Response strategies for COVID-19 epidemics in African settings: a mathematical modelling study

Zandvoort, Kevin van; Jarvis, Christopher; Pearson, Carl A. B.; Davies, Nicholas G.; Russell, Timothy; Kucharski, Adam J.; Jit, Mark; Eggo, Rosalind M; Checchi, Francesco

doi:10.1101/2020.04.27.20081711

Cited by 58 publications

(75 citation statements)

References 39 publications

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“…This finding highlights the importance of shielding older adults to lower their risk of acquiring SARS-CoV-2 infections, while allowing children in their households to benefit from routine vaccination to lower their risk of acquiring vaccine-preventable infectious diseases. 30 Although the young age demographic in Africa might mitigate some of the COVID-19 disease burden, infection fatality rates in Africa could be substantially higher because of the prevalence of likely risk factors, including HIV, tuberculosis, and malnutrition, and poor access to antibiotics to reduce the risk of bacterial co-infections in some parts of Africa. In the event that infection fatality rates in Africa turn out to be higher than elsewhere, then the estimated benefit-risk ratio would be reduced.…”

Section: Discussionmentioning

confidence: 99%

Routine childhood immunisation during the COVID-19 pandemic in Africa: a benefit–risk analysis of health benefits versus excess risk of SARS-CoV-2 infection

Abbas

Procter

Zandvoort

et al. 2020

The Lancet Global Health

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311

287

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Background National immunisation programmes globally are at risk of suspension due to the severe health system constraints and physical distancing measures in place to mitigate the ongoing COVID-19 pandemic. We aimed to compare the health benefits of sustaining routine childhood immunisation in Africa with the risk of acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection through visiting routine vaccination service delivery points. Methods We considered a high-impact scenario and a low-impact scenario to approximate the child deaths that could be caused by immunisation coverage reductions during COVID-19 outbreaks. In the high-impact scenario, we used previously reported country-specific child mortality impact estimates of childhood immunisation for diphtheria, tetanus, pertussis, hepatitis B, Haemophilus influenzae type b, Streptococcus pneumoniae, rotavirus, measles, meningitis A, rubella, and yellow fever to approximate the future deaths averted before 5 years of age by routine childhood vaccination during a 6-month COVID-19 risk period without catch-up campaigns. In the low-impact scenario, we approximated the health benefits of sustaining routine childhood immunisation on only the child deaths averted from measles outbreaks during the COVID-19 risk period. We assumed that contact-reducing interventions flattened the outbreak curve during the COVID-19 risk period, that 60% of the population will have been infected by the end of that period, that children can be infected by either vaccinators or during transport, and that upon child infection the whole household will be infected. Country-specific household age structure estimates and age-dependent infection-fatality rates were applied to calculate the number of deaths attributable to the vaccination clinic visits. We present benefit-risk ratios for routine childhood immunisation, with 95% uncertainty intervals (UIs) from a probabilistic sensitivity analysis. Findings In the high-impact scenario, for every one excess COVID-19 death attributable to SARS-CoV-2 infections acquired during routine vaccination clinic visits, 84 (95% UI 14-267) deaths in children could be prevented by sustaining routine childhood immunisation in Africa. The benefit-risk ratio for the vaccinated children is 85 000 (4900-546 000), for their siblings (<20 years) is 75 000 (4400-483 000), for their parents or adult carers (aged 20-60 years) is 769 (148-2700), and for older adults (>60 years) is 96 (14-307). In the low-impact scenario that approximates the health benefits to only the child deaths averted from measles outbreaks, the benefit-risk ratio to the households of vaccinated children is 3 (0•5-10); if the risk to only the vaccinated children is considered, the benefitrisk ratio is 3000 (182-21 000). Interpretation The deaths prevented by sustaining routine childhood immunisation in Africa outweigh the excess risk of COVID-19 deaths associated with vaccination clinic visits, especially for the vaccinated children. Routine childhood immunisation should be su...

