Skip links and keyboard navigation

COVID-19 vaccines: everything you need to know

A nurse gives a health worker a COVID-19 vaccination
Frontline healthcare workers, quarantine and border staff were amongst the first to receive the COVID-19 vaccine in Queensland

This article was written during the Queensland response to the COVID-19 pandemic and reflects the information available at the date of publication. Please check the Queensland Government website for updated information and current health advice regarding COVID-19 and vaccinations in Queensland.

Since the Coronavirus (COVID-19) pandemic began in early 2020, people all over the globe have been waiting as scientists and researchers raced to develop vaccines for the virus.

There are currently more than 170 vaccines in pre-clinical development and more than 60 candidate vaccines are in clinical trials.

Vaccines are some of the best tools we will have for preventing or reducing the severity and long-term impacts of COVID-19 infection, protecting the vulnerable, and saving lives.

They also hold out hope of a pathway out of the pandemic and the many changes and restrictions it has brought to our usual ways of life.

You would be aware of the large amount of information (and disinformation) swirling around about COVID-19 and the vaccines.

As the COVID-19 vaccines continue to be administered in Queensland, we answer some common questions around the vaccines, explain the science behind how they work, and give you the facts you need about when and how to receive the vaccine.

What are vaccines and why do we need them?

A vaccine helps your body’s immune system fight vaccine-preventable infectious diseases.

Vaccines are generally not used to treat the disease once you have caught it but rather to prevent the disease or reduce its severity.

Your body’s immune system is amazing. It defends your body from viruses, bacteria, and other microorganisms that are harmful to it (pathogens). And it can learn. Once you have been exposed to a certain pathogen the immune system may learn to identify it and direct the body to attack it quickly and effectively the next time you are exposed to it. You may become less sick, or not sick at all. That is a form of immunity.

Medicines such as antibiotics can sometimes help your body defeat a pathogen, but in the end, it is the immune system that destroys the bug and clears it from the body.

Some infectious diseases are completely unknown to your body and your body often does not know how to protect you from them.

This is where vaccines can be a great help.

A graphic showing how vaccines and antibodies work

Why do we need vaccines if we’re already wearing masks and practising social distancing?

The measures we’ve put in place so far such as border restrictions, quarantine, mask wearing, hand washing, physical distancing, and testing help to protect all Queenslanders and will continue to be important to control the spread of the virus and its effects on the community.

But we don’t want to live under restrictions forever.

The COVID-19 vaccine is the best way to protect people long-term against severe COVID-19 disease.

Are there other benefits to getting vaccinated?

Getting vaccinated helps protect the vulnerable in our society who can’t get vaccinated themselves because they are too young, or too sick.

This is because widespread vaccination makes it more difficult for the disease to spread.

Also, the less the disease spreads, the less likely it is that new, possibly more infectious or dangerous mutations will arise.

What is herd immunity and how does it relate to COVID-19?

We reach ‘herd immunity’ when enough people are immunised to stop or slow the circulation of the disease. This reduces the likelihood of infection, which then affords protection for people who can’t be vaccinated.

What percentage of the population needs to get vaccinated before we achieve herd immunity?

The percentage changes depending on the disease and how effective the vaccine is at preventing transmission. Usually, 50% - 90% of a population needs to be vaccinated to achieve herd immunity.

Experts believe a herd immunity of 65% or higher will be needed for COVID-19, but we cannot be certain at this stage. It is an important area of research which will be ongoing as countries continue their COVID-19 vaccination programs.

What are viruses?

Viruses are extremely tiny infectious agents that consist of nucleic acid (the ‘N’ in RNA and DNA) surrounded by a protective coat of protein called a capsid.

They are so small that most of them cannot be seen under an optical microscope. The SARS-CoV-2 virus that causes COVID-19 is about 1000 times thinner than a human hair.

A British mathematician has estimated that all the SARS-CoV-2 virus particles in the world (about the same number as all the grains of sand in the world) would fit inside one soft drink can.

