A Study Testing mRNA-1273 Vaccine Safety and Effectiveness Against Severe COVID-19 in Adults Aged 50-64 Years Without Risk Factors

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What is this study about?

This study is looking at SARS-CoV-2 infection, which is the virus that causes COVID-19. The study will use a vaccine called Spikevax, which contains elasomeran, also known by its code name mRNA-1273. This is a messenger RNA vaccine that teaches the body to recognize and fight against the virus. The vaccine will be given as a single injection into the muscle. The study will involve adults between 50 and 64 years of age who do not have risk factors that would make COVID-19 more severe for them.

The purpose of this study is to find out how well the vaccine works in reducing the risk of COVID-19 that requires medical attention compared to not receiving the vaccine. The study will also look at how safe the vaccine is in this age group. This is a randomized trial, which means that participants will be assigned by chance to either receive the vaccine or not receive it. The researchers will then compare the two groups to see if there are differences in how many people develop COVID-19 that needs medical care.

During the study, researchers will track whether participants develop COVID-19 by looking at positive test results or hospital admissions related to the infection. They will also look at other outcomes such as hospitalizations for breathing problems related to COVID-19, heart and breathing problems, and deaths. The study will follow participants over time to collect this information and determine how effective the vaccine is in preventing illness in this specific age group without other health conditions that put them at higher risk.

1 Enrollment and vaccination

After joining the study, you will be randomly assigned to one of two groups. One group will receive the vaccine, and the other group will not receive the vaccine at this time.

If you are assigned to the vaccine group, you will receive Spikevax 50 micrograms vaccine. This is an mRNA vaccine that helps protect against COVID-19.

The vaccine will be given as a single injection into your muscle, typically in your upper arm.

The vaccine comes in a pre-filled syringe and is administered by a healthcare professional.

2 Follow-up period

After receiving the vaccine or being assigned to the non-vaccine group, you will be followed through health registries.

The study will track whether you develop COVID-19 that requires medical attention. This is defined as either a positive PCR test (a laboratory test that detects the virus) for SARS-CoV-2 or hospitalization for COVID-19-related breathing problems.

The study will also monitor other health outcomes, including hospitalizations related to COVID-19, breathing problems, heart and lung issues, and overall health status.

Your participation in the follow-up period will continue until the study ends, which is estimated to be in August 2026.

3 Data collection

Information about your health will be collected from national health registries throughout the study period.

This includes records of any COVID-19 diagnoses, hospital admissions, and other relevant health events.

No additional visits or procedures beyond the initial vaccination are required from you during the study.

Who Can Join the Study?

To join this study, you must meet these requirements:

You must be between 50 and 64 years old
You must sign and date an informed consent form, which is a document that explains the study and confirms you agree to take part

Who Cannot Join the Study?

The study does not list specific reasons why you cannot participate
General exclusion criteria will be determined by the study doctors during screening
You should discuss your medical history and current health status with the study team to find out if you can take part

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

No sites found in this category

Other Sites

Site Name	City	Country	Status
Gentofte Hospital	Hellerup	Denmark
Dlioyb Lsavtmp Vahmhwwbriel Sckdkew	Soeborg	Denmark

Trial status

Country	Status	Recruitment Start
Denmark	Not recruiting	30.11.2025

Trial locations

Investigated drugs:

Elasomeran

mRNA-1273 is a vaccine that helps protect against COVID-19. This vaccine works by teaching your body to recognize and fight the virus that causes COVID-19. In this trial, researchers are testing a version of this vaccine that has been updated to work against different variants (changed forms) of the COVID-19 virus. The vaccine is being studied to see how well it prevents COVID-19 infections that require medical attention in adults between 50 and 64 years old who do not have health conditions that put them at higher risk for severe COVID-19.

SARS-CoV-2 Infection – SARS-CoV-2 infection is a viral illness caused by the severe acute respiratory syndrome coronavirus 2. The virus primarily spreads through respiratory droplets when an infected person coughs, sneezes, or talks. After entering the body, the virus attaches to cells in the respiratory tract and begins to multiply. The infection can affect various organs, though it most commonly impacts the lungs and breathing system. Some people experience mild symptoms such as fever, cough, and fatigue, while others may develop more severe breathing difficulties. The disease can progress from initial mild symptoms to more serious respiratory problems requiring medical attention.

Trial ID:

2025-523841-82-00

Protocol code:

DAN-COVID

Trial Phase:

Therapeutic confirmatory (Phase III)

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A Study Testing mRNA-1273 Vaccine Safety and Effectiveness Against Severe COVID-19 in Adults Aged 50-64 Years Without Risk Factors

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?