Strategies combining self-isolation, moderate physical distancing and shielding likely most effective COVID-19 response

African countries can enact COVID-19 response strategies that reduce economic damage yet save many lives while also reducing health service pressure, suggests a new preliminary study by the London School of Hygiene & Tropical Medicine (LSHTM).

The research modelled the impact of different intervention strategies on severe cases and mortality in Niger, Nigeria, and Mauritius, countries chosen for analysis because they have the youngest, median-age and oldest populations in Africa.

A strategy combining self-isolation of sick people, moderate physical distancing and ‘shielding’ high-risk individuals in green zones was shown to be particularly promising, potentially reducing deaths in Nigeria from 605,000 (no intervention) to 285,000 over the next year.

The team say that lockdowns of two months’ duration, where socio-economically feasible, could complement such a strategy by delaying the epidemic by about three months, gaining time for planning and resource mobilisation.

COVID-19 epidemics are gathering pace across Africa. Many countries are responding by instituting Europe-style lockdowns, but there is doubt as to how sustainable and effective these can be given their fragile economies.

At the same time, countries are also trying to ramp up hospitalisation capacity, but available data suggests a nearly impossible mountain to climb, with projections of massive shortfalls in critical care beds, personal protection equipment (PPE) and ventilators.

The work was conducted by members of LSHTM’s Centre for the Mathematical Modelling of Infectious Diseases – led by Kevin Zandvoort and Christopher Jarvis.

Research team member Francesco Checchi said: “From high levels of poverty and armed conflict, to resource-constrained health services and disease burden, the odds are stacked against many African countries when it comes to COVID-19. Coupled with insufficient water and sanitation, and overcrowded cities, the health and economic toll of coronavirus may considerably exceed that of China, Europe and North America.”

The teams used methods similar to those that have projected the epidemic in the UK and elsewhere, but adapted some of the key parameters to better reflect what might happen in Africa. These include higher disease severity at younger ages and higher case-fatality.

They examined three specific interventions; self-isolation of symptomatic cases, general population physical distancing (strengthened handwashing, behaviour change, reducing the number of public gatherings, but short of shutting down any economic activities), and ‘shielding’ of high-risk individuals – where elderly people and people with co-morbidities are supported to live dignifiedly and safely, but separately from low-risk people.

They explored the effect of different strategies on severe, critical cases and deaths, and compared their impact against an unmitigated epidemic in the first 12 months after introduction of the first cases.

In relative terms, the results did not vary hugely. All three countries may experience very dramatic epidemic peaks. For example, in the absence of any control Nigeria, the most populous country in Africa, might require a peak of 200,000 intensive care beds. All interventions significantly reduced the expected number of total, severe, and critical cases.

Reducing physical distancing by 50% was estimated to have the largest impact within the 12 months. However, this strategy may result in a further epidemic wave beyond the first year, and requires serious socio-economic restrictions. By contrast, more moderate distancing, coupled with shielding of vulnerable people, might preserve the viability of African economies while also mitigating the epidemic’s impact.

Francesco Checchi said: “Full lockdowns work in reducing disease transmission, but in Africa extreme social distancing is likely to be very damaging. Working from home is not possible for most Africans. Responses must strike a balance between saving lives from COVID-19 and averting massive disruptions to livelihoods, which in the end also translates into lives lost.

“Sadly, there are no easy answers to combat the effects of this new virus, especially for Africa where required resources are scarce. Although the death toll on the continent will sadly still be catastrophic, our work suggests a combination of physical distancing, shielding, and self-isolation of symptomatic cases could save many lives in Africa, and may be a reasonable strategy for African countries to consider.”

The authors suggest neighbourhood-level house swaps to create shielding ‘green zones’, where high-risk residents are physically isolated for an extended period. They stress however that shielding would likely work best if communities and civil society actors are empowered and supported to design and implement locally appropriate solutions. Contact within the shielded population also needs to be minimised as much as possible, especially when there is limited reduction in contact between the shielded and unshielded community.

Francesco Checchi said: “Shielding should reduce transmission within the high-risk groups that may account for most hospitalisation and mortality. However, these arrangements must be community-led, rather than coercive. Humanitarian and development actors have a role to play to support such coping strategies.”

The authors acknowledge limitations of their work, particularly the outstanding unknowns about how the virus will affect African populations: its transmissibility in overcrowded cities versus rural areas, its severity in people already affected by HIV, tuberculosis, undernutrition and other co-morbidities, and how fatal it will be in the absence of appropriate treatment.

**This work has not yet been peer reviewed**

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

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