The novel coronavirus is "a unique virus with unique characteristics," said WHO Director-General Tedros Adhanom Ghebreyesus on March 3. However, it does share some differences and similarities with influenza, as covered in Friday's WHO Situation Report. Being aware of them may help the public take appropriate actions.
Transmission speed is an important difference between the two viruses, according to WHO.
The influenza virus spreads faster than novel coronavirus, as the former has a shorter incubation period and shorter serial interval – the time between successive cases. The serial interval of influenza is three days, while that of COVID-19 is estimated to be five to six days.
Children are important drivers of the spread of influenza virus in the community, while for COVID-19, initial data suggested that children are less affected than adults, and "further preliminary data from household transmission studies in China suggest that children are infected from adults, rather than vice versa," said WHO.
COVID-19 has a higher severe illness rate than influenza, though they have similar ranges of symptoms. Data to date indicates that 80 percent of those infected have mild or no symptoms, 15 percent are severely infected requiring oxygen and five percent are more severely infected requiring intubation.
The most vulnerable groups to severe influenza are children, pregnant women, the elderly, people with underlying chronic diseases, and those with compromised immune systems. But for COVID-19, people who are at an older age and have underlying conditions are at a higher risk for severe infection.
The mortality rate for COVID-19 appears to be higher than for seasonal influenza. "While the true mortality of COVID-19 will take some time to fully understand, the data we have so far indicates that the crude mortality ratio (the number of reported deaths divided by the reported cases) is between three to four percent," said WHO, adding that rate of seasonal influenza is usually well below 0.1 percent.
Besides, "we have vaccines and therapeutics for seasonal flu, but at the moment there is no vaccine and no specific treatment for COVID-19," said Ghebreyesus. However, he stressed that clinical trials of therapeutics are now being done, and more than 20 vaccines are in development.
Similarities between COVID-19 and influenza
Disease presentation: They both cause respiratory problems, which "presents as a wide range of illness from asymptomatic or mild, to severe disease and death."
Transmission route: Both viruses are spread by contact, droplets and fomites. Therefore, some public health measures and good respiratory etiquette are important:
– Hand hygiene
– Coughing into the elbow or tissue and immediately disposing of the tissue