Influenza vaccines and COVID-19

A person can be infected with influenza (flu) at any time of the year. But in Australia flu infections tend to be more common between June and September. This is what is referred to as the ‘flu season’.

In 2021, fewer Australians were diagnosed with influenza than in previous years.^1,2 Physical distancing and hygiene measures put in place to slow COVID-19 transmission likely also slowed the spread of other infectious diseases, including influenza.³ As international borders gradually reopen and people start moving about, including those who have recently returned from overseas, the rate of influenza transmission is expected to increase. This may potentially occur outside of the usual flu season.

‘Although the current rate of influenza infections appears low, the flu can still cause serious illness, particularly among those at high risk such as the elderly,’ says Dr Anna Samecki, medical adviser at NPS MedicineWise.

The same is true for COVID-19 infections in the Australian community. Public health advice about maintaining physical distance, wearing masks and practicing good hygiene have helped keep community levels of transmission low. But outbreaks have occurred and will continue to do so as long as the SARS-CoV-2 virus (that causes COVID-19 infections) is around. 

As with influenza vaccinations, having a COVID-19 vaccination provides an extra level of protection against being infected and also helps slow the spread of infection to others who may be more vulnerable to severe complications.

The flu is caused by influenza viruses of types A, B, C or D.⁴ Most flu-related illnesses are caused by influenza type A or B viruses. Influenza viruses are constantly changing parts of their genetic code (through mutations). 

Over time a virus may become different enough that it is no longer recognised by a person’s immune system. This increases the chance of infection and of this variant being passed on to other people to become the dominant strain causing illness.

Constant mutation means that the dominant strain one year may not remain the dominant strain in following years.⁵ This is why the influenza vaccines change each year – to better match the likely strains causing infection. It is also why people are advised to have a flu jab every year – so they can produce the antibodies best matched to defend against the influenza viruses currently in circulation.

Whether you have had flu previously or have had an influenza vaccination in the past, current evidence suggests that any antibodies you made will become less protective with time.⁵ This may be because the level of antibodies in your body declines, or because the antibodies you have do not work against the influenza types currently causing infection.

In Australia, the influenza vaccine rollout is guided by advice from the World Health Organisation (WHO). It recommends which influenza strains should be included in the next season’s vaccines, based on analysis of recent flu seasons.⁵

These recommendations are made in September for countries in the southern hemisphere. The Australian Influenza Vaccine Committee meets with the Therapeutic Goods Administration to consider the WHO recommendations and confirms the strains to be included in Australian flu vaccines.⁶

This year, eight quadrivalent influenza vaccines have been approved for use in Australia.^7,8 Quadrivalent flu vaccines protect against four of the most common influenza strains currently causing infections.

Although there are multiple influenza vaccines available, they are not all for general use.

Each year ATAGI makes recommendations on the influenza vaccines that are appropriate for each age group. These recommendations are informed by clinical trials, information gathered once the vaccines are in use, and data collected from WHO.

‘Certain age groups are particularly vulnerable to the flu and have higher rates of complications and hospitalisations’, says Dr Samecki. ‘That is why some flu vaccines have age restrictions, as they are designed to boost the immune response in those most vulnerable. A good example is FluadQuad, which is specifically for adults aged over 65 years.’

The Australian Government has set aside millions of influenza vaccine doses as part of the National Immunisation Program (NIP). The NIP provides these doses for free to people in our community who are most at risk from complications if they are infected with influenza.

People who are not eligible for a flu jab through the NIP can arrange to receive their vaccination through their GP or another recognised immunisation provider. In all cases there may be costs involved if a consultation is needed. It is wise to check about costs before going to have your vaccination, even if you think you are eligible under the NIP.

A summary statement about the influenza vaccines available for use in Australia in 2021 – Updated December 2021 is available from ATAGI.

If you have any questions about which flu vaccine is best for you, speak to your trusted health professional or call the National Immunisation Information Line on 1800 671 811 for general advice and information about immunisation, Monday to Friday from 8:30 am to 5 pm Australian Eastern Standard Time.

You can also use the NPS MedicineWise Medicine Finder to read, download or print the Consumer Information Leaflet for each of these vaccines.

