A return to tighter lockdown restrictions could be harder to enforce

New research by academics led by the University of Pretoria models three scenarios for the spread of Covid-19 in South Africa, combining previous models with new data.

The results paint a worrying picture for the rate of infection against the country’s ICU capacity, amid decreasing levels of compliance to lockdown regulations.

To curb the spread of Covid-19, many governments around the world have implemented tiered lockdowns with varying degrees of stringency. Lockdown levels are typically increased when the disease spreads and reduced when the disease abates.

South Africa’s approach to the Covid-19 pandemic is interesting, because as the number of infections grows exponentially towards peak, so government has been forced to reopen the economy, by relaxing lockdown laws.

The early, strict lockdown measures, proved to be successful from an epidemiological point of view, but at the cost of economic activity.

Government faced pressure from businesses and economists to open the economy to save livelihoods, jobs and businesses – while having to accept that this would lead to a rapid rise in the number of infections in the country.

The government is currently debating a plan to reintroduce hard lockdowns in the country’s hotspot areas, most notably Gauteng. This measure could be more difficult to enforce than the first time around, however.

Two scenarios

The researchers used their modelling to look at two different scenarios in the country – one which focuses on flattening the curve, and the other more closely aligned to the current strategy of balancing infections and economic losses.

In the first simulation, the researchers looked at a proper ‘flattening the curve’ model, where the number of cases in the country remain in control and below the ICU bed threshold.

Under this scenario, the lockdown starts early, and stays in effect for 308 days, with higher levels (level 4 and level 5) persisting to the end of the year, before gradually dropping to level 1 by March 2021.

Simulation results for the flattening the curve policy scenario. The top panel shows the active number of confirmed infectious cases along with the number of ICU beds imposed high limit (dashed line) over time and the bottom panel shows the lockdown level over time.

This scenario is not economically viable for South Africa, as extended periods of restriction on trade and movement would have obliterated an already severely damaged economy, and sacrificed the livelihoods of millions of South Africans in exchange for a more controlled pandemic.

In the second simulation, lockdown levels were adjusted to balance infections and economic losses.

This policy balances lives and livelihoods by delaying the start of lockdown by a week and reducing the total time in lockdown by 8 weeks. Furthermore, while in lockdown fewer days are spent in each level.

Here, the number of cases exceeds ICU bed capacity, but authorities would still be able to estimate how many beds would be needed and could plan interventions around that.

Simulation results for the balancing lives and livelihoods policy. The top panel shows the active number of confirmed infectious cases along with the number of ICU beds imposed high limit (dashed line) and the weighted cumulative economic impact (dotted line) over time and the bottom panel shows the lockdown level over time.

“If the economic impact of each level of lockdown can be quantified beforehand, temporary ICU facilities can be procured to the point where lockdown might be eased earlier to limit the cumulative economic impact while the ICU limit is still respected,” the researchers noted.

What happens when people stop complying?

While the two scenarios outlined above model the data in terms of infection vs capacity against the economic impact – the third scenario factors in compliance, which is a bit of a wildcard.

Compliance to lockdown regulations has seemingly waned over time in South Africa, the researchers said, and in their modelling never returns to prior levels, even if restrictions tighten in response to rising infections.

After the initial decrease, however, the level of compliance is set to increase every time the lockdown level is reduced – “this is because there are fewer regulations on lower levels, and the level of compliance to those regulations will likely be higher, initially”.

However, after the initial surge, compliance will again reduce in a linear fashion, they said.

Adding this compliance pattern to the economic balance scenario, the situation for infections vs capacity gets significantly worse.

Simulation results for the balancing lives and livelihoods policy with waning compliance to regulations. The top panel shows the active number of confirmed infectious cases along with the number of ICU beds imposed high limit (dashed line) and weighted cumulative economic impact (dotted line) over time and the bottom panel shows the lockdown level (blue) and compliance (orange) over time.

“After a couple of weeks in lockdown, the population starts to deviate from the rules and the effective number of contacts per person increases, which consequently increases the spread of the
virus.

“To try and curb this phenomenon the controller moves the lockdown level back to 5 as it applies feedback to try and balance the ICU bed imposed limit with the economic impact of the lockdown.

“After another period at level 5 the cumulative economic impact has however ballooned, while compliance remains relatively low. Left with large economic losses and a non-compliant population, the controller ramps down the lockdown level from 5 to 1 in a relatively short time,” they said.

While compliance levels do increase at each reduction of the lockdown level, this has little impact given the magnitude of the cumulative economic losses, the researchers said.

The researchers found that while the initial ‘flattening the curve’ approach to the pandemic could result in the ICU threshold being kept, the economic consequences proved to be too severe.

The ‘balancing lives and livelihoods’ policy allows for increased economic activity by reducing the lockdown level earlier – but at the cost of higher rates of infection.

However, in any model, levels of compliance need to be included as an “unmeasured disturbance”, the researchers noted.

Since the spread of the virus is ongoing and the peak number of active cases has not yet been reached, future work needs to be considered.

This includes looking at regional models versus the national picture as a whole – and the potential impact of a possible vaccine somewhere down the line.

You can view the full paper here.


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A return to tighter lockdown restrictions could be harder to enforce