Coronavirus: how the new ‘seasonal influenza’ would compare to the old one

Experts warn it might be too late to eradicate the coronavirus and that it will become a globally established pathogen like influenza.

Australian National University infectious diseases specialist Professor Sanjaya Senanayake says current data showed the two were nearly equally infectious. Picture: Supplied

Infectious disease specialists warn it might be too late to eradicate the novel coronavirus and that it will ultimately become an established pathogen — like influenza — that circulates the globe and erupts in seasonal outbreaks.

University of Sydney global health security specialist Adam Kamradt-Scott said the chance of COVID-19 becoming a commonplace disease still depended on the actions countries took to contain its spread.

Dr Adam Kamradt-Scott. Picture: Supplied

Even then, Australian National University’s infectious diseases specialist Sanjaya Senanayake said it was impossible to predict how the virus would continue to spread. “If it becomes a true pandemic and we all get infected and immune, will it drop away? That’s possible,” he said. “The other scenario is where it becomes a common winter virus. That’s also possible.”

Given the disease could be here to stay, it is worthwhile considering how it compares to influenza.

Which is deadlier?

Current data indicates that the COVID-19 has a higher fatality rate than influenza.

“Based on the figures emerging from China, which has 99 per cent of the world’s coronavirus cases, we see a fatality rate of 2 per cent,” Mr Kamradt-Scott said.

“Outside of China we’re seeing a rate closer to 1 per cent. If we compare this to seasonal influenza, we see a fatality rate (for the flu) of about 0.13 per cent.”

The actual fatality rate of COVID-19 could be lower, as public health officials suspect there are large numbers of infected people in countries without the ability to detect new cases who are unknowingly living with the disease.

“In that context, the fatality rate will go even lower and may be potentially around influenza rates or slightly higher,” Mr Kamradt-Scott said.

More contagious?

COVID-19 and influenza are similarly transmitted, although the former may prove to be overall less contagious as younger people are proving to make up a smaller proportion of coronavirus cases than they do influenza cases.

“It appears that both viruses are spread by droplet forms which means that if someone is coughing or sneezing near others, there is a risk of infection,” Mr Kamradt-Scott said.

Meanwhile, Mr Senanayake said current data showed the two were nearly equally infectious.

“They both have reproductive numbers of around two and a half, which means one person has the ability to infect just over two people on average,” he said.

Who is most at risk?

The people most at risk from influenza are young children and the elderly, especially those who have pre-existing medical conditions. The elderly are also susceptible to COVID-19, but data is emerging that shows children are largely avoiding being infected by it.

“Normally, with these outbreaks, we see the very young and the older adversely affected,” Mr Kamradt-Scott said. “But based on data we have at the moment, the amount of people under 19 being infected is only 2.4 per cent of the total. This is somewhat unusual to see, but it is a good sign.”

Mr Senanayake warned the comparatively low rate of children being infected should not lull us into a false sense of security.

“Really the whole world is at risk from COVID-19 because none of us are immune from it,” he said.

Immunity

There is existing global health infrastructure that ensures new strains of influenza are quickly identified and a vaccine is developed to boost immunity.

But given how new COVID-19 is, there is no comparable scheme or vaccine that will help people become more resistant to the virus, although evidence suggests people who have been infected will be more immune in the future. Mr Senanyake said research showed COVID-19 wasn’t mutating much, and that might help people build a resistance to it. “We suspect that in the short term if you get infected with COVID-19, you will be immune,” he said.

Treatments

Influenza can be battled through preventive vaccinations and treatments that fight the illness. Similar schemes are being developed for COVID-19 but they are still in their early stages.

“We have several groups working on developing a vaccine,” Mr Kamradt-Scott said.

However, he added: “Realistically, we are not likely to see a ­vaccine become available for the (novel) coronavirus for at least 12 to 18 months after the outbreak.”