These COVID-19 vaccine FAQs have been designed to address common queries relating to COVID-19 vaccine development, rollout plans, effectiveness and storage.

Please also see our other COVID-19 FAQs for more information on other COVID-19 related topics:

For ease of reference, information has been categorised as per the below themes:

This page will be updated on a regular basis as further information becomes available regarding COVID-19 vaccines.

For questions that have not been addressed on this page or our dedicated COVID-19 resource page, please email for further clarification.

Vaccine development process

  • How can the COVID-19 vaccine be safe when it has been developed so quickly?

    COVID-19 vaccine development is happening “faster than usual” because of the global impact of the pandemic and the urgent need for a vaccine(s). Vaccines have traditionally been developed in consecutive sequential stages – with preclinical trials followed by phases I, II and III, often with large gaps of time in-between phases awaiting funding or manufacturing scaleup. With COVID-19, this process has been made more efficient by running one phase while simultaneously also preparing and/or recruiting for the next phase.

    It is important to note that COVID-19 vaccine candidates must pass through the exact same rigor and phases of clinical trials and do not miss any important safety and quality checks or steps. Approval is only given if the vaccine meets the appropriate requirements for safety and efficacy.

    Refer to MVEC: Vaccine development and safety, including “The Road to a COVID-19 Vaccine” animation for more information.

  • What is involved in the phases of clinical trials?

    During vaccine development, initial safety testing of a vaccine candidate occurs in two stages. Stage one involves preclinical assessment both in the laboratory and also animal trials.  Stage two involves the evaluation of the vaccine candidate in three phases of clinical trials in human volunteers.

    Phase I clinical trials: the vaccine candidate is given to small numbers (25–50) of healthy adults with the primary goal of assessing safety.

    Phase II clinical trials: If the vaccine candidate is found to be safe in Phase I, it is then given to hundreds of participants to determine: how effectively it stimulates immune responses; optimal dose regimen; and whether its side effect profile.

    Phase III clinical trials: If the vaccine candidate is found to be effective and safe in both Phase I and II, it is then given to many thousands of participants to test its effect on protecting large populations from the target disease and to determine if there are any uncommon, serious or severe side effects.

    Refer to MVEC: Vaccine development and safety for more information.

  • What does provisional approval mean and how does it differ from normal registration?

    In Australia, the Therapeutic Goods Administration (TGA) is responsible for assessing vaccines and other medicines for use in Australia. A number of sponsors of COVID-19 vaccines have applied to the TGA for registration using the so-called ‘provisional approval pathway’.

    The provisional pathway is only one of a number of pathways that a sponsor may use to apply for the approval of a vaccine. It is very important to note that the TGA evaluation process under the ‘provisional pathway’ still involves a full review of the vaccine and its associated safety data, noting that the TGA does not have a mechanism for emergency use authorisations (EUA) that have been granted in other countries. The provisional approval is for an initial period of 2 years. Sponsors may then apply for ‘full registration’ when there is more clinical data to confirm the safety of the vaccine.

    Refer to MVEC: Provisional registration of COVID-19 vaccine(s) in Australia for more information on provisional approval.

    Refer to TGA: COVID-19 vaccines for further information on the role of the TGA and their internal processes.

  • How can we be sure that the vaccine manufacturing process is safe?

    Like any medication in development, vaccine candidates must undergo rigorous testing procedures and scientific evaluation to prove not only their effect on the targeted disease, but also to determine their safety – before being licensed and registered for use in vaccination programs.

    In all three clinical trial phases, safety is continually assessed as data is gathered and a vaccine must pass all these phases before it can be considered for registration for use by the TGA. By the time a vaccine is registered, safety would have been assessed in tens of thousands of clinical trial participants and this safety data would have been rigorously evaluated by the TGA and other international drug regulatory bodies.

    The quality, sterility, potency and purity of each vaccine batch is also assessed by the TGA prior to being supplied to Australia, as is the quality of selected batches after they have been supplied.

    Once a vaccine is approved, it continues to be tested in a process known as post-licensure surveillance.

  • Who funds a vaccine trial?

    Vaccine research and development is often funded by a range of sources including governments, bilateral and multilateral organisations, non-government organisations and the private sector (including pharmaceutical companies). Never before has one vaccine received so much investment and global collaboration – this is a major reason why there are multiple COVID-19 vaccines that have been able to progress so efficiently with minimal pauses through to the final phase III large clinical trials.

    A prominent funding source for many COVID-19 vaccines is the COVAX Facility. COVAX is coordinated by Gavi (the Vaccine Alliance), the Coalition for Epidemic Preparedness Innovations (CEPI) and the World Health Organization. COVAX pools funding from over 180 governments, global health organisations, private sector and manufacturers to support research, development and manufacturing of multiple COVID-19 vaccine candidates.

