In managing a likely ‘second wave’, physical distancing, mask-wearing and hand-washing remain our most important weapons
Is a second wave inevitable in South Africa?
Many Western European countries are experiencing a resurgence, or “second wave”, of Covid-19 infections. Caution needs to be exercised in extrapolating from the resurgence in Europe and applying conclusions to South Africa.
Knowledge of transmission and exposure patterns in our own setting must inform a calibrated and transparent response, not least because its most important component is willing and voluntary compliance throughout the populace.
Rationale for Europe’s new lockdowns The UK, France and Spain are introducing a new round of curfews and considering lockdowns. This might be effective in countries able to support a lockdown from a societal and economic perspective. These measures are also underpinned by low levels of immunity in the general populations.
Should this apply to us?
We believe our context is different. Countries have two choices to get transmission under control.
They can try mitigation to reduce transmission, achieved by isolating cases and quarantining close contacts (requiring a robust test-and-trace capability); adherence to distancing, masks and hand hygiene; and protecting people who will have the worst outcome from being infected.
Suppression or lockdown aims to reverse epidemic growth, reducing case numbers by social or physical distancing the entire population indefinitely.
It is evident that while our hard lockdown slowed transmission and that some hospitals were able to prepare for the expected increase in admissions, this was uneven and did not manage to stop transmission.
South Africa, despite having one of the earliest and harshest lockdowns for a protracted time period, did not achieve suppression, nor was it likely to.
This is due to the lack of an integrated approach to the outbreak, from initiating community screening to tracking Covid-19 disease outcomes; and the inability to scale up community testing in time, with concomitant long turnaround times and inadequate contact tracing.
The international experience is illuminating. Except for a few island nations, failure to achieve viral control was the outcome for most countries, whatever measures were applied. The World Health Organisation concurred that a lockdown alone would not eliminate or permanently control the spread of the virus unless coupled with an efficient system of testing and high rates of tracing their contacts.
Enforcement of lockdown measures locally deepened mistrust of the authorities and may have contributed to poor compliance with mitigation measures across society. Alongside inadequate testing and tracking infrastructure, this resulted in only a temporary reduction in community transmission over the first four to six weeks of lockdown.
Reproductive rate of South African epidemic under various stages of lockdown
The persistence of transmission is evident through an analysis of the effective reproduction rate (Re) of SARS-CoV-2 in South Africa. Re determines whether the number of cases in the population will go up (when Re >1) or down (Re <1). During level 5 lockdown Re ranged from around 1.5 to 2, indicating ongoing community transmission.
Re only declined substantially after the July surge, following large-scale exposure in various Western Cape and Gauteng communities, thereby reducing the number of people susceptible to infection. At the time of level 3, up to 40% of the population in certain regions demonstrated Covid-19 antibodies.
Did lockdown or mass exposure do the trick?
Data suggest that the proposition that the highly restrictive lockdown prevented community transmission and contributed to the first wave waning, is inaccurate.
Infection rates only started declining and Re trended downward to approximately 1 from July onwards, as restrictions eased. The proposition that the interruption in the transmission chain due to an increasing proportion of the population being gradually infected and developing partial immunity is supported by surveys across Western Cape districts, where 40% of women attending antenatal clinics and people living with HIV had evidence of infection, suggesting a massive “covert” wave of infection.
Practices such as maximum taxi occupancy and resumption of attendance at places of worship, incrementally allowed during relaxation of the lockdown, undoubtedly increased transmission risk.
Partial implementation of non-pharmaceutical interventions (NPIs) mitigated the full potential consequences of these actions. NPIs include hand washing, physical distancing and wearing a mask in public. Consistent messaging around this was the workhorse of our public health response and has had some effect.
The massive surge in infections during winter may have interrupted the transmission chain by inducing some immunity in a high percentage of the population, particularly in densely populated areas. However, the population percentage infected is likely far less than estimated (60%-70%) to enable sustainability of low infection rates (Rt<1.) — so-called herd immunity — due mainly to increasing complacency around the adoption of NPIs, making a resurgence likely in the short term. Uncertainty regarding the persistence of immunity following infection makes realistic projections difficult. Emerging evidence is still insufficient to confidently estimate the longevity of immunity.
Lessons from other countries
One similarity between the epidemics in South Africa and in Europe has been a reduction in cases correlated with warmer seasons, with changing human behaviour probably the deciding factor. Spending more time outdoors and the ability to better ventilate spaces are critical.
However, one lesson is important: the opening up of European societies during summer was likely coupled with lower adherence to NPIs, resulting in a resurgence of infections. Our adherence to these interventions must continue unabated and is absolutely critical if we are to be spared the worst of a resurgence.
Different testing rates and strategies in many European countries make it impossible for head-to-head comparison of the scale of the resurgence rela
tive to the first waves.
Similarly, we cannot make meaningful head-to-head comparisons between (and even within) countries in respect of the number of infections or death rates that may result here. This makes gaining any insights into what could happen in South Africa inordinately difficult.
Resurgence likely, but our response should be different
A resurgence in South Africa is certain, but likely to be different to Europe’s. Of particular importance is the fact that a resurgence in settings where there was a high rate of infection during the first wave is likely to be of a lower magnitude now. Conversely, communities with low rates of infection in the first wave may be disproportionately affected during the second wave.
Seroprevalence surveys to characterise the proportion of communities infected during the first wave will be a vital indicator of where resurgences might be concentrated.
That may mean that provinces with a lower rate of infection in the first wave may be settings for higher rates of infection and mortality. Strategies to meet this expectation must be urgently put into action, from active adherence to NPIs and building robust test-and-trace infrastructure to strengthening healthcare infrastructure.
We can be certain that the type of hard lockdown imposed in March will only inflict further, perhaps fatal, damage to an economy that was on the ropes and rendered moribund by the hard lockdown. It will also significantly undermine any chance of an economic recovery, without achieving any meaningful net health impact.
The only instrument in our current toolkit to blunt and minimise the consequences of a resurgence is to actively motivate society to continue adhering to NPIs.
This is the most important work of the political classes: to act in support of and not attempt to second-guess the scientific and health system imperatives. Even if NPIs are not always implementable at scale, they contribute massively to the control of the transmission rate and would assist in avoiding overwhelming the beleaguered healthcare system.
There can be no more important activity for the government and its social partners at this time.
Except for a few island nations, failure to achieve viral control was the outcome for most countries, whatever measures were applied.