Viruses are unusual, as they are not really ‘alive’ when they are outside of a host cell. The debate about whether they are a form of life, or organic structures that interact with living things is still ongoing in the scientific community.

They infect all types of other life forms, from us, to animals, to plants, to microorganisms such as bacteria.

An electron microscope image of the SARS-CoV-2 virus showing it's crown-like structure

How do viruses multiply and infect other people?

Viruses do not have a cellular structure or their own metabolism, so they cannot make metabolic products or reproduce outside of a host cell. They use the cells of other living organisms to make copies of themselves by ‘hijacking’ their cellular machinery.

The SARS-CoV-2 virus that causes COVID-19 is a type of coronavirus that get their name from their ‘crown-like’ image under an electron microscope. The crown is the spike proteins that stick up off the surface of the virus.

It’s believed that the SARS-CoV-2 uses these spike proteins to help it enter host cells through the cell membrane.

Once inside, the virus uses the cell’s energy, resources and machinery to make copies of itself, or replicate.

Some of these copies leave the cell, either back through the membrane, or when the cell ruptures, and the process continues.

In the case of infected people, some of these virus particles can make their way back into the outside world through coughs, sneezes and other pathways, to infect others.

How do vaccines work?

There are different types of vaccines, and they use slightly different methods, but they have a similar effect – they prime your body’s immune system to be ready to fight an infection should you be exposed to it, by exposing it to dead or weakened versions of the virus or bacteria, or selected bits of it.

Vaccines can contain:

  • dead viruses or bacteria
  • severely weakened forms of viruses or bacteria
  • small, purified components of viruses or bacteria.

Just as we have vaccines to help protect us against diseases like measles, whooping cough, chicken pox or the flu, there are new vaccines that will help protect you against COVID-19.

What are the different types of COVID-19 vaccines?

There are different approaches to the COVID-19 vaccines being developed. Many of them target the spike protein of the virus:

  • Whole virus vaccines – use a weakened or deactivated form of the virus that causes COVID -19 (SARS-CoV-2) to trigger a protective immune response.
  • Messenger RNA (mRNA)-based vaccines – use molecules of mRNA that code for parts of the virus that causes COVID-19 – usually the spike protein that helps it enter cells. The mRNA in the vaccine instructs the body to produce harmless copies of just the spike protein and these spike proteins trigger the protective immune response.
  • Non-replicating viral vector vaccine – uses a safe, modified version of a different virus (not the virus that causes COVID-19) that enters cells in the body and uses the cell’s machinery to produce harmless copies of the spike protein of the virus that causes COVID-19 and trigger a protective immune response.
  • Protein subunit vaccine – uses purified pieces of the virus that causes COVID-19 - rather than the whole virus - to trigger a protective immune response.

A graphic showing different approaches to a vaccine

What COVID-19 vaccines are currently available in Australia?

Australia has entered into a number of agreements to secure COVID-19 vaccines, if they prove to be safe and effective. These are currently in use:

How are vaccines tested?

Vaccines are scientifically evaluated through animal testing, human clinical trials, and post-approval surveillance.

Animal testing gives information about safety before a vaccine is tested on humans.

Human clinical trials are conducted in three phases, and safety is the primary concern.

Post-approval surveillance means that once a vaccine is approved and registered for use in Australia, the TGA continues to monitor its safety and collect information on any adverse events reported.

What are the phases of human clinical trials?

Phase 1 clinical trials usually include a few dozen healthy adult volunteers and focus primarily on assessing safety, and also on demonstrating that the vaccine works. Phase 2 clinical trials have hundreds of volunteers and can include sub-groups such as older adults, children or people with pre-existing medical conditions. These trials aim to show the vaccine prompts an effective immune response in different people and confirm that it is safe.

