The attack rate or transmissibility (how rapidly the disease spreads) of a virus is indicated by its reproductive number (Ro, pronounced R-nought or r-zero), which represents the average number of people to which a single infected person will transmit the virus.
WHO's estimated (on Jan. 23) Ro to be between 1.4 and 2.5.
Other studies have estimated a Ro between 3.6 and 4.0, and between 2.24 to 3.58.
Preliminary studies had estimated Ro to be between 1.5 and 3.5.
An outbreak with a reproductive number of below 1 will gradually disappear.
For comparison, the Ro for the common flu is 1.3 and for SARS it was 2.0.
The novel coronavirus' case fatality rate has been estimated at around 2%, in the WHO press conference held on January 29, 2020. However, it noted that, without knowing how many were infected, it was too early to be able to put a percentage on the mortality rate figure.
A prior estimate had put that number at 3%.
The fatality rate can change as a virus can mutate, according to epidemiologists.
For comparison, the case fatality rate for SARS was 10%, and for MERS 34%.
The median age of cases detected outside of China is 45 years, ranging from 2 to 74 years.
71% of the cases were male.
A study of 138 hospitalized patients with NCIP found that the median age was 56 years (interquartile range, 42-68; range, 22-92 years) and 75 (54.3%) were men.
- People of all ages can be infected by the novel coronavirus COVID-19.
- Older people and people with pre-existing medical conditions (such as asthma, diabetes, heart disease) appear to be more vulnerable to becoming severely ill with the virus.
For more information from the WHO regarding novel coronavirus: WHO page on Novel Coronavirus (2019-nCoV).
- Every year an estimated 290,000 to 650,000 people die in the world due to complications from seasonal influenza (flu) viruses. This figure corresponds to 795 to 1,781 deaths per day due to the seasonal flu.
- SARS (November 2002 to July 2003): was a coronavirus that originated from Beijing, China, spread to 29 countries, and resulted in 8,096 people infected with 774 deaths (fatality rate of 9.6%). Considering that SARS ended up infecting 5,237 people in mainland China, Wuhan Coronavirus surpassed SARS on January 29, 2020, when Chinese officials confirmed 5,974 cases of the novel coronavirus (2019-nCoV). One day later, on January 30, 2020, the novel coronavirus cases surpassed even the 8,096 cases worldwide which were the final SARS count in 2003.
- MERS (in 2012) killed 858 people out of the 2,494 infected (fatality rate of 34.4%).