These COVID-19 vaccine FAQs have been designed to address common queries relating to COVID-19 vaccine administration technique and vaccine schedules.

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 contact us here.

Administration technique

  • What do I do if there was leakage of diluent when reconstituting Comirnaty (Pfizer)?

    If you have injected most of the diluent into the vial and there has been no breach in infection control, the vaccine can still be used.

    If there is uncertainty as to how much diluent was lost, you may still use the vial provided if you are able to draw up at least 6 doses from a Paediatric Pfizer vial (orange cap) or 4 doses from a ≥ 12 year old Pfizer vial (purple cap).

    To read more please refer to Australian Government Department of Health: COVID-19 vaccine allocations, storage and handling.

  • Can COVID-19 vaccines be given subcutaneously?

    Vaxzevria (AstraZeneca), Comirnaty (Pfizer), Nuvaxovid (Novavax) and Spikevax (Moderna) should be administered via intramuscular injection. There is no safety or efficacy data relating to subcutaneous administration.

  • When administering a COVID-19 vaccine the syringe disconnected from the needle and I am not sure how much of the dose my patient received, what should I do?

    If the process of administering a vaccine is interrupted and most of the dose has not been given, repeat the whole dose as soon as practicable. If you have given most of the dose, you do not need to give the dose again. Please contact your safety service if there are any concerns/questions.

    To read more please refer to the Australian Immunisation Handbook: Administration of vaccines.

  • What is the recommended site for injection for patients who have had axillary lymph nodes removed/have a history of lymphoedema?

    There is no strong evidence to suggest that vaccine administration into the deltoid will increase the likelihood of lymphoedema in patients who have had lymph nodes removed or have a previous history of lymphoedema.

    Vaccine administration into the deltoid of the unaffected arm may be preferred, alternatively intramuscular injection into the vastus lateralis (thigh) can be considered.

    Please refer to MVEC: Administration of injected vaccines – correct technique or Breastcancernow.org: Can I have coronavirus vaccine if I’ve had breast cancer treatment? for more information.

  • Can COVID-19 vaccines be co-administered with other vaccines?

    For most people, COVID-19 vaccines can be co-administered on the same day as other vaccines, including influenza, routine scheduled vaccines and maternal pertussis vaccines.

    There is emerging safety evidence supporting the co-administration of COVID-19 vaccines and influenza vaccines. There is currently limited data on the co-administration of COVID-19 vaccines with other routine vaccines however the benefits of ensuring timely vaccination outweighs potential risks associated with immunogenicity, fever or local side effects.

    Where possible it is preferred that infants and children aged 6 months – 5 years receiving Spikevax (Moderna), allow an interval of 7-14 days between administration of Spikevax (Moderna) and other vaccines to minimise the risk of adverse events such as fever.

    For more information please refer to Australian Government Department of Health: Clinical recommendations for COVID-19 vaccines.

  • What is the recommendation for administering COVID-19 vaccines to individuals with bleeding disorders?

    COVID-19 vaccines should be administered via intramuscular injection only. People who are taking anticoagulant therapy or have a history of a bleeding disorder are at higher risk of haematoma formation following intramuscular injection. Prior to vaccine administration, patients should be advised of this risk.

    The correct needle size and length should be used and firm pressure should be applied to the site (no rubbing) for at least 2 minutes following immunisation.

    Subcutaneous administration is not recommended due to a lack of safety and efficacy data regarding this route of administration.

    For further information please refer to the Australian Immunisation Handbook.

Vaccine schedules

  • Can COVID-19 vaccines be used interchangeably (eg. using a different brand for the first and second dose)?

    Where possible, it is preferred that a primary course of COVID-19 vaccination is completed with the same brand. However, if there is a specific medical contraindication or precaution, lack of vaccine availability, or brand preference by an individual, then an alternate brand can be used to complete a course.

    When using mixed schedules, the recommended interval between the first and second doses is 4-12 weeks. A longer interval will be accepted if this is not possible.

    For further information refer to ATAGI clinical advice on use of a different COVID-19 vaccine as the second dose in special circumstances.

  • What are the recommendations for booster doses of COVID-19 vaccines in Australia?

    A single booster dose is recommended for all individuals ≥ 16 years, and a select group of 12-15 year olds, 3 months after a primary course of COVID-19 vaccination is complete. An additional “winter” booster is recommended for some individuals ≥ 16 years who are at an increased risk of severe COVID-19 disease. This winter dose can be administered ≥ 3 months after receiving the first booster.

