Published: 3 June 2021

Publications

Spotlight on Comirnaty vaccine

Published: 3 June 2021
Prescriber Update 42(2): 16–17
June 2021

Introduction

Comirnaty vaccine, manufactured by Pfizer/BioNTech, is an mRNA vaccine indicated for the active immunisation against COVID-19 infection caused by SARS-CoV-2 in individuals aged 16 years and older.¹ The vaccine has provisional approval, granted under section 23 of the Medicines Act 1981.

Comirnaty is the first vaccine using mRNA technology to be used in New Zealand. The mRNA codes for the spike protein of the SARS-CoV-2 virus. The mRNA is contained within lipid nanoparticles to help protect it from damage and deliver it into the cell. The cell then manufactures the spike protein, which then stimulates the immune system.

The fragility of the mRNA means that the vaccine has particular storage requirements and needs careful handling during vaccine dilution and administration.

Efficacy

Efficacy was evaluated in study C459001 – a multicentre, multinational, phase 1/2/3 randomised placebo-controlled observer-blind trial.² Subjects received two doses of vaccine 21 days apart. Efficacy was calculated based on the number of cases of SARS-CoV-2 infection seven days after the second dose. At the time of Medsafe provisional approval, the median follow-up time for subjects in the study was two months. For the primary efficacy endpoint of symptomatic COVID-19 infection, data from 18,198 vaccinated subjects and 18,325 subjects given placebo resulted in a vaccine efficacy of 95 percent (95% credible interval: 90.3–97.6). The long-term efficacy remains to be elucidated. Follow-up of subjects in study C459001 is scheduled for completion in 2023.

Missing information

A number of conditions were placed on the provisional approval of Comirnaty vaccine to address missing information from the application. These conditions are published on the Medsafe website, in the Gazette notice (PDF 4 pages, 60 KB) and the Product/Application search entry.

In addition, the following have been identified in the Risk Management Plan as areas of missing information.

• Use in pregnancy and while breast feeding.
• Use in immunocompromised patients.
• Use in frail patients with co-morbidities (eg, chronic obstructive pulmonary disease [COPD], diabetes, chronic neurological disease, cardiovascular disorders).
• Use in patients with autoimmune or inflammatory disorders.
• Interaction with other vaccines.
• Long-term safety data.

Ongoing studies and collection of real-world safety data will help address these information gaps, and the data sheet will be updated as needed. See the Risk Management Plan for more details.

The Australasian Society of Clinical Immunology and Allergy have issued guidance on vaccination for patients with immunodeficiency or autoimmunity.

The Ministry of Health also publishes advice for the health sector.

Safety

In the clinical trial, the most frequently reported adverse reactions were injection site pain, fatigue, headache, myalgia, chills, arthralgia, pyrexia and injection site swelling.² These adverse reactions are often called reactogenic events. There was a slightly higher incidence of reactogenic events after the second dose compared to the first dose in the clinical trial.

The full list of adverse reactions can be found in the data sheet. Rare but important adverse reactions include anaphylaxis (see the Anaphylaxis article), hypersensitivity and acute peripheral facial paralysis.

The Australasian Society of Clinical Immunology and Allergy have issued guidance on allergy and COVID-19 vaccination.

The inclusion of acute peripheral facial paralysis was based on an imbalance of cases in the clinical trial: four cases in subjects receiving vaccine and none in subjects given placebo.

An overview of the reports to the Centre for Adverse Reactions Monitoring (CARM) describing adverse events following immunisation (AEFI) is published on the Medsafe website.

New Zealand’s COVID-19 Independent Safety Monitoring Board (CV-ISMB) is an independent expert advisory group on the safety of COVID-19 vaccines. The CV-ISMB meets regularly to review the available safety information, including AEFIs reported to CARM, and provides expert advice to CARM, Medsafe, the COVID-19 immunisation programme and the Ministry of Health.

Reporting

We have had a fantastic response from vaccinators and vaccinees reporting AEFI to CARM. Please continue to report any suspected AEFI for the Comirnaty vaccine.

References

1. Pfizer New Zealand Limited. 2021. Comirnaty New Zealand Data Sheet 22 March 2021. URL: medsafe.govt.nz/profs/Datasheet/c/comirnatyinj.pdf (accessed 8 April 2021).
2. Polack FP, Thomas SJ, Kitchen N, et al. 2020. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. New England Journal of Medicine 383(27): 2603–15. DOI: 10.1056/NEJMoa2034577 (accessed 8 April 2021).