Haven't had COVID or a vaccine dose in the past six months? Consider getting a booster
- Written by: Sathana Dushyanthen, Academic Specialist & Lecturer in Cancer Sciences & Digital Health| Superstar of STEM| Science Communicator, The University of Melbourne
Australians aged 18 and over will be eligible for a COVID booster from February 20 if they have not had a vaccine dose or infection in the past six months.
This means people aged 18–29 who have had all eligible doses will be able to get their fourth dose and those over 30 will be able to get their fifth dose. Children aged 5–17 will be eligible for a booster if they have an underlying health condition but boosters will not be rolled out to other children at this stage.
Across Australia 72.4% of the population over 16 years of age is fully vaccinated, meaning they have had least three doses of the original vaccine. But a recent poll found fewer people were willing to get a booster dose.
So why get a booster?
COVID is still circulating in the community
Over the last week, 18,590 cases of COVID were reported across Australia, an average of 2,656 cases per day. However not everyone tests for COVID or reports positive results, so the true number of cases is likely much higher.
The number of COVID hospitalisations and ICU cases has decreased compared to the previous week, to 1,838 and 53 cases respectively. Across aged care, there are roughly 198 cases this week.
While these numbers seem low, Australia also reported 226 COVID deaths in the last week of January 2023.
As winter approaches and we head inside into indoor spaces with poor circulation, we set up a perfect incubator for the virus and are likely to see case numbers rise.
You need to keep topping up your COVID immunity
Protection against COVID wanes over time. So, how many doses you have had seems to matter less than how long ago your last shot was.
Booster doses help strengthen immunity against COVID. They lower the risk of infection, severe disease and hospitalisation. However, immunity wanes at approximately four to five months after vaccination.
In an observational study from the United States, vaccine effectiveness against hospitalisation within five months of receiving the booster mRNA COVID vaccine dose was 79% during BA.1/BA.2 and 60% during the BA.4/BA.5 period. This decreased to 41% and 29% five months after vaccination.
It is still possible to contract and spread COVID after a booster dose, but breakthrough infections are often less serious.
I’ve already had COVID, so why get a booster?
The majority of Australians have had COVID at least once. By the end of August 2022, two-thirds of adults had previously been infected.
New research shows “hybrid” immunity, resulting from vaccination and contracting COVID, can provide partial protection against reinfection for up to eight months.
Hybrid immunity provides 97.4% protection against severe disease or hospitalisation for six to 12 months after an infection and vaccination.
However, immunity acquired by booster vaccination alone seems to fade somewhat faster.
Does it matter what vaccine you get?
Currently, there are a few vaccines available in Australia. These include: Pfizer, Moderna, Novavax and AstraZeneca.
Pfizer and Moderna both have bivalent vaccines against the original strain and BA.1. These are available for use as a booster, with four million doses currently available and another ten million arriving this month.
Pfizer and Moderna have had their BA.4/BA.5 version provisionally approved, however, they’re not yet available in Australia.
All available vaccines are anticipated to provide some benefit. However, Omicron-specific mRNA booster vaccines are preferred, as it seems to provide slightly better protection against severe disease than boosters using the original formulation.
Whichever vaccine you get, a booster will help protect you against severe disease symptoms, hospitalisations and reduce your chances of long COVID. It will also help to protect others around, especially if they are older, immunocompromised or from a vulnerable population.
When should I get it?
The date of your last COVID vaccine is on your COVID digital certificate accessed via Medicare or My Health Record.
If you decide to get a booster, it takes approximately 14 days for immunity to kick in. Antibody levels begin to drop after three months, before declining more steeply after four to six months.
While COVID is different to the seasonal flu, rates of COVID have previously increased over winter. There have even been reports of double infection, “flurona”.
The Australian Technical Advisory Group on Immunisation (ATAGI) particularly recommends anyone at risk of severe illness from COVID – people aged 65 years and above, or younger adults who have underlying medical conditions, disability or complex health needs – should get a 2023 booster dose.
How will I feel afterwards?
Vaccine side effects are common, such as pain and swelling at the injection site, fatigue, headache, joint or muscle pain and fever or chills. These subside within one to two days.
A few rare adverse side effects have been reported, such as thrombosis with thrombocytopenia syndrome (blood clotting disorder), myocarditis (inflammation of the heart muscle), anaphylaxis (allergic reaction), Guillain-Barré syndrome (immune system attacks nerves) and immune thrombocytopenia (low clotting disorder).
While these are rare events, it is important to know about them.
You can book your COVID booster now through the Vaccines Clinic Finder or SMS “Hey EVA” (Easy Vaccine Access) to 0481 611 382, a simple callback service to book COVID vaccines.
Authors: Sathana Dushyanthen, Academic Specialist & Lecturer in Cancer Sciences & Digital Health| Superstar of STEM| Science Communicator, The University of Melbourne
