Is influenza a coronavirus?
No. Influenza and COVID-19 come from two completely different virus families. Influenza is caused by influenza viruses. There are four types — A, B, C and D — and it is mainly A and B that make people seriously unwell.
COVID-19 is caused by a virus called SARS-CoV-2, which belongs to the coronavirus family, a completely separate group of viruses. So influenza is not a coronavirus, COVID-19 is not a strain of the flu, and neither one turns into the other.
The confusion makes sense. Both are respiratory infections, both spread through the air, and both can put you flat on your back for a week. But they’re different viruses, and that changes how you test for them, treat them and vaccinate against them.
Flu or COVID? Why symptoms alone won’t tell you
The honest answer: you can’t reliably tell them apart by how you feel. The symptom lists overlap almost entirely.
The Australian Immunisation Handbook lists the usual adult flu symptoms as fever, chills, headache, a general feeling of being unwell, loss of appetite, muscle aches, cough, sneezing and a runny nose. The Australian CDC lists the common COVID-19 symptoms as a runny or stuffy nose, cough, sore throat, fever, chills or sweats, headaches, muscle aches and fatigue. Read those two lists again and you’ll see the problem: they are almost the same list.
If you’re waiting for the loss of taste and smell to settle it, don’t. That was a hallmark of the early strains, and the Australian CDC now files changes to smell or taste under less common symptoms, alongside nausea and shortness of breath. Both infections can also be mild or cause no symptoms at all, which is exactly how they move through a workplace before anyone realises.
A test is the only way to know
If it matters which one you have, test for it. Rapid antigen tests give a result at home in 10 to 20 minutes. PCR tests are arranged through a health service and are more accurate, particularly in the first days of infection. Combined rapid antigen tests are now sold in Australia that check for COVID-19, influenza A and B, and RSV from a single swab.
If it turns out to be neither, our guide to telling a cold from the flu covers the other comparison people ask about most.
The main differences between flu and COVID-19 in 2026
Both viruses are now a standing part of Australian life rather than an emergency. Four differences still matter day to day.
Flu vaccine vs COVID-19 vaccine
Because they’re unrelated viruses, their vaccines aren’t interchangeable. A flu shot does nothing against COVID-19, and a COVID-19 vaccine does nothing against influenza. Protection against both means being vaccinated against both.
How quickly symptoms come on
On average, this is where the two viruses differ most. The Australian CDC puts flu’s onset at about two days after infection, ranging from one to four. COVID-19 usually takes three to four days, and can stretch anywhere from two to fourteen. Flu has the shorter fuse.
It’s a clue, not a diagnosis. The ranges overlap, so a fast onset leans towards flu without proving it.
What matters more for a workplace is the window before symptoms. The Handbook notes flu is detectable in the airway up to a day before you feel anything, and for around three to five days after the illness itself finishes in adults. Children can shed it for up to two weeks. That gap — infectious before you feel a thing — is why one person can seed an entire office.
One is seasonal. The other isn’t.
Flu mostly runs to a calendar. It usually peaks in winter, though the Australian CDC notes people can catch it at any time of year, and more so in the tropical north. That winter peak is why workplace clinics run ahead of it. COVID-19 doesn’t play by that rule: the Australian CDC notes its waves don’t follow a regular seasonal pattern, rising instead when a new variant circulates or immunity wears off.
For a wellbeing team that’s the practical difference. Flu you can plan for. COVID you can’t time the same way. Timing for COVID-19 vaccination follows the current advice from ATAGI, the expert group that advises the Australian Government on vaccines, rather than a calendar.
The flu vaccine is rebuilt every year
Flu viruses change slightly from one season to the next, so the vaccine is rebuilt every year to match what is actually going around. Every flu vaccine in Australia now covers three strains: two influenza A strains and one influenza B. That is what a trivalent vaccine means. A fourth strain used to be included, but it hasn’t been found circulating anywhere in the world since 2020, so it was dropped.
Do you need both a flu shot and a COVID-19 vaccine?
Yes, if you want protection against both. They target unrelated viruses, so neither one covers you for the other. Annual influenza vaccination is recommended for everyone aged six months and over.
Can you have the flu shot and a COVID-19 vaccine at the same time?
You can. This is the question we’re asked more than any other, and it has been for years.
“It’s been a regular question throughout the years — can I have the flu shot and the COVID shot at the same time?” says Aitor Aspiazu, Corporate Care’s founder and a Registered Nurse who has been running workplace flu clinics since 2011. “The answer is yes. You can have them both at the same time, and it’s quite common.”
The Handbook agrees. Influenza vaccine can be given at the same time as, or separate to, COVID-19 vaccines. There’s no waiting period, and no need to book two trips.
That matters more than it sounds. A second appointment is a second chance not to go, and if both are due, one sitting closes that gap.
Common questions about how the flu vaccine works, and the side effects people actually report, are answered on Healthdirect. If you came down with something shortly after a flu shot, our post on whether the flu shot can give you the flu explains what’s usually going on. Usually it’s one of the other viruses on this page.
What this means for your workplace
Influenza is the most common vaccine-preventable disease in Australia. Confirmed cases only ever tell part of the story: the Australian Immunisation Handbook notes that because asymptomatic or mild influenza illness is common and its symptoms are non-specific, many infections are never detected.
The honest conclusion isn’t that one of them is the dangerous one. It’s that neither is a head cold, and you can’t tell which you’re carrying by how you feel.
The Handbook puts the attack rate, the share of the community that catches flu in a year, at 5 to 10 per cent, and up to 20 per cent in some years. Where people live together, such as a household or residential care, it notes attack rates can run two to three times higher.
An office isn’t a closed population in that sense, but it does concentrate contacts, and someone can be infectious before they feel unwell.
Severe illness is more likely in older people, infants, Aboriginal and Torres Strait Islander people, pregnant women, people who smoke, and people with chronic conditions such as heart or lung disease, diabetes or a weakened immune system. It still reaches otherwise healthy adults.
If you’re weighing up a flu program for your employees, Corporate Care runs onsite workplace clinics across Australia, staffed by Registered Nurses with HESA-accredited Nurse Immuniser training. You can see how our flu vaccination programs work or request a quote.
Last updated: 21 July 2026