There has been a rise in influenza cases in Australia this year. CSIRO immunologist, Dr Daniel Layton, answers common questions on COVID-19 and influenza in Australia this winter.
What are the risks with COVID-19 and the flu in this peak season?
Even though you can get influenza any time of year, typically the Australian influenza season runs from April to October. It’s during this time that we see the vast majority of our influenza cases. This means that you are at much higher risk of infection during these months.
Typically, we see the peak of infections in August to September. The recent rise in cases over April and May means we may see an earlier peak this year. As we’re still in the COVID-19 pandemic, it’s too early to say definitively that we’ll have higher incidence of COVID-19 during the winter months. It’s quite possible the risk of COVID-19 infection will go up over the next few months.
What happens if I get COVID-19 and the flu at the same time?
Data on this topic is still emerging. But a study published in the Lancet showed people infected with both the COVID-19 virus (SARS-CoV-2) and influenza had significantly increased odds of needing invasive mechanical ventilation and chances of dying in hospital. The study showed co-infection with respiratory syncytial virus (RSV) or Adenovirus did not have the same effect. This means COVID-19 and influenza together are a particularly nasty combination.
Why is the flu shot important as well as the COVID-19 vaccine and boosters?
Influenza, much like SARS-CoV-2, is an RNA virus. This means it carries the genetic code of the virus, so it can mutate quickly. Therefore, even if you’ve had a flu shot before, or been infected with influenza, your immune response may not be effective against the current strains. With such high rates of infection in Australia at the moment, it’s more important than ever to be protected against these viruses. Both can lead to serious disease, hospitalisation and death. So we should really use any measures we can to protect ourselves and others. Influenza, unlike COVID-19, is also known to cause severe disease in children. It’s particularly important to vaccinate them.
Do the shots interact or can I safely have all of them?
Studies have shown it can be safe to have both shots on the same day. Research also shows co-administration of COVID-19 and influenza vaccines produces a good immune response. For advice specific to you and your health conditions, chat to your GP about when to have your vaccines and boosters.
How does the flu shot work?
Much like all vaccines, the flu shot stimulates an immune response to the influenza virus by exposing your immune system to inactivated virus or parts of the virus. Your immune response is then able to store away B cells (antibody-producing cells) or T cells (killer cells) that can be recalled if you’re ever infected. This allows your body to fight the virus off more quickly and with less or no disease.
Are our immune systems weakened because we haven’t been out and about much over the last few years?
No, not really. Our immune system only really becomes ‘weak’ from an immune disorder or aging. By the time we reach adulthood, our immune systems have already been exposed to, and learned to destroy, many different viruses and bacteria. It’s not likely to forget, even if we’ve been in lockdown.
If I get the sniffles but my RAT is negative, am I safe to go out?
It’s still important that you minimise your interaction with people even if you test negative on a rapid antigen test. While they’re often very effective at detecting SARS-CoV-2 infection, they can sometimes produce a false negative result (meaning you are infected but the test is not sensitive enough). Even more importantly, if you have signs of a respiratory infection, you may be infected with influenza or another virus. And you wouldn’t want to give that to friends and family.
What else can we do to protect ourselves?
The good news is that all the things we’re now used to doing can help. One of the best measures we can take is wearing face masks in high-risk environments. Face masks are a very efficient way to reduce the spread of respiratory viruses. Also, if you have symptoms of COVID-19 or the flu, it’s best to stay home until you are well.