The projected impact of mitigation and suppression strategies on the COVID-19 epidemic in Senegal: A modelling study

  1. Hayley A Thompson
  2. Aminata Mboup
  3. Badara Cisse
  4. Shevanthi Nayagam
  5. Oliver J Watson
  6. Charles Whittaker
  7. Patrick G T Walker
  8. Azra C Ghani
  9. Souleymane Mboup
  10. With the Imperial College COVID-19 Response Team

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Abstract

Background

Physical distancing measures that reduce social contacts have formed a key part of national COVID-19 containment and mitigation strategies. Many Sub-Saharan African nations are now facing increasing numbers of cases of COVID-19 and there is a need to understand what levels of measures may be required to successfully reduce transmission.

Methods

We collated epidemiological data along with information on key COVID-19 specific response policies and health system capacity estimates for services needed to treat COVID-19 patients in Senegal. We calibrated an age-structured SEIR model to these data to capture transmission dynamics accounting for demography, contact patterns, hospital capacity and disease severity. We simulated the impact of mitigation and suppression strategies focussed on reducing social contact rates.

Results

Senegal acted promptly to contain the spread of SARS-CoV-2 and as a result has reduced the reproduction number from 1.9 (95% CI 1.7-2.2) to 1.3 (95% CI 1.2-1.5), which has slowed but not fully interrupted transmission. We estimate that continued spread is likely to peak in October, and to overwhelm the healthcare system with an estimated 77,400 deaths (95% CI 55,270-100,700). Further reductions in contact rates to suppress transmission (R t <1) could significantly reduce this burden on healthcare services and improve overall health outcomes.

Conclusions

Our results demonstrate that Senegal has already significantly reduced transmission. Enhanced physical distancing measures and rapid scale up of hospital capacity is likely to be needed to reduce mortality and protect healthcare infrastructure from high levels of demand.

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    SciScore for 10.1101/2020.07.03.20144949: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: Thank you for sharing your code and data.

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    There are several limitations to the analyses presented here. Firstly, we rely on reported deaths to calibrate the model and estimate R0 and how it changes in response to control measures. Due to the low number of deaths, all scenarios presented here are highly uncertain and this needs to be borne in mind. In addition, the extent of under-reporting of deaths from COVID-19, and how it varies across the country, remains unclear. Here, we assume a 50% death ascertainment rate; whilst our results are sensitive to the extent of under-reporting assumed, they do not qualitatively change our conclusions surrounding healthcare capacity exceedance and the need for more stringent control measures. Given the small number of deaths to date, we only undertook this analysis at a national level; however it is clear from the geographical concentration of cases that there will likely be regional differences in the scale of individual outbreaks, as we have seen in other countries experiencing more advanced epidemics, and therefore further work will be need to understand regional trends and as such adapt policy to local needs. Additionally, we currently use Google mobility data to estimate the impact of emergency measures on contact patterns. While mobile phone coverage in Senegal is increasing annually, penetration throughout the population remains low. In 2018 only 34% of the population owned a smartphone with internet access compared to around 82% in the United Kingdom.36 Systematic biases in...

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    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
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    • No protocol registration statement was detected.

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  2. Version published to 10.1101/2020.07.03.20144949v1 on medRxiv