    The preferred vaccine brands for booster doses in adults aged ≥ 18 years are Comirnaty (Pfizer) or Spikevax (Moderna). Comirnaty (Pfizer) is the only vaccine brand registered for use as a booster in individuals < 18 years. Whilst Nuvaxovid (Novavax) is not registered for use as a booster dose, ATAGI recommends that it may be used in individuals ≥ 12 years of age where no other vaccine brand is suitable (eg. allergy).

    Vaxzevria (AstraZeneca) is no longer recommended for use as a booster dose. Individuals who have already received Vaxzevria (AstraZeneca) as their booster dose do not need a repeat booster dose of an alternate brand.

    Adolescents who received a primary course of COVID-19 vaccination when they were < 12 years of age, can receive a booster dose once they are age-eligible/more than 3 months has elapsed since completing their primary course (whichever is later).

    Booster doses are not recommended for anyone < 12 years of age.

  • What is the recommended primary course of COVID-19 vaccines for immunocompromised individuals?

    Severely immunocompromised individuals aged ≥ 6 months are recommended to receive a 3-dose primary course of COVID-19 vaccination with the third dose of vaccine being administered 8 weeks following the second dose.

    Age-appropriate mRNA vaccines (Spikevax (Moderna) or Comirnaty (Pfizer)) are recommended for immunocompromised individuals.

    Nuvaxovid (Novavax) may be used in those aged ≥ 12 years who received Nuvaxovid for their first 2 doses or in those with a contraindication to mRNA vaccination, however there is minimal efficacy data available on it’s use in this patient group. Those aged ≥ 18 years who received Vaxzevria (AstraZeneca) without any serious adverse event for their first two doses may choose to receive Vaxzevria as the third dose of their primary course, however alternate brands are recommended and preferred.

    NB: Individuals ≥ 12 years receiving Spikevax (Moderna) as their third primary dose should receive a full dose (100µg). This differs from the recommended Spikevax (Moderna) booster dose where only a half dose (50µg) is indicated.

    Following a 3-dose primary course of vaccination, severely immunocompromised individuals ≥ 12 years should receive a booster dose (4th dose) ≥ 3 months from completion of the primary course. An additional “winter” booster dose (5th dose) is recommended for those ≥ 16 years ≥ 4 months after receiving the first booster.

  • What is the primary COVID-19 vaccine schedule for children aged < 12 years?

    There are 2 vaccines registered for use in children:

    6 months-5 years Spikevax (Moderna) 25µ dose (blue cap, magenta vial border)

    *note 100mcg/ml formulation

    Primary schedule 2 doses, 8 weeks apart (can be reduced to 4 weeks in certain circumstances)
    Primary schedule for severely immunocompromised 3 doses, with the 3rd administered 2 months after the second
    5-11 years Comirnaty (Pfizer) 10µ dose (orange cap)
    Primary schedule 2 doses, 8 weeks apart (can be reduced to 3 weeks in certain circumstances)
    Primary schedule for severely immunocompromised 3 doses, with the 3rd dose administered 2 months after the second
    6-11 years Spikevax (Moderna) 50µ dose (blue cap, purple vial border)

    *note 200mcg/ml formulation

    Primary schedule 2 doses, 8 weeks apart (can be reduced to 4 weeks in certain circumstances)
    Primary schedule for severely immunocompromised 3 doses, with the 3rd administered 2 months after the second

    More information can be found at MVEC: COVID-19 vaccination in children and adolescents.

  • What are the recommendations for children who turn 12 years old prior to receiving their second dose of vaccine?

    Vaccine doses are recommended based on the age of the recipient at the time of vaccination. If a child previously received their first dose of COVID-19 vaccine as a paediatric dose/formulation and turned 12 before they were due for their second dose, the second dose should be the administered as a full adult dose dose/formulation.

    Delaying initial vaccination until a child turns 12 is not recommended.

  • What are the ABSOLUTE minimum and maximum intervals for each COVID-19 vaccine dose?

    ATAGI recommends that the absolute minimum interval between dose 1 and 2 of any COVID-19 vaccine is 14 days. In circumstances where a dose 2 has been administered earlier than 14 days after the first dose, that dose in considered invalid and must be repeated. A repeat dose can be administered 4-12 weeks following the invalid dose to complete the primary course.

    There is no maximum interval in which a primary course must be completed by before a vaccine course must be started again.

    Please refer to Australian Government Department of Health: Clinical recommendations for COVID-19 vaccines for more information.

  • Are COVID-19 vaccine brands that are available overseas recognised within Australia?

    In addition to the five COVID-19 vaccine brands with provisional registration in Australia (Comirnaty (Pfizer), Vaxzevria (AstraZeneca), Spikevax (Moderna), Nuvaxovid (Novavax) and COVID-19 Vaccine Janssen (Janssen-Cilag Pty Ltd)), the TGA also recognises the following COVID-19 vaccine brands as currently in use internationally:

    • Coronavac (Sinovac)
    • Covishield (AstraZeneca/Serum Institute of India).
    • BIBP-CorV (Sinopharm)
    • Covaxin  (Bharat Biotech)
    • Sputnik V (Gamaleya Research Institute).

