Dosing information COVID-19 primary vaccination

Marianne Eve, Medicines Information Pharmacist, Midlands and East Medicines Advice Service (East site)Published Last updated See all updates

Dose scheduling, actions when the intervals are longer than or less than recommended, and use of alternative brands for second doses

Dose scheduling

UK Health Security Agency (UKHSA) Immunisation Against Infectious Disease (the Green Book) states that there is evidence of better immune response and/or protection where longer intervals between doses are used, however it is acknowledged that this is different to the MHRA licensed dosing-interval for each vaccine.

Adults

The Joint Committee for Vaccines and Immunisation (JCVI) is recommending an interval of 8 weeks between doses of all the available COVID-19 vaccines where a two-dose primary schedule is used. Operationally, this consistent interval should be used for all two dose vaccines to avoid confusion and simplify booking, and will help to ensure a good balance between achieving rapid and long-lasting protection.

MHRA advice

The MHRA Information for Healthcare Professionals for individual vaccines recommends a primary vaccination schedule:

  • Pfizer-BioNTech the dose is 30 micrograms contained in 0.3ml of the diluted vaccine as a series of two doses at least 21 days apart.
  • AstraZeneca the dose is 0.5ml as a series of two doses between 4 and 12 weeks apart.
  • Moderna the dose is 100 micrograms in 0.5ml as a series of two doses 28 days apart.

Children and young people at high risk

UK Health Security Agency (UKHSA) Immunisation Against Infectious Disease (the Green Book) recommends an interval of 8 weeks between doses of all the available COVID-19 vaccines where a two-dose primary schedule is used.

Children aged 5 to 11 years who are at high risk, or who expect to share living accommodation on most days with individuals of any age who are immunosuppressed, should receive two doses of the paediatric dose of Pfizer BioNTech vaccine at an interval of at least eight weeks.

MHRA advice

The MHRA Information for Healthcare Professionals for individual vaccines recommends a primary vaccination schedule:

Children aged 5-11
  • Pfizer-BioNTech the dose is 10 micrograms contained in 0.2ml of the diluted vaccine as a series of two doses at least 21 days apart.
Children and young people aged 12 years and over
  • Pfizer-BioNTech the dose is 30 micrograms contained in 0.3ml of the diluted vaccine as a series of two doses at least 21 days apart.
  • Moderna the dose is 100 micrograms in 0.5ml as a series of two doses 28 days apart.

Children and young people not in a high risk group

UK Health Security Agency (UKHSA) Immunisation Against Infectious Disease (the Green Book) states that for those aged 16 to 18 who are not in a high risk group a 12 week interval is preferred. The interval may be shortened to eight weeks in periods of high incidence or where there is concern about vaccine effectiveness (for example a new variant).

Children and young people aged 12-15 years should receive two doses of the COVID-19 vaccine at an interval of 12 weeks. This interval may be shortened to eight weeks in periods of high incidence or where there is concern about vaccine effectiveness (for example a new variant).

MHRA advice

The MHRA Information for Healthcare Professionals for individual vaccines recommends a primary vaccination schedule:

Children aged 5-11
  • Pfizer-BioNTech the dose is 10 micrograms contained in 0.2ml of the diluted vaccine as a series of two doses at least 21 days apart.
Children and young people aged 12 years and over
  • Pfizer-BioNTech the dose is 30 micrograms contained in 0.3ml of the diluted vaccine as a series of two doses at least 21 days apart.
  • Moderna the dose is 100 micrograms in 0.5ml as a series of two doses 28 days apart.

Third primary dose for immunosuppressed patients

Patients who are immunosuppressed due to underlying health conditions or medical treatment may not mount a full immune response to primary COVID-19 vaccination.  The Green Book suggests that these patients should be offered a third primary vaccination.

Individuals whose immunosuppression started at least 2 weeks after the second dose of vaccine do not require an additional dose.

The third dose should be given ideally at least 8 weeks after the second dose. The decision on timing of the third dose should be taken by the specialist involved in the care of the patient. In general, vaccines administered during periods of minimum immunosuppression are more likely to generate better responses.

The Green Book provides the criteria for patients who are eligible for a third primary vaccine dose.

MHRA advice

The MHRA Information for Healthcare Professionals for individual vaccines allows a third primary vaccination dose for individuals who are severely immunocompromised:

  • Pfizer-BioNTech a third dose of 30 micrograms contained in 0.3ml may be given at least 28 days after the second dose to individuals who are severely immunocompromised.
  • Moderna  a third dose of 100 micrograms in 0.5ml may be given at least 28 days after the second dose to individuals who are severely immunocompromised.

Using COVID-19 vaccines in patients taking immunosuppressive medicines contains further information.

A number of actions are necessary where the interval between doses is longer than recommended.

UK Health Security Agency (UKHSA) advise that if the interval between the first dose and second dose is longer than recommended, the second dose should still be given (preferably using the same vaccine as was given for the first dose). The course does not need to be restarted.

If the interval between the first dose and the second dose is longer than recommended the Patient Group Directions (PGDs) and National Protocols for each COVID-19 vaccine may be used to administer the second dose of a vaccine.

A number of vaccine dependent actions are necessary where the interval between doses is shorter than recommended.