    Refer to MVEC: COVAX Facility for more information about COVAX.

Vaccine rollout

  • What COVID-19 vaccine agreements are in place for Australia?

    The Australian Government has entered into five agreements for the supply of COVID-19 vaccines, if they prove safe, effective and are licensed for use within Australia. These agreements include:

    1. Comirnaty™ (Pfizer/BioNTech COVID-19 vaccine) – provisional registration granted on January 25, 2021
    2. COVID-19 AstraZeneca vaccine – provisional registration granted on February 16, 2021
    3. Novavax COVID-19 vaccine candidate – provisional determination granted on January 19, 2021
    4. COVAX Facility
    5. Moderna COVID-19 vaccine candidate – provisional determination granted on June 24, 2021

    The University of Queensland COVID-19 vaccine candidate previously had an agreement with the Australian government, however will no longer be proceeding to Phase 3 trials.

  • Why will the vaccine only be offered to some groups initially?

    There is significant demand for COVID-19 vaccines globally, meaning that the initial vaccine doses will be limited. The priority groups and vaccine allocation will be decided by the Commonwealth with those groups identified as the highest risk offered vaccination first, before subsequent vaccination of the general population.

    More information can be found at Australian Government Department of Health: When will I get a COVID-19 vaccine?

  • Who is eligible for a COVID-19 vaccine?

    COVID-19 vaccine priority groups are decided by the Commonwealth, based on expert advice from the Australian Technical Advisory Group on Immunisation (ATAGI).

    The following people are now eligible for COVID-19 vaccination:

    • Quarantine and border workers
    • Health care workers
    • Aged care and disabilty staff and residents
    • All adults from 40 year of age
    • All Aboriginal and Torres Strait Islander people from 12 years of age
    • Anyone over 12 years of age with an underlying medical condition or significant disability
    • NDIS participants aged years 12 and over, and carers of NDIS participants of any age
    • Critical and high risk workers aged 16 and over (including defence, police, fire, emergency services and meat processing)
    • Temporary visa holders aged under 50 years who are currently in Australia and have been approved for return travel to Australia through the travel exemption process

    Individual states may have varied approaches to vaccine eligibility criteria based on the local COVID-19 situation and vaccine supply. For information relating to the Victorian rollout please refer to Victorian Department of Health: COVID-19 vaccines.

  • Will there be enough vaccines to immunise all Australians?

    Over time, there will be adequate supplies of multiple COVID-19 vaccines for the entire Australian population There are also agreements in place to address the need for long term immunity and the emergence of strain variants.

  • How can I access a COVID-19 vaccine?

    COVID-19 vaccines are currently being delivered in Victoria via state-run mass vaccination clinics as well as through Commonwealth appointed General Practice clinics.

    Individuals who are eligible for vaccination can book an appointment in a mass vaccination clinic by calling the Victorian Coronavirus Hotline on 1800 675 398. Alternatively some venues do accept walk ins. Further information can be found via Victoria Department of Health: COVID-19 vaccines.

    Eligible individuals can also contact their local GP clinic to make an appointment for vaccination.

  • How and where will the vaccine administration be registered/recorded?

    It is mandatory for every COVID-19 vaccine administered within Australia to be recorded on the Australian Immunisation Register (AIR). The AIR records any vaccine doses administered, the date of administration and the specific brands given.  It also identifies any vaccines that are due or overdue according to the National Immunisation Program (NIP). Immunisation history statements (IHS) can also be generated from AIR.

  • I am interested in being part of the Victorian COVID-19 workforce and delivering COVID-19 vaccines, what are the training requirements and how do I apply?

    COVID-19 vaccines in Victoria can be delivered by traditional authorised immunisers (medical staff, nurse immunisers, nurse practitioners and accredited pharmacist immunisers) and additional healthcare professionals (Aboriginal health practitioners, pharmacists, pharmacy technicians, registered nurses, enrolled nurses, midwives, paramedics and nursing and midwifery students) who have been authorised to join the emergency workforce.

    Prior to administering any COVID-19 vaccine, specific training and education is required with variations in training requirements based on the profession.

    Details on the training requirements and how to join the workforce can be found on our reference page COVID-19 vaccine delivery: workforce training and application process


  • How do we know a vaccine is effective?

    In vaccine clinical trials it is important to understand the difference between efficacy versus effectiveness. Efficacy is calculated from a Phase III clinical trial and effectiveness is the vaccine’s impact in a real world setting once the vaccine is administered in the general public.

    Vaccine clinical trials represent a strictly controlled setting; for example, trial participants are closely monitored and if two vaccine doses are required, the doses will be given with exactly the same interval for everyone. All vaccines that are eventually registered will have proved they have adequate efficacy through large Phase III trials.

