Understanding the Deadliness of the New Coronavirus: Challenges in Estimating Mortality Rates

As news about the new coronavirus spreads, one of the key questions on many people's minds is whether it is as deadly as SARS or whether we can expect a similar level of fatality. While it's too early to make a definitive statement, the new coronavirus shares some characteristics with SARS, particularly in causing pneumonia-like symptoms. However, the distribution of cases presents significant challenges in accurately estimating the mortality rate of this new epidemic.

Challenges in Estimating Mortality Rates of New Epidemics

As Jack Bridges so aptly pointed out, it's exceptionally difficult to provide a reliable mortality estimate during the early stages of a new epidemic. This difficulty arises due to the nature of the growth curves of both fatalities and reported cases. These curves are exponential, which can be easily manipulated by shifting the origin or scaling with a constant. For instance, an apparent low mortality rate could simply reflect a longer time lag between initial diagnosis and the final outcome.

Another critical factor is the unknown number of infections where patients recover without medical intervention and are not recorded at all. This oversight could either under-estimate or over-estimate the actual mortality rate, depending on the circumstances. Moreover, the early diagnosed cases were typically those who were already showing severe symptoms, meaning they were not representative of the general population. This sample bias can further skew the reported mortality rates.

Lastly, the reporting of recoveries is a significant challenge. Until systems are in place to report confirmed recoveries to central authorities, mortality rates may be artificially inflated. This can occur when hospitals prioritize beds for critically ill patients and refrain from reporting recoveries until they have no alternative. A requirement to report recoveries only became possible in mid-January, allowing for more accurate testing of patients.

Risk and Comparison with Previous Outbreaks

It's important to mention that the new coronavirus may present a different risk profile compared to SARS and MERS. SARS, which infected over 8,000 people in 2003, resulted in 774 deaths, giving it a mortality rate of approximately 9.6%. On the other hand, MERS, identified in 2012, has a higher mortality rate of around 34%, making it significantly more dangerous.

The preliminary data and early estimates of the new coronavirus' mortality rate need to be interpreted cautiously. The early reported numbers might be skewed by factors such as case severity and reporting biases. To accurately estimate the mortality rate, we need access to a more comprehensive dataset that includes symptomatic and asymptomatic infections, as well as comprehensive reporting of all cases and recoveries.

Conclusion

Understanding the deadliness of the new coronavirus is crucial for formulating public health policies and preparing healthcare systems. While the challenges in estimating the mortality rate are significant, ongoing research and data collection are essential. As more cases are identified and the virus's behavior becomes clearer, we can expect to have a better understanding of its true impact.

Key Points:

Exponential growth curves complicate mortality rate estimation. Under- and over-reporting of infections and recoveries impact accuracy. Initial cases often represent a non-representative sample of the population. Comparison with previous outbreaks (SARS, MERS) highlights the unique characteristics of this new coronavirus.

References

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Updated data and further resources can be found at the CDC and WHO websites.