Dose has been given less than 19 days after the first dose

UK Health Security Agency (UKHSA) advise that the second dose should be discounted. Another dose (i.e. a third dose) should be given, at least 21 days after the discounted second dose (the dose that was given too early).

The ‘third dose’ cannot be administered under the Patient Group Direction (PGD) or National Protocol for this vaccine. A Prescription or Patient Specific Direction (PSD) is required.

Dose has been given less than 28 days but at least 21 days after the first dose

UK Health Security Agency (UKHSA) advise that the dose does not need to be repeated.

Dose has been given less than 21 days after the first dose

UK Health Security Agency (UKHSA) advise that the second dose should be discounted. Another dose (i.e. a third dose) should be given, at least 28 days after the discounted second dose (the dose that was given too early).

The ‘third dose’ cannot be administered under a Patient Group Direction (PGD) or National Protocol for this vaccine. A prescription or Patient Specific Direction (PSD) is required.

Using a different brand for the second dose

The UK Health Security Agency (UKHSA) Immunisation Against Infectious Disease (the Green Book) states that if the course is interrupted or delayed, it should be resumed using the same vaccine where possible.

There is accumulating evidence that supports interchanging between vaccines for the primary schedule, and these are now recognised by the European Medicines Agency. However, rates of side effects in those who receive a different vaccine for their second dose are higher compared to those who received the same vaccine for both doses.

Vaccine brand unavailable

There are various reason why the same brand of vaccine may not be available (e.g. the individual attended at a different site or the site is using a different vaccine on a particular day).

UK Health Security Agency (UKHSA) advise that when the same vaccine is not available or suitable, or if the first product received is unknown or unavailable, one dose of the locally available product should be given to complete the primary course so long as it is suitable for the age of the patient and is not contraindicated.

In these instances the Patient Group Directions (PGDs) and National protocols for each COVID-19 vaccine may be used to administer the second dose where the brand differs from the first dose.

Vaccine administered overseas

Overseas vaccine is available in UK

UK Health Security Agency (UKHSA) advise that for a person who has received a first dose of COVID-19 vaccine overseas that is available in the UK, they should receive the same vaccine for their second dose. They must meet UK eligibility criteria, as detailed in the Joint Committee on Vaccinations and Immunisations (JCVI) guidance. The Patient Group Directions (PGDs) and National protocols for each COVID-19 vaccine may be used in this circumstance.

Overseas vaccines is not available in UK

UK Health Security Agency (UKHSA) advise that for a person who has received a first dose of COVID-19 vaccines overseas that is not available in the UK, then the most similar alternative should be offered. The Patient Group Directions (PGDs) and National protocols for each COVID-19 vaccine may be used in this circumstance.

Adverse or allergic reactions

UK Health Security Agency (UKHSA) advise that those patients who experienced severe adverse allergic reactions or anaphylaxis reactions with the first dose of one brand of vaccine, may be offered another brand of vaccine if advised by an allergy specialist.  Individuals who experience a clotting episode with concomitant thrombocytopenia following the first dose of AstraZeneca vaccine may be offered another brand of vaccine.

In these instances the choice of vaccine would need to be assessed on an individual basis after review by an appropriate clinician and a prescription or Patient Specific Direction (PSD) is required.  It would not be appropriate to use the Patient Group Directions (PGDs) and National protocols.

Suitability for COVID-19 vaccination based on prior allergy or current dietary practices contains further information.

Individuals in clinical trials

UK Health Security Agency (UKHSA) advise that individuals who are participating in a clinical trial of COVID-19 vaccines who present for vaccination should be referred back to the investigators. Eligible persons who are enrolled in vaccine trials should then be provided with written advice on whether they can be safely vaccinated in the routine programme, and when.

In these instances the choice of vaccine would need to be assessed on an individual basis after review by an appropriate clinician and a prescription or Patient Specific Direction (PSD) is required.  It would not be appropriate to use the Patient Group Directions (PGDs) and National protocols.

Information on booster vaccination

Dosing information for COVID-19 booster vaccination

Guidance on eligibility of individuals to receive a reinforcing dose of COVID-19 vaccine, along with the recommended choice of vaccine

Use in conjunction with other material

This page should be read in conjunction with other material covering the legal mechanisms for the administration of COVID-19 vaccines.

The legal mechanisms available for giving COVID-19 vaccines and their application

A summary of the different legal mechanisms available, a priority order for the options, and advice on their application to different professional groups.

Change history

  1. Information on using a different brand for second dose has been updated to reflect new evidence in line with updates to Public Health England’s Immunisation Against Infectious Disease (The Green book). This includes removing advice for housebound individuals as this is no longer applicable. Replaced references from PHE to UKSHA in relation to the Public Health England’s Immunisation Against Infectious Disease (The Green book).
  1. Dosing information for children aged 5-11 years added
  1. Information on dose scheduling for children and young people updated. Primary vaccination dose information added for all vaccines.
  1. Information on third primary COVID-19 vaccine dose for immunosuppressed patients and children and young people added
  1. Page title amended to clarify that this page covers primary vaccination only and information on third primary dose of vaccination for individuals who were severely immunosuppressed added
  1. Dosing interval advice updated in line with updates to Public Health England’s Immunisation Against Infectious Disease (The Green book) and NHS England advice related to second dose intervals being brought forward from 12 weeks to 8 weeks.
  1. Minor heading title changes
  1. Published