    Efficacy is calculated by assessing how many people develop COVID-19 in the group receiving the COVID-19 vaccine compared to the placebo (or control) group. For example, if 100 people develop COVID-19 disease in a trial, and 95 of these were in the placebo group (meaning only 5 people in the vaccine group developed disease), the vaccine efficacy would be calculated at 95%. In other words, the vaccine prevented 95 out of 100 people from contracting COVID-19 disease. Efficacy is usually calculated after the full vaccine course; for most COVID-19 vaccines this is after two doses.

    In a real-world setting, it is expected that there will be lower levels of protection due to multiple variables, such as wider differences amongst people receiving the vaccine (eg. different ethnicities or underlying medical conditions). Hence vaccine effectiveness is expected to be slightly lower than what is reported in initial clinical trial results. Vaccine effectiveness in the real world will continue to be monitored in post-licensure studies.

  • Will the vaccine be effective in children?

    Currently, COVID-19 vaccines are not registered for use in Australia in children aged less than 12 years. To date, COVID-19 infections have produced more severe disease outcomes in adults and the older population, with children generally experiencing milder symptoms. For this reason, initial COVID-19 vaccine clinical trials and vaccine rollouts have focused on the adult population.  

    Clinical trials are currently underway to determine the safety and efficacy of various COVID-19 vaccines in children. For more information, please refer to our reference page COVID-19 vaccination in children

  • Can the vaccine be given to people who are immunosuppressed?

    ATAGI recommends COVID-19 vaccination for all immunosuppressed people due to an increased risk of developing severe disease if infected with SARS-CoV-2. Due to the restricted eligibility criteria in early vaccine clinical trials, there is currently minimal data on the safety and efficacy of COVID-19 vaccination in this group. 

    It is anticipated that the immune response to vaccination may be reduced in this patient group depending on the level of immune suppression. Hence, when vaccinating immunocompromised people, they should also be counselled about this reduced efficacy and the need to continue other prevention measures such as social distancing and mask wearing.

    Further information can be found via our reference page: COVID-19 vaccines in people with immunocompromise.

  • What is herd immunity?

    Herd immunity describes when a certain proportion of the community is immune to a specific pathogen (in this case virus). It can only be induced by vaccination; never in history has any virus infection been eliminated because of immunity by natural infection.

    Herd immunity is achieved when more than 60-70% of people in a population are vaccinated against a particular illness. At this level of population immunity, there are fewer people that the pathogen can infect and hence this self-limits the spread of the pathogen.

    Please see more information about herd immunity from the Australian Academy of Science.

  • Can COVID-19 vaccines be used to prevent disease in patients who have already been identified as contacts of a COVID-19 positive case?

    COVID-19 vaccine administration is not recommended for post-exposure prophylaxis.

    Please refer to COVID-19 vaccination – ATAGI clinical guidance on COVID-19 Vaccine in Australia in 2021 for more information.


  • How should COVID-19 vaccines be stored?

    The storage environments required for the COVID-19 vaccines being used within Australia vary depending on the brand of vaccine.

    mRNA vaccines (Comirnaty™ and Moderna COVID-19 vaccines) require ultra-low cold chain storage and transport conditions, resulting in additonal logistical considerations for purpose built freezers and dry ice. Once defrosted they will only remain stable for a limited amount of time.

    COVID-19 AstraZeneca and the Novavax COVID-19 vaccine candidate can be stored in standard vaccine cold chain temperatures of between 2°C to 8°C.

    For more information on cold chain please refer to our reference page Cold chain.

  • Are multi-dose vials safe? Why are they being used?

    Multi-dose vials (MDV) are safe as long as each dose is prepared appropriately using aseptic technique. They should be kept and accessed in a dedicated clean medication preparation area and away from immediate patient treatment areas. This is to prevent inadvertent contamination of the vial and cross contamination between patients.

    MDVs are cheaper to produce and occupy less cold-chain capacity. In the context of the COVID-19 pandemic; improved efficiency of production and storage is vital when millions of doses must be produced quickly.

    To learn how to safely prepare and store multi-dose vials please refer to MVEC’s immunisation reference page Multi-dose vials as well as MVEC’s eLearning package on the Use of multi-dose vials accessible via the education portal.

Authors: Daniela Say (MVEC Immunisation Fellow), Georgina Lewis (SAEFVIC Clinical Manager, Murdoch Children’s Research Institute), Rachael McGuire (MVEC Education Nurse Coordinator) and Francesca Machingaifa (MVEC Education Nurse Coordinator)

Reviewed by: Rachael McGuire (MVEC Education Nurse Coordinator)

Date: June 8, 2021

Materials in this section are updated as new information and vaccines become available. The Melbourne Vaccine Education Centre (MVEC) staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family’s personal health. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult a healthcare professional.