown by new modelling, according to BusinessTech.

Factoring in sero-prevalence surveys and other data, it appears that an estimated 60% to 70% of the population has already contracted COVID, which along with vaccinations will provide protection from severe disease, the South African COVID-19 Modelling Consortium said in an online presentation on Wednesday.

Even in its worst-case scenario, deaths and hospitalisations during a fourth wave were projected to be substantially lower than during previous surges.

Though current caseload for the country is “incredibly low”, it is still “very hard to commit to say South Africa is over the worst” of the COVID pandemic, said Harry Moultrie, a senior epidemiologist at the National Institute for Communicable Diseases, which coordinated the modelling.

“It’s going to be a bumpy ride,” he said. “We don’t know where this virus is going to take us. We will still be seeing hospital admissions and deaths related to Covid for years to come.”

South Africa;s seven-day rolling average of new infections has fallen below 300, much reduced from a third-wave peak which hit nearly 20 000 in July.

To date, South Africa has had 2.93 million confirmed cases of COVID, with 89 504 deaths, although excess death numbers indicate the true toll may be much higher. About 34% of the nation’s 39.8 million adults have been fully vaccinated.

While some countries in the northern hemisphere such as Germany are seeing severe fourth and even fifth waves of infection driven by the spread of the delta variant, that’s not a good indicator South Africa will follow a similar path because the strain has already spread widely in the country, explained Gesine Meyer-Rath, a member of the modelling consortium.
“We have paid in a way with high deaths and a lot of destruction” during previous waves, Meyer-Rath said. “We don’t think we will have a super-fast case increase again” unless a highly transmissible new variant emerges, she said.

While the outlook for the fourth wave is brighter, the past few weeks has seen a sharp rise of influenza cases, the National Institute for Communicable Diseases (NICD) reported.

A high number of cases had been seen from the beginning of the month, including influenza-like illness and pneumonia hospitalised cases at surveillance sentinel sites.

The NICD added that there had been clusters of influenza cases reported in schools and workplaces.

The NICD’s Cheryl Cohen said: “The increase in influenza this summer, which is not the typical time for the influenza season in South Africa, is likely the result of the relaxation of non-pharmaceutical interventions to control COVID combined with other factors such as reduced immunity because flu has not circulated since 2020 and 2021.”

Sources: Eyewitness News; BusinessTech

Categories : COVIDTags :

Automated Messaging System Saved Lives in Early Pandemic

On By ModernMedia
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During the early days of the COVID pandemic, an automated text messaging system saved two lives a week, and, overall, the patients who enrolled in that system had a 68% lower mortality rate than those not on it.

These insights about Penn Medicine’s COVID Watch – a system designed to monitor COVID outpatients using automated texts and then escalate those with concerning conditions to a small team of health care providers – were published in the Annals of Internal Medicine.

“At the beginning of the pandemic, we instinctually thought patients needed extra support at home, even if they weren’t sick enough or ill yet. And if they were to get very sick, we wanted to help them get to the emergency department earlier, so COVID Watch was our solution,” said a co-primary investigator of the study, Krisda Chaiyachati, MD, the medical director of Penn Medicine OnDemand and an assistant professor of Medicine. “Our evaluation found that a small team of five or six nurses staffing the program during some of the most hectic days of the pandemic directly saved a life every three to four days.”

COVID Watch was rapidly developed and designed to help patients with the virus recover safely at home and keep hospital capacity available. The system uses algorithmically guided text message conversations with patients to assess their conditions. It sent out twice-daily routine questions to patients, such as “How are you feeling compared to 12 hours ago?” and “Is it harder than usual for you to breathe?” If a patient indicated a worsening condition, follow-up questions were asked and they were elevated to the human members of a centralised team – headed by co-author Nancy Mannion, DNP, COVID Watch’s nurse manager – who would call to check in and recommend hospitalisation, if needed.

Since the start of COVID Watch, nearly 20 000 patients have been enrolled in it.

“We did an early analysis of the system and determined that we could safely monitor more than 1,000 patients simultaneously, 24/7, with a small, well-trained team of registered nurses,” said Anna Morgan, MD, COVID Watch’s medical director and an assistant professor of Internal Medicine. “On top of that, those same nurses could often also take care of other COVID-related tasks such as helping patients arrange COVID testing and discussing their results, which is important during surges.”

To further assess COVID Watch’s effect on patients, researchers analysed data from every adult who received outpatient care from Penn Medicine, starting the day COVID Watch launched until Nov. 30, 2020. 
Only three out of 3448 patients in COVID Watch died within 30 days of their enrollment, compared to 12 of the 4337 otherwise equivalent patients outside of the program: a three times higher mortality rate. At 60 days after enrollment, five people within COVID Watch died compared to 16 not using the system.

This amounted to a 68 percent reduction mortality risk with COVID Watch. Additionally, COVID Watch was credited with saving 1.8 lives per 1000 patients at 30 days, and 2.5 per 1000 at 60 days.

The study’s lead author and co-primary investigator, M. Kit Delgado, MD, an assistant professor of Emergency Medicine and Epidemiology, believes that the benefits seen by COVID Watch patients could be explained by: Increased access to and use of telemedicine, and more frequent and earlier trips to the hospital – an average of two days earlier for COVID Watch patients – when symptoms worsened.

Importantly, the study found that COVID Watch was equally accessible and effective for everyone.

