Why the most comprehensive COVID-19 study yet suggests a mortality rate of 0.66%

The most comprehensive study to date on the outcomes of COVID-19 has some interesting insights. Compiled by researchers from Imperial College, London, the numbers suggest that the mortality rate is as low as 0.66%. This may sound like an insignificant figure, but the study also showed profound differences by age group. Most notably, spikes were seen in the 50-59 age group, with rates of hospitalization and death suddenly going up.   [caption id=“attachment_8211431” align=“alignleft” width=“380”]  Representational image. Image by 贺 朱 from Pixabay.[/caption] There were 70,117 confirmed cases from mainland China, along with 689 confirmed cases who were evacuated from Wuhan to their home countries, involved in the study.   The study confirms previously held views about mortality going up with age, but since the dataset is the largest so far, policymakers can use it to refine interventions. Since there is a jump in severity for those over 50, nations can have a better idea of how many hospital beds and resources may be required in the case of an outbreak.  

Explaining the mortality rate

Previous studies by the Harvard T.H. Chan School of Public Health estimated a mortality rate of 1.4%. Data from earlier reports, and from various geographies, have suggested a range of 2% to 8%.   However, experts have maintained that this figure was likely to drop as more data regarding mild cases emerged. The researchers employed the concept of ‘infection fatality rate’ to arrive at the figure of 0.66%. Infection fatality rate takes into account all those who get infected by the pathogen - not just those who get tested and show up in official counts. Using statistical modelling to extrapolate community spread using infection rates, researchers concluded that the overall mortality rate is around 0.66%. However, removing undetected cases from the calculation placed the estimation at around 1.38%.   This does not mean that COVID-19 is not deadly. The H1N1 flu of 2009 (Swine flu) had a mortality rate of 0.02% but caused global human suffering. Precautions such as social distancing remain crucial since people from all age groups require hospitalization; failure to quell the spread will quickly outstrip health infrastructure capacity. This is already the case in New York, where Elmhurst Hospital in Queens is operating at 125% capacity.  

How do mortality and hospitalization rates change with age?

Mortality rates:  

• For those under 40 years of age, the mortality rate did not exceed 0.16%, with the likelihood of dying decreasing by decade.
• The differences began to show up in middle age; 0.3% in their 40s died, 1.25% of those in their 50s.  
• Then, a spike: 4% in their 60s and 8.6% in their 70s lost their lives. For those over 80, the data suggested a mortality rate of 13.4%.

Hospitalization rates:

• 4.3% in their 40s required hospitalization
• 8.2% in their 50s were hospitalized.
• For those in their 30s and 20s, hospitalization rates were 3.4% and 1.1% respectively.  
• Older people fared worse: 18.4% over 80 needed to be hospitalized, as did 12% of those over 60.  

For more information, read our article on   COVID-19 prevention tips for the elderly and those with chronic illnesses_._ Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.