Phase 3 clinical trials include many thousands of participants and aim to show that a vaccine is effective in preventing people from the general population getting the disease. Phase 3 trials also thoroughly assess the vaccine for safety and side effects. This phase often also involves placebo groups comparing the response of people who receive a non-COVID-19 vaccine against the real product.

Are the vaccines safe for me to have?

You cannot get COVID-19 from the vaccines.

While vaccine development and approval for COVID-19 has happened faster than usual, this is because of the urgency and scale of the pandemic. No corners have been cut, the usual processes have just been streamlined and optimised.

In response to the impacts of COVID-19 felt right around the world, unprecedented funding and collaboration occurred between regulators, governments, vaccine developers and scientists.

For COVID-19 vaccines, no testing phase has been skipped. Instead, some of these phases have been overlapped or run at the same time as each other. Having these ‘overlapping’ time frames rather than completing them one after the other has helped develop COVID-19 vaccines quickly and allow them to be available earlier to save lives.

Approvals are being given top priority by government approval agencies – such as Australia’s Therapeutic Goods Administration (TGA) – around the world.

The TGA rigorously assesses the safety, quality and effectiveness of vaccines (and all other medicines) before they are approved and registered for use in Australia.

This process is one of the toughest and most thorough in the world.

The TGA also gets independent advice on whether to register a vaccine for use in Australia. This advice comes from the Advisory Committee on Vaccines (ACV).

The ACV is an independent committee appointed by the Australian Government Minister for Health. It is composed of members with expertise in science, medicine and public health.

The ACV complements the expertise in the TGA, ensuring that its assessments of vaccines are as robust as possible.

The TGA also monitors vaccines and vaccine safety after they are supplied and used in Australia.

Are there side effects from having the vaccine?

All vaccines can have side effects, which are usually mild. Early trials of COVID-19 vaccines have reported some side effects such as pain at the injection site, fever or muscle aches. these side effects generally didn’t last for long.

The benefits of being protected against COVID-19 significantly outweigh any side effects from the vaccine.

Most side effects are immediate and short term, such as a sore arm at the injection site.

There is no current clinical evidence that suggests the vaccine will result in any long-term effects.

Can I get the vaccine if I’m planning to get pregnant, pregnant, or breastfeeding?

Pregnant women are a priority group for COVID-19 vaccination, and can receive the Pfizer vaccine (Comirnaty) or Spikevax (Moderna) at any stage of pregnancy.

If you are breastfeeding you can receive a COVID-19 vaccine at any time. You do not need to stop breastfeeding before or after vaccination.

Can I get the vaccine if I have allergies or am allergic to any of the ingredients?

Allergic reactions to vaccines or their ingredients are very rare, but they do happen. In the US, a report from the Centres for Disease Control and Prevention (CDC) suggested that severe allergic reaction (anaphylaxis) was very rare at 11.1 instances per million doses of vaccine, and that more than 80 per cent of those cases occurred in people with a history of allergic reactions.

You must not get a COVID-19 vaccine if you have had any of the following:

  • Anaphylaxis (a severe allergic reaction) to a previous dose of the same COVID-19 vaccine
  • Anaphylaxis after exposure to any ingredient of the COVID-19 vaccine.

If you have ever had a severe allergic reaction or anaphylaxis to anything else, including after receiving a vaccine, you can still get the vaccine, but you must tell the immunisation provider beforehand.

Vaccines are usually delivered in a healthcare setting by trained professionals who have the right medications and equipment on hand and know what to do if there is an issue.

How effective are the COVID-19 vaccines?

The results from the clinical trials to date have shown AstraZeneca, Pfizer, and Moderna vaccines to be effective in providing protection against COVID-19.

If as many people as possible are immunised against COVID-19, regardless of which vaccine they have, this will make a significant difference in keeping everyone safe.

More information

The vaccine is free for all Australian citizens, permanent residents and most visa-holders.

We are asking all Queenslanders to please get vaccinated.

For more information on the vaccine please visit our frequently asked questions page.

Last updated: 22 May 2022