In the penultimate month of 2020, more than 47 million people have been diagnosed with new crown pneumonia worldwide. As the northern hemisphere enters autumn and winter, outbreaks are once again severe in some countries. How high is the level of transmission and severity of infection of the new coronavirus? Today, Nature, a leading academic journal, published a research paper online in the form of Accelerated Article Preview. Scientists from the University of Cambridge in the UK and the Pasteur Institute in France combined epidemiological data from 45 countries to make the calculations.
The researchers point out that inepties in available data make it difficult to estimate the scale and severity of the new coronavirus epidemic. Deaths are often used as key indicators for assessing transmission rates and the severity of infections, but a simple comparison of the total number of deaths may misrepons the basic level of transmission of the new coronavirus, as mortality rates for older persons reported vary widely from country to country.
Another indicator is the sero-positive rate, which is how many people are estimated to have antibodies to the new coronavirus through serological surveys. Antibodies indicate whether a person has been infected with the new coronavirus at some point, and therefore can indicate the infection rate of the entire population. However, this type of data is affected by detection capabilities.
In this study, to more accurately assess the rate of transmission and mortality of new coronavirus infections, the team built a model framework using official data on deaths from new coronary pneumonia in all ages from 45 countries, as well as 22 national serological findings.
“Our model shows that among people under 65 years of age, the new crown mortality rate by age is highly consistent across countries and regions and can be used as a reliable indicator of the number of infections in the population as a whole. This is critical in most cases where infections go undetected. Professor Megan O’Driscoll, lead author of the study.
Using data on deaths in the under-65 age group alone, the model estimates that in the countries assessed, an average of 5 per cent of the population had contracted the new coronavirus by 1 September this year. The model results also suggest that in some South American countries, there may have been higher transmission.
The researchers estimated the rate of infection mortality (infection-to-fatality, IFR), which is the proportion of people infected with the virus who may die as a result. In different countries, the proportion of deaths from infection with the new crown is consistently the lowest in the 5-9 age group. For every 5 years of age, the infection mortality rate increased by 0.59 per cent.
The model estimates the death rate from new crown infections in 45 countries, including China (Photo: References; click to see the graph)
According to IFR, the researchers estimated the expected number of deaths among people over 65 years of age and compared the estimates with the reported deaths in this age group, and found differences in figures between countries. In countries such as the UK, Canada and Sweden, for example, new deaths of people aged 65 and over were reported higher than expected because of multiple outbreaks in nursing homes. In contrast, some South American and Asian countries reported significantly fewer deaths over the age of 65 than expected, and the authors analyzed a potential explanation for the under-reporting of deaths from neo-corona pneumonia in older people.
In the abstract, the researchers say monitoring the level of transmission of the new coronavirus and the severity of infection is an important means of guiding the response to the epidemic, and that this model framework can help countries assess the progress of the new coronavirus. We also look forward to this information to help countries and regions around the world to prevent and control the outbreak, so that the world can get back on track at an early stage.