    When making an assessment on the validity of vaccines, the TGA thoroughly reviews information relating to a vaccine’s efficacy and effectiveness to determine the impact of vaccination on severe disease as well as disease transmission.

    For more information please refer to MVEC: COVID-19- TGA recognised vaccines

  • What is the recommendation for individuals who have received dose 1 of a brand of COVID-19 vaccine that is not available in Australia?

    Individuals who have previously received a TGA-recognised first dose of COVID-19 vaccine that is not available in Australia can complete their vaccine course with any COVID-19 vaccine brand available in Australia. This second dose can be administered 4-12 weeks following the first dose. A longer interval will be accepted if this is not possible.

    A COVID-19 vaccine booster dose is then recommended for all age-eligible individuals ≥3 months following the completion of the primary course.

    For further information in Australia refer to ATAGI clinical advice on the use of a different COVID-19 vaccine as the second dose.

  • What is the recommendation for individuals who have received a COVID-19 vaccine(s) overseas that is not recognised in Australia?

    Individuals who have previously received a first dose or a course of COVID-19 vaccine/s using a brand that is not recognised in Australia should be re-vaccinated with a full course using a brand that is recognised by the TGA.

    The minimum interval between receiving the last dose of non-recognised vaccine and receiving the first dose of TGA recognised vaccine should be the same interval that is recommended between doses of the non-recognised vaccine course (commonly 3-6 weeks depending on the vaccine). A longer interval will be accepted if this is not possible. Once a TGA recognised COVID-19 vaccine course has been commenced, the recommended intervals between these doses should be adhered to.

    For further information on COVID-19 vaccines recognised in Australia refer to COVID-19: TGA recognised vaccines.

  • When should people who have previously tested positive for COVID-19 disease be vaccinated?

    COVID-19 vaccination should be deferred 3 months following COVID-19 infection in order to optimise protection.

    Recommended COVID-19 vaccine schedules should be completed after this time.

    For further information, refer to the Clinical recommendations for COVID-19 vaccines.

  • What are the vaccine recommendations for people who have contracted COVID-19 disease after receiving dose 1 of the vaccine but before dose 2?

    Where an individual has contracted COVID-19 disease between vaccine doses, it is recommended the next scheduled dose is deferred for a period of 3 months following infection.

    Recommended COVID-19 vaccine schedules should be completed after this time.

    For further information, refer to the Clinical recommendations for COVID-19 vaccines.

  • For patients who have tested to positive to COVID-19 disease and received monoclonal antibodies or convalescent plasma as part of their treatment, when is the ideal time for vaccination?

    Patients with a past history of COVID-19 infection, who received monoclonal antibodies or convalescent plasma as part of their treatment, should wait a minimum of 3 months before considering vaccination.

  • How long will it take to develop immunity once vaccinated?

    There is some evidence that one dose of Comirnaty (Pfizer) or Spikevax (Moderna) will provide partial protection after 12 days however this is likely to be short lived. Generally the time required following vaccination for the body to develop immunity will depend on the vaccine; this usually takes a number of weeks. Completing both doses of the 2 dose course is recommended.

  • I have had a recent live vaccine, can I have a COVID-19 vaccine?

    Generally speaking, COVID-19 vaccines can be co-administered on the same day as any other vaccine (including live-attenuated vaccines). The only exception to this, is the preference to separate COVID-19 vaccines from other vaccines by 7-14 days in children aged 6 months-5 years to limit the risk of adverse events such as fever.

  • Can I get a blood test to check my immune response?

    COVID-19 serology is not routinely available following vaccination and is not able to inform the decision to proceed with future doses. Due to the novel nature of SARS-CoV-2, a correlate of protection has not yet been established for COVID-19 in humans.

  • What is the recommended interval between COVID-19 vaccination and tuberculin skin testing (TST, Mantoux)?

    COVID-19 vaccination and TST can be performed on the same day provided they are administered in separate limbs.

  • Can patients diagnosed with multisystem inflammatory syndrome relating to COVID-19 infection receive COVID-19 vaccines?

    Yes COVID-19 vaccines can be administered in this patient group following a discussion with an immunisation specialist or cardiologist on the optimal timing of vaccination. It is recommended that individuals have complete heart recovery prior to use of COVID-19 mRNA vaccines.   

    Please refer to Victorian COVID-19 vaccination guidelines for more information.

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: Francesca Machingaifa (MVEC Education Nurse Coordinator)

Date: August 30, 2022

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.