In short
SARS-COV-2 JN.1 mRNA is an mRNA molecule with instructions for producing a protein from the Omicron JN.1 subvariant of SARS-CoV-2, the virus that causes COVID-19. It is the active component of the adapted Spikevax JN.1 vaccine authorised in the EU. One authorised trial, a Phase 3 study with 410,000 participants, compares a combined influenza/COVID-19 vaccine against separate injections of Spikevax JN.1 and a high-dose influenza vaccine in adults aged 65 and older.
Key points
- SARS-COV-2 JN.1 mRNA is the active component of Spikevax JN.1, an adapted COVID-19 vaccine authorised in the EU.
- It carries instructions for making a spike protein from the Omicron JN.1 subvariant of SARS-CoV-2.
- One registered trial, a Phase 3 study with 410,000 participants, is authorised in the EU.
- The trial compares a combined influenza/COVID-19 vaccine against separate injections in adults aged 65 and older.
- The main measures are medically attended influenza or COVID-19 and hospitalisation from either infection.
What is SARS-COV-2 JN.1 mRNA?
SARS-COV-2 JN.1 mRNA is a molecule of messenger RNA (mRNA) with instructions for producing a protein from the Omicron JN.1 subvariant of SARS-CoV-2, the virus that causes COVID-19. It is the active component of Spikevax JN.1, one of five adapted versions of the Spikevax vaccine authorised in the European Union. The adapted vaccines were developed because SARS-CoV-2 keeps evolving, and updating the mRNA sequence helps maintain protection against COVID-19. Spikevax and its adapted vaccines do not contain the virus itself and cannot cause COVID-19.
How does SARS-COV-2 JN.1 mRNA work?
The mRNA carries instructions that teach cells in the body to produce a protein from the Omicron JN.1 subvariant of SARS-CoV-2. This protein is recognised by the immune system, which then builds a defence against the virus. When a vaccinated person later encounters SARS-CoV-2, the immune system is already prepared to respond. The vaccine does not contain the virus itself, so it cannot cause COVID-19.
Which conditions is SARS-COV-2 JN.1 mRNA used or studied for?
The authorised use of Spikevax JN.1 is the prevention of COVID-19 in people from the age of 6 months. In the registered trial, the substance is studied as part of a combined vaccine for the prevention of two infections:
- SARS-CoV-2 infection — the infection caused by the coronavirus that leads to COVID-19.
- Influenza infection — the respiratory infection caused by influenza viruses, which the combined vaccine also targets.
How is SARS-COV-2 JN.1 mRNA given?
Spikevax JN.1 is given as an injection into the muscle, usually of the upper arm. In the registered trial, the substance appears as Spikevax JN.1 50 micrograms dispersion for injection in a pre-filled syringe, given by intramuscular injection. The originally authorised Spikevax is given as two injections 28 days apart in people from the age of 6 months, with booster doses available for adults and children.
What do the clinical trials show?
One trial is registered in the EU Clinical Trials Information System for this substance. It is a Phase 3, pragmatic, randomised trial with a planned enrolment of 410,000 participants, currently authorised. The trial evaluates the effectiveness of a combined influenza/COVID-19 vaccine (mCombriax, also known as mRNA-1083) compared with same-day co-administration of the active comparators: high-dose influenza vaccine (Efluelda) and mRNA-1273 (Spikevax).
The study population is adults aged 65 years and older. The primary endpoints are the occurrence of medically attended influenza and/or COVID-19, and influenza and/or COVID-19 hospitalisation. The trial is interventional, meaning participants receive one of the vaccine regimens and are followed over time.
What side effects are known?
The available source does not list specific side effects for SARS-COV-2 JN.1 mRNA. The European Medicines Agency overview states that Spikevax is authorised because its benefits outweigh its risks, but does not detail individual side effects in the provided material.