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Section: Discussionmentioning

confidence: 99%

Routine childhood immunisation during the COVID-19 pandemic in Africa: a benefit–risk analysis of health benefits versus excess risk of SARS-CoV-2 infection

Abbas

Procter

Zandvoort

et al. 2020

The Lancet Global Health

Self Cite

311

287

View full text Add to dashboard Cite

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“…It is important to emphasize that, despite challenges, innovations for reducing transmission in complex settings exist (e.g., [57,58]) and evaluation of their individual or combined potential is important. Such innovations go beyond the standard non-pharmaceutical interventions being modeled [59,60] for HMIC and LMIC settings and may warrant investments, such as in sustainable infrastructure and development projects, with longer term impacts. [61] Like all studies, ours is not without limitations.…”

Section: Discussionmentioning

confidence: 99%

Coordinated support for local action: A modeling study of strategies to facilitate behavior adoption in urban poor communities of Liberia for sustained COVID-19 suppression

Skrip

Fallah

Bedson

et al. 2020

Preprint

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Background: Long-term suppression of SARS-CoV-2 transmission will require context-specific strategies that recognize the heterogeneous capacity of communities to undertake public health recommendations, particularly due to limited access to food, sanitation facilities, and physical space required for self-quarantine or isolation. We highlight the epidemiological impact of barriers to adoption of public health recommendations by urban slum populations in low- and middle-income countries (LMICs) and the potential role of community-based initiatives to coordinate efforts that support cases and high-risk contacts. Methods: Daily case updates published by the National Public Health Institute of Liberia were used to inform a stratified stochastic compartmental model representing transmission of SARS-CoV-2 in two subpopulations (urban poor versus less socioeconomically vulnerable) of Montserrado County, Liberia. Differential transmission was considered at levels of the subpopulation, household versus community, and events (i.e., funerals). Adoption of home-isolation behavior was assumed to be related to the proportion of each subpopulation residing in housing units with multiple rooms, access to sanitation facilities, and access to basic goods like water and food. Percentage reductions in cumulative infection counts, cumulative counts of severe cases, and maximum daily infection counts for each subpopulation were evaluated across intervention scenarios that included symptom-triggered, community-driven efforts to support high-risk contacts and confirmed cases in self-isolation following the scheduled lifting of the state of emergency. Results: Modeled outbreaks for the status quo scenario differed between the two subpopulations, with increased overall infection burden but decreased numbers of severe cases in the urban poor subpopulation relative to the less socioeconomically vulnerable population after 180 days post-introduction into Liberia. With more proactive self-isolation by mildly symptomatic individuals after lifting of the public health emergency, median reductions in cumulative infections, severe cases, and maximum daily incidence were 7.6% (IQR: 2.2%-20.9%), 7.0% (2.0%-18.5%), and 9.9% (2.5%-31.4%) for cumulative infections, severe cases, and maximum daily incidence, respectively, across epidemiological curve simulations in the urban poor subpopulation and 16.8% (5.5%-29.3%), 15.0% (5.0%-26.4%), and 28.1% (IQR: 9.3%-47.8%) in the less socioeconomically vulnerable population. An increase in the maximum attainable percentage of behavior adoption by the urban slum subpopulation, with the provision of support to facilitate self-isolation or quarantine, was associated with median reductions in cumulative infections, severe cases, and maximum daily incidence were 19.2% (IQR: 10.1%-34.0%), 21.1% (IQR: 13.3%-34.2%), and 26.0% (IQR: 11.5%-48.9%), respectively, relative to the status quo scenario. Conclusions: Broadly supported post-lockdown recommendations that prioritize proactively monitoring symptoms, seeking testing and isolating at home by confirmed cases are limited by resource constraints in urban poor communities. Investing in community-based initiatives that determine needs and coordinate needs-based support for self-identified cases and their contacts could provide a more effective, longer-term strategy for suppressing transmission of COVID-19 in settings with prevalent distrust and socioeconomic vulnerabilities.

