Covid-19, the official name given by the World Health Organization to the coronavirus disease that’s been dominating headlines for several weeks, has been successful on many fronts.

But there are many ways, both scientifically and naturally, in which it can be defeated. We shall explain why this is so based on our experience as an infectious disease specialist and an epidemiologist.

First, let us look at why the virus that caused Covid-19 is so potent.

For a start, it emerged in winter, where the colder temperature and lower humidity improved its chances of survival in the environment.

It is transmitted by respiratory droplets. This ensures that human interactions (within 2m) would result in cross infections. Coupled with humans living and interacting closely in the winter months, propagation and survival of the virus was assured.

The virus first struck two months prior to Chinese New Year, priming itself for the largest human migration on the planet in late January, as many of China’s 1.4 billion people headed home. Where the humans went, the virus followed, rapidly disseminating.

This was thwarted partially by an unprecedented lock down on Jan 23 of China’s Wuhan where it originated. But many infected individuals are believed to have travelled out of the major transportation hub before that, allowing pockets of infection to spread all over China and the rest of the world.

The virus has been found in faeces. This invoked unfounded rumours of airborne transmission within buildings via the sewage piping.

The virus also survives well on surfaces. It exploits human nature’s failure to wash hands regularly. The hands have become the medium for transferring viruses from surfaces to the face.

Covid-19 further takes advantage of the psyche of Asians, who continue to work whilst sick, as it is expected of them. All these have propagated the virus.

OVERCOMING THE SUPREMACY OF THE VIRUS

But science and nature can and will ultimately defeat the virus.

Covid-19 is genetically coded by a single-stranded ribonucleic acid. Errors occur frequently in such a code, permitting constant, frequent mutation without a second authenticating strand.

In contrast, mammals have double stranded deoxyribonucleic genetic material in a more robust coding system which is less error-prone.

The easy genetic mutation of Covid-19 allows it to adapt to harsh conditions and to jump across species type (from bats or pangolins to humans). This was how the original strain transferred from an animal host to a human. 

But ultimately the same mutation would preferentially select for a milder virus, as mutation to a highly pathogenic virus would kill the host and itself. Mutation to a milder infection, on the other hand, allows it to propagate as infected workers continue to meet, greet and spread.

With time, only the milder strain remains. This natural attenuation of a pandemic virus was reported in influenza H1N1, with death rates falling yearly. This took between three and five years.

The same will happen to Covid-19, though how long that will take is still unclear.

What we know is that besides Covid-19, there are four other current strains of coronavirus that cause mild upper respiratory tract infections. These probably represented similar coronavirus epidemics that were introduced in the history of mankind in a similar fashion, but science, at its infancy, had no records of it.

What else can we expect in the evolution of Covid-19?

For one thing, it would be curtailed by the coming warmer months. In warm weather and high humidity, survival and transmissibility of the virus fall. That was what happened in 2003 with the Sars outbreak. The Sars epidemic ended in July 2003.

The surest way to beat Covid-19 is with a vaccine, which scientists are racing to develop. But even if the trials are proven effective, it would still be 18 months before they are available.

What else can control the epidemic?

Overall herd immunity is one. This happens when a large number of individuals recover from the virus and become immune to it. However, this would not be expected for some years. This is because for protective herd immunity to take effect, more than 60 per cent of the population must have had prior infection.

Experiments in vitro suggest drugs such as lopinavir with ritonavir (currently in use for treating human immunodeficiency virus, better known as HIV, or remdesivir (a drug that was in development for treating the Ebola virus and the Middle East respiratory syndrome) may help contain the virus. Trials are currently underway to demonstrate clinical efficacy.

But the role of treatment drugs in curbing Covid-19 may be limited, given that more than 80 per cent of those infected will recover fully without antiviral therapy.  

Ultimately, the virus’ greatest weakness is its need to spread to a new uninfected individual. This usually creates a bottle-neck in any epidemic. 

If an infected individual avoids contact, the virus would fail to infect, and the reproductive index would fall, leading eventually to the end of the epidemic. 

EXPLOITING THE WEAKNESS OF CORONAVIRUS

The Singapore Government has rolled out comprehensive measures to deal with the Covid-19 outbreak, based on plans it had developed in the wake of Sars.

But the execution of each preventive measure would be only as good as its weakest link. What is perhaps lacking is a united response from Singaporeans. It is time for us to rise and prove our mettle.

Masks are a rare commodity, and as the crisis prolongs, they are best reserved for healthcare workers as well as those who are ill. The same could be said of personal protective equipment (gowns and mask) as well as sanitisers.  

Individuals who are sick must remain at home. They must wear masks if they go and see a doctor. Employers must accept this new norm where medical leave is more liberal.

Those who are well should consider working from home if permitted. We can stop the virus by cutting off physical contact.

Of course isolation is demoralising. So we have to watch out for each other in the community, without physically coming in contact with one another. A kind word or gesture for our neighbours and friends can provide much comfort in times like this.

Singaporeans must rise to the occasion by reliving the spirit of our fore-fathers. We should ask not what the Government can do for us, but what we can do for our neighbours. Singapore, together as one, can overcome Covid-19.

ABOUT THE AUTHORS:

Leong Hoe Nam is an infectious-diseases physician in private practice and Lim Hong Huay is an epidemiologist and development paediatrician.