Addendum: Updates in Dosage for Primary Series and Booster
21 November 2023 | Vaccinations | MOH Cir 76A/2023
Summary
1. Background
Addendum to Circular 76/2023. MOH updates dosage of Moderna/Spikevax XBB.1.5 vaccine for ages 6-11 years, standardising to 25 mcg per dose for both primary series and booster/additional doses. Change from prior 50 mcg dosage based on EC19V recommendations considering immune response adequacy and population hybrid immunity.
2. Dosage Update: 6-11 Years Age Group
- Previous Dosage: 50 mcg per dose (as per Moderna/Spikevax initial authorisation)
- NEW Standardised Dosage: 25 mcg per dose
- Applies To:
- Primary series (2 doses)
- Booster doses
- Additional doses
- Effective: As per EC19V recommendation; apply immediately to new vaccinations
- Formulation: Uses standard Moderna vial with appropriate volume per dose
3. Rationale for Dosage Reduction
- Immune Response: Evidence shows 25 mcg sufficient to produce good immune protection for 6-11 age group
- Population Immunity: Many children in this age group already exposed to COVID-19 infection
- Hybrid Immunity: High level of population hybrid immunity in this cohort (vaccination + prior infection)
- Safety-Benefit Profile: Lower dose maintains protection while reducing risk of common adverse events (myocarditis risk minimal in this age group but further reduction beneficial)
4. Practical Administration
- Volume Calculation: 25 mcg requires precise dosing per product insert
- Documentation: Clearly document "25 mcg" (not standard adult 50 mcg) in records
- Cold Chain: Standard Moderna storage/stability unchanged
- Vaccination Records: Ensure records show correct dose administered for future booster scheduling
5. Comparison with Pfizer Dosage
- Pfizer/Comirnaty: Uses different dose (10 mcg) for similar age group; not interchangeable
- Moderna 25 mcg ≠ Pfizer 10 mcg: Different formulations; switching not recommended
- Consistency: Once vaccine platform chosen, maintain for consistency in care
6. Action for Your Practice
- Update Protocols: Revise all Moderna 6-11 year protocols from 50 mcg to 25 mcg
- Staff Training: Ensure all staff administer correct 25 mcg dose
- Vaccine Stock: Continue using Moderna 50 mcg vials; adjust volume for 25 mcg administration
- Patient Records: Document "Moderna 25 mcg" clearly in vaccination records
- Catch-Up: For children previously receiving 50 mcg: discuss with patient/parent; additional doses as per ECI guidance for booster schedule
- Scheduling: Continue booster timing per current recommendations; next dose at standardised 25 mcg
- Communication: Inform parents this is dose optimisation, not vaccine change
7. Key Clinical Points
- Change applies only to ages 6-11 for Moderna
- Primary series children already partially vaccinated: continue with 25 mcg for remaining doses
- No safety concerns; change based on immunogenicity data
- Improves benefit-risk profile for this age group
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𝟭. 𝗕𝗮𝗰𝗸𝗴𝗿𝗼𝘂𝗻𝗱
Addendum to Circular 76/2023. MOH updates dosage of Moderna/Spikevax XBB.1.5 vaccine for ages 6-11 years, standardising to 25 mcg per dose for both primary series and booster/additional doses. Change from prior 50 mcg dosage based on EC19V recommendations considering immune response adequacy and population hybrid immunity.
𝟮. 𝗗𝗼𝘀𝗮𝗴𝗲 𝗨𝗽𝗱𝗮𝘁𝗲: 𝟲-𝟭𝟭 𝗬𝗲𝗮𝗿𝘀 𝗔𝗴𝗲 𝗚𝗿𝗼𝘂𝗽
• Previous Dosage: 50 mcg per dose (as per Moderna/Spikevax initial authorisation) • NEW Standardised Dosage: 25 mcg per dose • Applies To: • Primary series (2 doses) • Booster doses • Additional doses • Effective: As per EC19V recommendation; apply immediately to new vaccinations • Formulation: Uses standard Moderna vial with appropriate volume per...
𝟯. 𝗥𝗮𝘁𝗶𝗼𝗻𝗮𝗹𝗲 𝗳𝗼𝗿 𝗗𝗼𝘀𝗮𝗴𝗲 𝗥𝗲𝗱𝘂𝗰𝘁𝗶𝗼𝗻
• Immune Response: Evidence shows 25 mcg sufficient to produce good immune protection for 6-11 age group • Population Immunity: Many children in this age group already exposed to COVID-19 infection • Hybrid Immunity: High level of population hybrid immunity in this cohort (vaccination + prior infection) • Safety-Benefit Profile: Lower dose maintains protection while...
𝟰. 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗮𝗹 𝗔𝗱𝗺𝗶𝗻𝗶𝘀𝘁𝗿𝗮𝘁𝗶𝗼𝗻
• Volume Calculation: 25 mcg requires precise dosing per product insert • Documentation: Clearly document "25 mcg" (not standard adult 50 mcg) in records • Cold Chain: Standard Moderna storage/stability unchanged • Vaccination Records: Ensure records show correct dose administered for future booster scheduling
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