The WHO has made a comparison between both diseases and its report indicates the following:
As the COVID-19 outbreak continues to evolve, comparisons have been made with influenza. Both cause disease respiratory problems, however there are important differences between the two viruses and how they are spread. This has important implications for public health measures that can be implemented to respond to each virus.
How are COVID-19 and influenza viruses alike?
First, COVID-19 and influenza viruses have a similar disease presentation. That is, they both cause respiratory problems. The disease, which occurs as a wide range of illnesses, from asymptomatic or mild to serious illness and death. Second, both viruses are transmitted by contact, droplets, and fomites. As a result, the same public health measures, such as hand hygiene and good respiratory etiquette (coughing in the elbow or in a handkerchief and getting rid of tissue immediately), are important actions everyone can take to prevent infection.
How are COVID-19 and influenza viruses different?
Transmission speed is an important point of difference between the two viruses. Flu has a minor
Median incubation period (the time from infection to the onset of symptoms) and a shorter serial interval (the time between successive cases) than the COVID-19 virus. The serial interval for the COVID-19 virus is estimated to be 5-6 days, while for the influenza virus, the serial interval is 3 days. This means that influenza can spread faster than COVID19.
Also, transmission in the first 3-5 days of illness, or potentially pre-symptomatic transmission – transmission of the virus before symptoms appear: is a major driver of influenza transmission. On the contrary, while we are learning that there are people who can eliminate the COVID-19 virus, 24-48 hours before the onset of symptoms, at present, this does not seem to be an important transmission engine.
The reproductive number, the number of secondary infections generated by an infected individual, is understood to be between 2 and 2.5 for the COVID-19 virus, greater than for influenza. However, the estimates for both
COVID-19 and influenza viruses are very context and time specific, making direct comparisons difficult.
Children are important drivers of influenza virus transmission in the community. For the COVID-19 virus, initial data indicates that children are less affected than adults and that clinical attack rates in the 0-19 age group are low.
Other preliminary data from home transmission studies in China suggest that children are infected by adults, rather than vice versa.
Although the symptom range of the two viruses is similar, the severely ill fraction appears to be different.
For COVID-19, the data to date suggests that 80% of infections are mild or asymptomatic, 15% are serious infections, require oxygen, and 5% are critical infections that require ventilation. These fractions of serious and critical infection.
People at increased risk for severe influenza infection are children, pregnant women, the elderly, and people with chronic medical conditions and those who are immunosuppressed. For COVID-19, our current understanding is that advanced age and underlying conditions increase the risk of serious infection.
COVID-19 mortality seems higher than influenza, especially 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 death rate (the number of reported deaths divided by reported cases) is between 3-4%, the infection death rate (the number of reported deaths divided by the number of infections) will be lower. For seasonal influenza, mortality is usually well below 0.1%. However, mortality is largely determined by access and quality of medical care.
What medical interventions are available for COVID-19 and influenza viruses?
While there are a number of therapies currently in clinical trials in China and more than 20 vaccines in
development for COVID-19, there are currently no vaccines or therapies licensed for COVID-19. Unlike,
Antivirals and vaccines available for the flu. Although the influenza vaccine is not effective against the COVID-19 virus.
Influenza viruses can spread faster than the new coronavirus, while their average incubation period and the interval between infection and subsequent transmission are shorter: about three days for the first and