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COVID-19 vaccinations: reconstitution and drawing up

The Pfizer/BioNTech COVID-19 vaccine is now being offered more widely in those aged under 40 years. But are you up to date on the reconstitution and drawing up technique?

Unplanned learning

One of the biggest differentiators with the Pfizer/BioNTech vaccine is that it requires reconstitution prior to administration, unlike the Oxford/AstraZeneca and Moderna vaccines. While many pharmacists will be experienced in delivering vaccines, such as travel vaccinations, they might not be as familiar with the reconstitution process.(1)

Training

Specific training requirements are clear in the guidance from Public Health England and are explored in detail in the COVID-19 Vaccinator Competency Assessment Tool, which requires all vaccinators to be trained in the dilution and drawing up of the COVID-19 vaccines.(2) Although reconstitution may previously have been covered in vaccination training courses, this is a bespoke technique and multi-dose drawing up will be for many pharmacists a new skill to learn.

Reconstituting

Reconstituted vaccines have the potential to become contaminated by bacteria entering the vial from the outside, especially if poor technique is used. For this reason, opened vials of reconstituted vaccines must be kept within the designated temperature specified by the manufacturer and must be discarded at the end of the immunisation session or within six hours of opening, whichever comes first.(3) It is therefore important not to prepare the vaccine too far in advance or you risk failing to use all doses (ie if patients do not turn up).

Dilution and reconstitution of the Pfizer/BioNTech vaccine

The Pfizer/BioNTech vaccine is supplied in packs of 195 vials, with each vial containing six doses of 0.3mL. It is supplied with a plastic 2mL ampoule of diluent (0.9% sodium chloride). Each ampoule is single use, with 1.8mL of the diluent required for drawing up, so any remaining diluent should be discarded. There are no special storage requirements for the diluent - it can be stored in dry storage away from direct sunlight. Only the diluent as stated from manufacturer’s guidance should be used, as diluents are not interchangeable.(1)

Dilute the Pfizer/BioNTech vaccine using an aseptic technique as follows:(4,5)

  • Clean hands with alcohol-based gel or soap and water
  • Prior to dilution, when the thawed vial is at room temperature, gently invert 10 times. Do not shake
  • Check expiry and date and appearance of the vial
  • Clean vial stopper with alcohol swab and allow to air dry (usually 30 seconds)
  • Draw up 1.8mL of sodium chloride 0.9% solution for injection using a 21G needle. Do not use any other type of diluent
  • Add diluent to vial - ensure the needle is positioned above the fluid line and touching the side of the glass ampoule, then slowly add the diluent to prevent any frothing. To equalise the pressure, withdraw 1.8mL of air into the empty diluent syringe before removing the needle from the vial
  • Invert diluted solution 10 times. Do not shake
  • Label diluted vial with dilution time and date

Once the vaccine has been diluted, it should be inspected to ensure it is not discoloured or does not have any visible particles. The Pfizer/BioNTech vaccine is designed to be an off-white colour with no particles visible. If there is discolouration or particles are present, the solution should be discarded. Once it has been mixed, it must be stored between 2°C and 25°C and used within six hours following dilution.(1,6)

Dose-sparing syringes/needles

To extract six doses from the vial, it is recommended to use dose-sparing syringes/needles. If standard syringes and needles are used, there may not be sufficient volume to extract a sixth dose from a single vial. However, if the sixth and final dose falls short of the complete volume required (0.3mL), discard this quantity because the vaccine cannot be mixed with that prepared from another vial.(4)

Multi-dose draw

One of the main differences between COVID-19 vaccinations and other vaccinations commonly used within community pharmacy is the use of multi-dose vials rather than single dose vials. You must not enter the bung through a previous injection site on a multi-dose vial because this will lead to particles being added to the vaccine. Therefore, you must use the bung as though it is a clockface. Go around the edge of the bung like a clockface, starting at 12 and then working round to 1,2, 3 etc, or you may prefer to do 12, 3, 6, 9 then in between. It is recommended that you use the labelling on the vial to indicate your 12 o’clock position. The 12 o’clock injection site should run parallel to the edge of the barcode label on the vaccine. Then follow around the bung as 1 o’clock, 2 o’clock etc or if you prefer more distance between injection site then follow around the bung clockface as 2 o’clock, 4 o’clock, etc.