COVID-19 has been around for almost 2 years. A lot of research has been conducted on the SARS-CoV-2 virus in that time, including the development of almost 300 different vaccines (some at laboratory phase, other in trial phases).⁹ We have also seen a number of variants emerge as the SARS-CoV-2 virus undergoes natural changes to its genetic code (mutations).¹⁰

Clinical trials are underway to understand how effective the currently available COVID-19 vaccines are against variant strains of the SARS-CoV-2 virus. Some early or preliminary reports suggest that the vaccines can still protect against infections caused by variant strains but not as well as they do against the original SARS-CoV-2 virus.^11-15 Some companies are already working on new vaccines that better target variants, so it is possible that booster or seasonal COVID-19 vaccines may be recommended in the future if variant strains continue to emerge.

It is still unclear how long immunity lasts after COVID-19 vaccination. Natural immunity may be short-lived, with reinfection of COVID-19 likely to occur within 3 months.¹⁶ Ongoing studies for the mRNA vaccines by Pfizer/BioNTech and Moderna have reported immunity from the virus lasting 6 months after a second dose.^17,18

In Australia, four of the most extensively tested and studied vaccines have provisional approval for use: Comirnaty (Pfizer/BioNTech); Vaxzevria (AstraZeneca; previously COVID-19 Vaccine AstraZeneca; ChAdOx1-S); COVID-19 vaccine Janssen (Janssen-Cilag); and Spikevax (Moderna). At the moment the expert clinical recommendation is that each eligible person has two doses of the same vaccine to provide maximum immunity. Needing multiple doses is common for many other vaccines that people may also receive during their lifetimes.

Yes. A flu vaccine will not protect you against COVID-19. A COVID-19 vaccine will not protect you from being infected with the flu.

Influenza and COVID-19 are both viral infections that affect the respiratory (breathing) system. But they are caused by different viruses. COVID-19 is caused by the coronavirus SARS-CoV-2. Influenza is caused by influenza viruses.

The vaccines being developed against COVID-19 are specific to the SARS-CoV-2 virus. These vaccines trigger your immune system to make antibodies that are specific to the SARS-CoV-2 virus. These antibodies cannot work against any other type of virus.

Flu vaccines are developed to target the types of influenza viruses that are likely to be most common in the approaching flu season. A flu vaccine can trigger your body to create antibodies to fight influenza viruses. It will not help trigger an immune response to SARS-CoV-2.

COVID-19 and the flu are both highly contagious diseases. The best way to prevent the spread of either infection is to get vaccinated. You should also continue to practice good hygiene (washing hands regularly, coughing and sneezing into a tissue or your elbow etc) and physical distancing to protect yourself and others – especially those who are unable to be vaccinated against one or both of these diseases.

The Australian Technical Advisory Group on Immunisation (ATAGI) and the Commonwealth Department of Health have advised that a flu vaccine can be given at any time before or after, or with a COVID-19 vaccine. This allows your immune system time to fully respond to each vaccine. In the unlikely scenario that you have a reaction to one of the vaccines, it also makes follow-up and side effect reporting a lot easier.

An ideal time to get the flu vaccine, if available, could be at the same time as the COVID-19 booster vaccine.

Use the COVID-19 Vaccine Eligibility Checker to find out when you are able to plan your COVID-19 vaccine.

The timing of your vaccine may be influenced by your travel plans. If you are planning international travel, ensure that you have had a flu vaccine before leaving. If you are returning from the Northern Hemisphere in late 2021 or early 2022, it is recommended that you get a flu vaccine in the country from which you are leaving (where available) before departure.

After receiving a vaccination, including for influenza or COVID-19, some people may have unwanted side effects. Read more about when to report these side effects, and why that information is important.

The Australian Government Department of Health also has information about reporting adverse side effects following a COVID-19 vaccination - What happens after I am vaccinated for COVID-19?

Information about flu vaccines

• For more information on influenza (flu) read the resource from the Australian Immunisation Handbook or the  summary available on the Department of Health website
• Download the ATAGI advice on influenza and COVID-19 vaccines
• Call the National Immunisation Information Line on 1800 671 811 to ask any vaccine-related questions
• Find out more about flu vaccines on our website

Information about COVID-19 vaccines

• Read the Department of Health resources on COVID-19 vaccines
• Find out more about COVID-19 vaccines on our website

Information about vaccines and adverse events

• The Department of Health’s resource ‘What happens after I am vaccinated for COVID-19?’ has helpful information about adverse reactions to COVID-19 vaccines
• If you want to report or ask questions about any medicine or vaccine related side effect, you can call NPS MedicineWise Adverse Medicine Events (AME) Line on 1300 134 237, 7 days a week 8 am – 8 pm AET
• Report an adverse reaction to a vaccine by filling out an online form on the TGA website