“We saw a higher proportion of higher-risk patients and also low-income and Black patients enrolled in COVID Watch, but the fact that we measured a significant benefit associated with enrollment in the program is a good indicator that there truly is a treatment benefit for everyone,” Prof Delgado said. “It’s crucial that we found all major racial and ethnic groups benefited because non-white and low-income communities have had disproportionately higher infection rates, lower access to care, and higher death rates. This implies that this model of care could have reduced disparities in COVID outcomes if it was scaled up more broadly to these communities.”

The COVID Watch team plans to see if the approach, which had originally been built off a system for keeping tabs on chronic obstructive pulmonary disease (COPD) patients, can be applied to helping people with other conditions manage their health at home. They see the system as a lasting technology that will play an important part in future care.

Source: Penn Medicine

Categories : COVIDTags :

Mask-wearing Protects Wearers Too

On By ModernMedia
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People who adhered to masking outside of the home, but were more exposed to infection due to their circumstances, still had “significantly” lower COVID infection rates, according to research published in BMJ Open.

Although it has been widely asserted that face coverings serve to protect others, rather than the wearer, this large-scale study established a clear link between wearing a face covering outside the home and infection.

The Oxford-led study links individuals’ and households’ ability to follow non-pharmaceutical interventions (NPIs) often known as COVID behavioural interventions, using the largest and most representative dataset to date in the UK, including people from different ethnic and age groups.

Using the COVID Infection Study (CIS), study participants were asked to complete a short questionnaire, as well as taking regular COVID tests. Respondents were asked to share how often they worked outside the home, how easy it was to keep social distance in their workplace, whether they took public transport and whether they had direct contact with others on a day-to-day basis.

According to the study, “Wearing a face covering outside was a significant predictor of a lower chance of infection before mid-December 2020 in the UK, when a stricter second lockdown was implemented.”

There was a higher rate of infections among those who lacked autonomy to follow COVID behavioural measures and did not comply with masking.

Author Professor Melinda Mills said, “Lack  of  compliance  to  COVID behavioural measures  has  often been  positioned  as  an  attitude  or  choice. Yet there are large groups of people who, due to their household or employment circumstances, cannot follow measures to work from home, engage in physical distancing at the workplace or avoid public transportation. This, in turn, means that they have a higher exposure to becoming infected.

“The inability for some groups of people to follow behavioural interventions exacerbates existing health inequalities and we showed that face coverings are one measure that can mitigate this unequal exposure.”

The team found, “The  level  of  autonomy  to  adhere  to  behavioural interventions does not  predict  COVID infection  alone,  but  rather the risk of infection is diminished when individuals wear face  covering/masks.”

The study concluded that masking reduces the effects of unequal COVID exposure.
Professor Mills added, “Using a very large individual and household sample and COVID swab tests, we showed that the inability for certain groups such as women in large households or those working in occupations where it is hard to maintain physical distancing were protected from infection during key periods in 2020 in the UK”.

Source: Oxford University

Categories : COVIDTags :

Kenya’s Waves Driven by Socio-economic Differences and Variants

On By ModernMedia
Phot by Martin Sanchez on Unsplash

By combining COVID surveillance data with population mobility data from smartphones, infectious disease modellers have explained the evolution of the first three COVID waves to hit Kenya. 

Sequential waves of transmission through different socio-economic groups, followed by infection boosted by the introduction of new variants.

In order to forecast future outbreaks, the team had to develop a model to explain current waves. The work brought together COVID antibody survey data, PCR case data, genomic variant data and Google mobility data, seeking to find an explanation to the waves of COVID in Kenya. The aim was to then provide policy-based forecasts on future waves in the country based on the model findings.

Lower socio-economic groups have been identified as vulnerable to SARS-CoV-2 in the global South due to living in densely populated informal settlements, with reduced access to sanitation, and relying on daily mobility for informal employment. In contrast, those from higher socio-economic groups with job security can work from home, physically distance and readily access water and sanitation, thereby decreasing transmission.
The modelling results show that differences in mobility and contact rates between high and low socio-economic groups within Kenya explain the differences between the first and second waves. In the initial phase of the epidemic (from March 2020), individuals in high socio-economic groups could reduce their mobility and contact rates, but individuals in lower socio-economic groups could not. This resulted in transmission among individuals in lower socio-economic groups that was observed as the first wave in urban centres. As these individuals recovered from infection and became immune, at least temporarily, the first wave ended.

By the onset of the second wave (from October 2020), individuals in high socio-economic groups had increased their contact rates and mobility. This led to transmission among individuals in the high socio-economic groups, and also involved rural as well as urban areas. The second wave then appeared to end as individuals cleared the virus and became immune, at least for the time being. However, the advent of the more infectious Beta and Alpha variants resulted in a third wave among both high and low socio-economic groups (from March 2021).

 In many other African countries, there have been multiple waves that are not fully explained by timing of restrictions, and as they have similar urban socio-economic groupings, the researchers speculate that these explanations may have wider applicability. Understanding the causation of such multiple waves is critical for forecasting hospitalisation demand and the likely effectiveness of interventions including vaccination strategy.

Dr Samuel Brand from the University of Warwick said: “This is one of the first studies to consider detailed predictions of the dynamics of COVID across multiple waves in tropical sub-Saharan Africa. We believe this sets a new standard for the type of public health modelling work that can be conducted in real-time in developing countries.”

Dr John Ojal of KEMRI-Wellcome Trust Research Programme said: “There are highly detailed modelling studies of this nature in High Income Countries, but there have been none previously in tropical sub-Saharan Africa.”

The study has been published in the journal Science.

Source: University of Warwick