Covid-19 Chronicles #13: Don’t let science be trumped by self-interest

We were doing so well.

Daily life was resuming. Surviving businesses were getting a chance to pick up.

Community activities were resuming and holidays and weddings were celebrated—albeit at a smaller scale under some level of mask wearing and physical distancing.

Yet, even with a relaxed adherence to precautions for the most part (sometimes bafflingly), Covid-19 in Malaysia seemed under control.

Ultimately, this may be due to a combination of factors. These factors are;

1) that the movement control order (MCO) was lifted after local transmissions were sufficiently low, and since the curve was flattened, the ability of Malaysia’s health systems to test, isolate, and manage infected people improved significantly and thus, we are able to buffer mild spikes from imported cases such as the Sivagangga cluster, or breaches in adherence to standard precautions on a community level,

2) some studies suggest the Covid-19 virus strains circulating locally are less virulent, albeit still highly contagious (thus many of us may have been asymptomatically infected and recovered without ever knowing it), and

3) other studies hypothesize that high levels of BCG vaccination in countries like Malaysia or immunity to dengue may be conferring some protection against the virus.

Although none of the explanations are conclusive, with talk of vaccines to protect populations at risk becoming more concrete, there seemed to be a vision of light at the end of this odd tunnel that is 2020.

That said, two wild cards remained that could be game changers; one is the re-opening of international borders and the second is large mass gatherings, particularly those that mix previously separated groups of people. Both open up a number of possibilities that could shift our current Covid-19 trajectory.

When trying to project the trajectory of infectious diseases, a key parameter used is the R0, which for Malaysia pre-MCO may have been between two and four. This number is interpreted as the average number of people an infected person spreads the virus to in an unvaccinated population during the course of their infectious period. This infectious period usually coincides with symptoms like coughing and fever, although perplexingly, Covid-19 may be spread even two or three days before symptoms appear.

To interrupt transmission, the aim is to bring down the R0 below 1, because that means on average one person will not infect another person. Usually projections or models of infectious disease assume that the population is homogeneous—meaning their characteristics and interactions within the population occur in a similar pattern.

This assumption has worked reasonably for projecting and managing some infectious diseases, but recent studies are now arguing that it may not be as useful for Covid-19.

This is because Covid-19 transmission appears to be highly sensitive to population heterogeneity. The virus has a very high over-dispersion rate, whereby a majority of the transmissions are driven by a small fraction of infectious people. These people may not necessarily be harbouring a more infectious strain, but their role in society and activities may allow them to meet and interact closely with more people than the average person. Such transmission events - where a small number of infectious people spark a large cluster of newly infected persons - are called super-spreader events.

One reason why the MCO was able to interrupt sustained spread of Covid-19, is because it reduced the risk of super spreaders. In that critical period while the Covid-19 numbers were climbing and the health systems were still building resources, the MCO disrupted existing social networks, significantly reduced mixing of people, and prevented potential super spreader clusters that may have overwhelmed the hospitals.

But even now, as we are in the recovery MCO, gatherings that enable previously separated groups of people to congregate (for example, interstate travellers convening to vote, attend campaigns, or register for university), create ripe conditions for super spreading to occur.

While super-spreader events do not necessarily result in a significant shift in Malaysia’s Covid-19 trajectory, a sufficient number coupled with significant lax in precautions, such as not adhering to physical distancing or quarantine, certainly could.

We had very little time to adapt to the threat of Covid-19 in the earlier wave, and yet with little preparedness, universities somehow shifted to remote teaching and learning with various degrees of success.

Now we have had time to improve and learn from the experience, to devise better ways to continue remote teaching if necessary. Instead, when universities were instructed to plan for the new semester in October, it did not come with contingencies if cases began to rise again. Everyone was instructed to assume that Covid-19 remained under control.

However, the hundreds of daily new cases we are again seeing clearly shows that controlling Covid-19 is a tenuous act, one that must be at the forefront of our plans and not an afterthought..

While the science behind Covid-19 is still developing, we must use the science we have now to urgently develop contingency plans. Clearly, mass gatherings for any reason are risks we cannot afford to take. With other activities that require mass participation looming ahead, we must find ways to conduct these responsibly, without physical congregation, to reduce the risk of resurgence.

In the meantime, we can try to do some damage control as individuals by taking precautions more seriously, reducing unnecessary mobility, and imposing self-quarantine if we think we may be at risk of having Covid-19. If we can collectively do that, we may still be able to avert another disruptive lockdown.

This is a critical time. We may still return to the path of controlling Covid-19 and head towards the light at the end of the tunnel.

But we must all make decisions better aligned to science rather than self-interest to get us through the end.