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“…In these settings, social-distancing is demonstrated to be an effective intervention, and even small changes are estimated to have large effects on outbreaks [24], in some cases determining whether or not already inadequate healthcare systems become overwhelmed [25]. Zandvoort et al show that similar measures to the ones we consider: self-isolation, physical distancing and "shielding" the vulnerable, may reduce mortality by 60%-75% in African cities [10]. Self-distancing proves to be an effective measure in our models as well; reducing contacts by 50% has the greatest effect across most outcomes of interest in any of the interventions we examined.…”

Section: Discussionmentioning

confidence: 99%

“…Building upon the approach used to model the impact of these interventions in African cities, our model includes a parameterization of the contacts each individual has per day [10]. We further elaborate upon this approach by making a more explicit representation of contacts and other parameters in the model.…”

Section: Introductionmentioning

confidence: 99%

Empowering the crowd: Feasible strategies for epidemic management in high-density informal settlements. The case of COVID-19 in Northwest Syria

Pascual‐García

Klein

Villers

et al. 2020

Preprint

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More than 1 billion people live in informal settlements worldwide, where precarious living conditions pose additional challenges to the management of a COVID-19 outbreak. Well-established measures, such as social distancing, testing, contact tracing, improved hygiene, and generalized use of personal protective equipment, are almost impossible to implement. We specifically investigated the impact of adapting these measures to informal settlements located in regions immersed in protracted conflicts, taking the Northwest region of Syria (NWS) as a case study. Such regions need to contend with the public health challenges resulting from violence, deterioration of health-systems, and political instability. We implemented a stochastic Susceptible-Exposed-Infectious-Recovered model to simulate the spread of the virus in high-density camps of Internally Displaced Persons, using a population structure representative of these camps. We chose parameters corresponding to a worst-case scenario where there is no healthcare available. We expanded on previous models to adapt feasible interventions to the living conditions in the camps, including moderate self-distancing, self-isolation of symptomatic individuals, and protection of the most vulnerable in "safety zones". All the interventions significantly reduce the probability of observing an outbreak and the death toll. Self-distancing brings the best results if contacts are reduced by 50%, with mortality reduced by up to 35%. A similar reduction in mortality can be achieved by providing 1 self-isolation tent per 200 individuals. Protecting the vulnerable in a safety zone has synergistic effects with previous interventions for the whole population, but is especially beneficial for the vulnerable population. Complementary measures, such as lockdown of the safety zone when a first case is detected in the camp, further reduce mortality and the probability of an outbreak. Our model predicts that a combination of all simulated interventions may reduce mortality by as much as 80%. The time until the number of symptomatic cases peaks is delayed by most of the interventions, in some cases by more than three months. The proportion of the population that recovers, near 70%, could help prevent future outbreaks. Our results highlight the potential of non-medical interventions to mitigate the effects of the pandemic. They demonstrate that interventions shown to be effective in other settings can be adapted to refugee camps and are most effective when implemented in tandem. Our modelization considers complementary measures to these interventions that can be implemented autonomously by these communities, such as buffer zones, daily health-checks, and carers for isolated individuals, quantifying their impact on the micro-dynamics of disease transmission. Similar measures may be applicable to controlling COVID-19 in other informal settlements, particularly Internally Displaced Persons camps in conflict regions, around the world.

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Response strategies for COVID-19 epidemics in African settings: a mathematical modelling study

Abstract: Background

Cited by 58 publications

References 39 publications

Routine childhood immunisation during the COVID-19 pandemic in Africa: a benefit–risk analysis of health benefits versus excess risk of SARS-CoV-2 infection

Routine childhood immunisation during the COVID-19 pandemic in Africa: a benefit–risk analysis of health benefits versus excess risk of SARS-CoV-2 infection

Coordinated support for local action: A modeling study of strategies to facilitate behavior adoption in urban poor communities of Liberia for sustained COVID-19 suppression

Empowering the crowd: Feasible strategies for epidemic management in high-density informal settlements. The case of COVID-19 in Northwest Syria

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