When planning this article in late January, the novel coronavirus outbreak was not yet a month old, confirmed cases had not yet reached 600 and deaths from the virus was only at 17. Small numbers of cases were found in USA, Thailand, Japan and Republic of Korea. By 26th February 2020, the virus has been given a name, COVID-19, has over 80,000 confirmed cases in almost 50 countries and has claimed 2753 lives.

This article presents scenarios put forward by epidemiologists about what possible outcomes there are for the progression of the virus.

Scenario 1: COVID-19 goes global, while fizzling out in China.

COVID-19 is going global. The likelihood of this increases when infected people are globally mobile and are not yet showing symptoms. Countries need to have their preparedness plans for a disease outbreak and containment interventions ready for local deployment. The health systems of some countries may not be able to cope. This will be especially the case where dense cities and slum housing make isolation and tracing people in previous contact with confirmed cases more difficult.

The global nature of the pandemic may not involve an outbreak that is constantly raging. Instead, it could circulate in independent, self-sustaining outbreaks in major urban centres, such as Sao Paulo, Kinshasa, Teheran or New York.

Due to measures of isolation and containment enforced within China, COVID-19 could burn out in China, but a pandemic could be declared outside of the country.

Scenario 2: A seasonal infection.

The virus may slow and become a seasonal illness that will claim lives annually. Every winter, the flu, also a seasonal coronavirus, is the cause of death of 650 000 people worldwide. In the 1989-90 flu season in the UK, 26 000 people died due to flu-related causes. In the USA during 2017-2018, seasonal flu infected 45 million, of 61 000 people died. Each winter, COVID-19 could spread in a similar way to the flu until most people are exposed to it and develop immunity – or die from it. This follows epidemiological modeling, such as the hypothetical John Hopkins coronavirus projection that sees a new coronavirus spread throughout the world, exacts a heavy death toll and then the pandemic slows down.

Scenario 3: Mutation and enhanced virulence.

COVID-19 could mutate to become more infectious and more lethal. This would lead to a steep rise in confirmed cases globally and possibly a higher mortality rate than the current 2.3 %.

Scenario 4: COVID-19 is blocked and fails to progress.

COVID-19 could die out because the transmission of the virus is blocked. This can be done via public health measures, such as quarantine and isolation, as worked in the prevention of SARS in 2003. Alternatively, it can be blocked through the availability of new therapies and immunization, neither of which currently exist.

Discussion

All four scenarios may not be mutually exclusive. It is possible to see that aspects of scenarios 1, 2 and 4 are emerging. New virus cases within China do seem to be slowing down. The World Health Organization (WHO) stated today that there are more new cases outside of China than there are within the country. If COVID-19 becomes a seasonal virus, could it be more lethal than influenza? It is possible that the symptoms may be more severe with COVID-19, until we are more used to the virus, but the mortality rate may settle to being around the same as seasonal influenza.

Could COVID-19 mutate to become more contagious and lethal? From genetic analysis of samples taken from individuals infected in China, it appears that the virus remains stable in humans, becoming neither more or less harmful.

Regarding public health measure such as isolation and quarantine, has it worked so far in China? The virus has still spread exponentially outside of China, as well as within. Nonetheless, without the quarantine of Hubei province, the outbreak outside of China may have come sooner and with greater numbers of those infected.

A vaccine will take up to 18 months from development, clinical testing, approval and deployment. This means that individual country’s public health measures need to take priority.

The next article in this series focuses on the potential economic impacts of COVID-19, with particular reference to the pharmaceutical and medical device supply chains.

By Mark Gibson, Health Communication Specialist, 26th February 2020.

References:

Deadly unknowns, New Scientist, 8th February 2020
MacKenzie D, What happens next? New Scientist, 8th February 2020
Time and again, The Economist, January 25th 2020
Yi M, COVID-19: More new virus cases outside China than in, ‘no time for complacency’, says UN health agency, UN News, 26th February 2020 [ https://news.un.org/en/story/2020/02/1058141 ]

COVID-19: possible outcomes