Once the dose is drawn up, it should be administered immediately.(3)

Drawing up

For all COVID-19 vaccines, before drawing up, hands should be cleaned with alcohol-based gel or soap and water. It is important to clearly label multi-dose vials with date and time of expiry (six hours from time of first puncture). Vaccines should not be used if the time of first puncture was more than six hours previously.(6)

Pfizer/BioNTech vaccine

Vaccine dose preparation:

  • If the dose has previously been reconstituted, check the time is within the last six hours
  • Clean the bung with an alcohol wipe and leave to dry for 30 seconds. This should be completed before the draw of each of the 6 doses.
  • You can obtain six doses of 0.3mL from a reconstituted vial.
  • To equalise the pressure within the vial, you must add 0.3mL of air (1mL dose-sparing syringe with a 23G needle) prior to drawing up 0.3mL of the vaccine. Before removing the needle from the bung, ensure you have drawn the correct dose.
  • The same needle used for draw should be used to administer the vaccine.
  • Any air bubbles should be removed when drawing up before removing the needle from the vial to avoid losing any of the dose.

Pfizer/BioNTech has also produced a video showing how to reconstitute and prepare the vaccine.

Moderna vaccine

The Moderna vaccine does not require reconstitution. The solution should be white to off-white and may contain white or translucent product-related particulates. You can obtain 10 doses of 0.5mL from a 5mL vial.

Vaccine dose preparation:

  • Gently swirl the vial between each withdrawal but do not shake the vial
  • Clean the bung with an alcohol wipe and leave to dry for 30 seconds. This should be completed before the draw of each of the 10 doses.
  • A 1mL dose-sparing syringe with a 23G needle should be used to withdraw 0.5mL for each vaccination.
  • When drawing up, any air bubbles should be removed before removing the needle from the vial to avoid losing any of the dose.

Once the vial has been punctured, it should be used as soon as possible. If it is not used immediately, it must be stored between +2°C to +25°C and used within a six-hour period.(6)

Oxford/AstraZeneca vaccine

The Oxford/AstraZeneca vaccine does not require reconstitution. The solution should be colourless to slightly brown, clear to slightly opaque and free of particles.

This vaccine is provided as either 80 dose packs (ten 4mL vials, with at least eight doses per vial) or 100 dose packs (ten 5mL vials with at least 10 doses per vial). It is important to check how many doses are in the vial being used so vaccines are not wasted. After withdrawing eight or 10 doses, it may be possible to withdraw one full additional 0.5mL dose. If a full 0.5mL cannot be withdrawn, the contents should be discarded.

Vaccine dose preparation:

  • Gently swirl the vial between each withdrawal. Do not shake the vial
  • Clean the bung with an alcohol wipe and leave to dry for 30 seconds. This should be completed before the draw of each of the 8 or 10 doses
  • A 1mL dose-sparing syringe with a 23G or 25G needle should be used to withdraw 0.5mL for each vaccination.
  • When drawing up, any air bubbles should be removed before removing the needle from the vial to avoid losing any of the dose.

Once the vial has been punctured, it should be used as soon as possible. If it is not used immediately, it must be stored between +2°C to +25°C and used within a six-hour period.(6)

Air bubbles

Any air bubbles drawn up with a vaccine dose should be dealt with prior to removing the needle from the vial, as this will prevent another injection site into the bung and suboptimal vaccine administration.(6)

To remove an air bubble, slowly reinject the dose you have just drawn. Ensure your needle tip is not located within an air bubble within the vial. If it is, gently move the needle tip so it comes away from the air bubble, then redraw until you do not have an air bubble.

Morbidly obese patients

Separate 38mm length needles and syringes should be used for morbidly obese patients to ensure the vaccine can be injected into the muscle.(6)

For more information on reconstitution and drawing up see the Greenbook chapter 14a and Public Health England: COVID-19 vaccination programme information for healthcare practitioners.

References
  1. Public Health England (2021) Green Book 14a: COVID-19
  2. Public Health England (2021) COVID-19 vaccinator competency assessment tool
  3. World Health Organisation (2015) WHO guidance note: vaccine diluents
  4. Gov.UK (2010) National protocol for COVID-19 mRNA vaccine BNT162b2 (Pfizer/BioNTech)
  5. Electronic medicines compendium (2021) Summary of product characteristics: COVID-19 Vaccine (Temporary Authorisation – Review Product Information tab before reading) BNT162b2 RNA
  6. Gov.UK (2021) COVID-19 vaccination: information for healthcare practitioners
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