MHRA has approved Zapomeran (Kostaive), an mRNA COVID-19 vaccine for adults aged 18+. Learn about its approval, clinical trial results, safety profile, and use.
Written By: Pharmacally Medical News Desk
On 2 January 2026, the United Kingdom’s Medicines and Healthcare Products Regulatory Agency (MHRA) granted approval for Zapomeran, marketed under the name Kostaive, as a new mRNA COVID-19 vaccine for adults aged 18 years and older. This decision expands the options available for COVID-19 immunization in the UK and comes as public health agencies continue efforts to manage the disease in the post-pandemic phase.
Regulatory Decision and Use
Zapomeran (Kostaive) was authorized under the MHRA’s International Recognition Procedure (IRP), with the European Medicines Agency (EMA) acting as the reference regulator for its assessment. Under this pathway, the MHRA can recognize evaluations by trusted international regulators while conducting its own review of safety and efficacy.
Julian Beach, Interim Executive Director of Healthcare Quality and Access at the MHRA, said: “Patient safety is our top priority. The approval of Zapomeran (Kostaive) provides an alternative vaccine for use in adults to prevent COVID-19 caused by SARS-CoV-2. As with all licensed medicines, we will continue to monitor its safety closely as it becomes more widely used.”
The vaccine is indicated for active immunization against COVID-19 caused by SARS-CoV-2 in adults aged 18 and over. It is administered as a single 0.5 mL booster dose by intramuscular injection into the upper arm.
Clinical Evidence
Clinical efficacy was assessed in the pivotal phase 3 trial ARCT-154-2301. In SARS-CoV-2-naïve adults receiving the primary vaccination series, Kostaive demonstrated 56.7% efficacy against symptomatic COVID-19 between 36 and 92 days after the first dose. This was based on 200 symptomatic cases among 7,762 participants in the vaccine group compared with 440 cases among 7,696 in the placebo group. Against severe disease, efficacy was 95.3% (2 cases in the vaccine group vs. 41 in the placebo group).
As a booster dose in individuals previously vaccinated with mRNA COVID-19 vaccines, Kostaive produced anti-spike antibody levels that were non-inferior to those elicited by Comirnaty (the Pfizer-BioNTech vaccine), supporting its use as a heterologous booster option.
Mechanism of Action
Zapomeran uses self-amplifying messenger RNA (sa-mRNA) technology. Similar to other mRNA vaccines, it delivers genetic instructions to the body’s cells to temporarily produce the SARS-CoV-2 spike protein, which triggers an immune response. The self-amplifying aspect means the mRNA also encodes a replicase enzyme, enabling the production of additional copies of the antigen. This can enhance immune stimulation while potentially allowing lower doses.
Once injected, the sa-mRNA in lipid nanoparticles enters cells, where it directs production of the spike protein. The immune system recognizes this protein as foreign and mounts a defense by producing antibodies and activating T cells. If a vaccinated individual later encounters the virus, their immune system is better prepared to respond and prevent serious illness.
Safety and Side Effects
In the MHRA’s announcement, officials highlighted ongoing safety monitoring as the vaccine is rolled out more widely. Common side effects reported with Kostaive are similar to those seen with other COVID-19 vaccines. These include:
- Pain or tenderness at the injection site
- Tiredness
- Chills and fever
- Headache and dizziness
- Muscle and joint pain
Most of these reactions are mild and resolve within a few days of vaccination.
Health authorities encourage anyone who suspects a side effect to consult a healthcare professional and report their experience through the MHRA Yellow Card scheme, a system used to monitor the safety of medicines in real time.
Context and Implications
Zapomeran’s approval in the UK follows earlier authorizations in other regions, including the European Union and Japan. It represents one of the newer vaccine technologies using sa-mRNA, which is distinct from conventional mRNA platforms by its self-amplifying capabilities.
The availability of Kostaive adds another choice for adult COVID-19 vaccination, supporting public health strategies to maintain immunity in the population, particularly as SARS-CoV-2 continues to evolve and circulate. The MHRA has reiterated its commitment to close safety and effectiveness surveillance as the vaccine is deployed.
Summary
MHRA approved Zapomeran (Kostaive) on 2 January 2026 for adults aged 18+ in the UK.
It uses self-amplifying mRNA technology to stimulate immunity against SARS-CoV-2.
The vaccine is given as a single intramuscular booster dose.
Common side effects are generally mild and temporary.
Ongoing monitoring through systems like the Yellow Card scheme will track safety after approval.
References
MHRA approves Zapomeran (Kostaive) mRNA COVID-19 vaccine, 02 January 2025, https://www.gov.uk/government/news/mhra-approves-zapomeran-kostaive-mrna-covid-19-vaccine
Kostaiv (Zapomeran) Europan Medicine Agency What benefits of Kostaiv have been shown in studies? https://www.ema.europa.eu/en/medicines/human/EPAR/kostaive#product-details