COVID-19: why has WHO declared a global emergency now?

All significant epidemics become politicized. The decision to declare an emergency can be divided into two factors.

1. Medical Factors: 

This is an evolving epidemic of a novel infectious disease. We have explained the distinction between the disease and the epidemic. This disease is currently trending with a mortality around 2%. This has the potential to change in severity for better or worse and as such the current case fatality rate may overstate or understate the true severity of the disease. Past experience of similar epidemics makes it most likely that the mortality rate will reduce rather than increase with time.

The global severity will ultimately be determined by the evolution of the epidemic. The current public health measures  are aimed at slowing down both the rate of progression and ultimate size of the epidemic.

1. The lower the epidemic size (number of people infected) the lower the number of people who will become ill and the lower the total mortality.
   
   
2. The lower the absolute volume of circulating virus the lower the risk of viral mutation.
   
   
3. The lower the epidemic size the higher the likelihood of it dying out naturally. This may be influenced by environmental factors. For example, coronavirus infections often die out in Spring with an increase in warmer and more humid weather.
   
   
4. Slowing the evolution of the epidemic buys time in order to:

1. 1. develop tests to help us better understand the nature of the infection and the optimal control methods
   2. develop treatments to optimally manage the illness
   3. develop a vaccine which is ultimately one of the most effective methods of controlling epidemics of infectious disease.

2. Political Factors:

Poverty is the single most important factor in global health. Epidemics of infectious disease have greatest impact on the young, the old, the poor and the immunocompromised. The World Health Organization has a remit to act for the vulnerable members of all communities of the world and Global Health emergencies are really designed to ensure that funding, expertise and national cooperation can be targeted specifically at countries with less resources or poorly developed health systems. They were not designed for countries with large global economies.

Ultimately the WHO were looking at the potential severity of the disease but most importantly at the potential for a significant epidemic spreading beyond the initial cohorts in China especially into countries with less developed health systems. The evidence of case to case transmission outside China suggested a potential escalation and many observers expected the emergency to be declared earlier. Certainly there will have been political factors in the decision. The Director General of WHO praised China for their “unprecedented response” and the extraordinary public health measures undertaken.

In summary, the declaration of the global emergency now does not indicate a worsening of the immediate situation in China or Hong Kong.

To learn more about the differentiation between a disease and an epidemic, click here.