Seasonal influenza, also known as seasonal flu, is a respiratory illness caused by the influenza virus. This virus infects the lungs and breathing passages and is easily spread from person to person. Every year, seasonal flu causes 3 to 5 million cases of severe illness and up to 650,000 deaths worldwide.

COVID-19 is a respiratory illness caused by the SARS-CoV-2 virus. Common symptoms are similar to the flu and include fever, cough, and tiredness. More serious symptoms include difficulty breathing and loss of speech or mobility. COVID-19 was first identified in December 2019. As of May 2024, there have been more than 775 million reported COVID-19 cases worldwide.

Have received an investigational vaccine for seasonal flu or COVID-19 in another trial within the past year

Be pregnant or planning on becoming pregnant for at least 3 months following the injection visit 

Have received a flu vaccine in the previous season (since September 2023)

Participation in the Duo P201 Trial will last approximately 7 months and includes up to 4 in-person visits to a trial site and up to 2 safety phone calls.

You will be randomly assigned, like flipping a coin, to receive 1 of the 4 different batches (mRNA-1083 Lot A, mRNA-1083 Lot B, mRNA-1083 Lot C, mRNA-1083 Lot D) of the investigational combination vaccine, mRNA-1083. Each lot has different specific features.

Each participant will be given 1 injection in the upper arm.

Participants will be asked to use an eDiary app on their smartphone (or a provided device) to report any side effects they might experience every day for 7 days, starting on and including the day of injection.

Insurance is not needed to participate, and qualified participants will receive payment for their trial-related time and travel.

The Duo P201 Trial will evaluate the safety and immune response of 4 batches of an investigational combination vaccine, called mRNA-1083, aimed at preventing both seasonal flu and COVID-19 infections in adults 50 to 64 years of age.

Seasonal flu and COVID-19 are respiratory illnesses; seasonal flu is caused by the influenza virus, and COVID-19 is caused by the SARS-CoV-2 virus. These viruses infect the lungs and breathing passages and are easily spread from person to person.

mRNA-1083 is a messenger RNA (mRNA)-based vaccine. mRNA vaccines aim to teach the body how to make a specific protein that may potentially help your immune system prevent or treat certain diseases. The hope is that the vaccine trains your immune system cells to “remember” these proteins and help your body quickly protect against the strain of infection if exposed in the future.

A Clinical Trial of a Combination Seasonal Flu and COVID-19 Vaccine for Adults

Have tested positive for COVID-19 or been in contact with anyone diagnosed with COVID-19 within 2 weeks prior to study vaccine administration

Have participated in another trial in the past month

Have participated in another study in the past month

Have received routine immunizations appropriate for their age

Be between the ages of 12 and 59 months (1 – less than 5 years old)

This study is evaluating an investigational combination vaccine, called mRNA-1653, to protect against hMPV and PIV3. Both hMPV and PIV3 are known to cause respiratory disease in people of all ages, often in children.

This study will evaluate the safety and immune responses of the mRNA-1653 vaccine when administered to children ages 1 year and less than 5 years of age who have previously had an infection with both hMPV and PIV3 (this could have been just what seemed like a mild common cold).

There are no approved vaccines to prevent hMPV or PIV3 infections. A safe and effective vaccine against hMPV and PIV3 has the potential to substantially improve the health of young children.

A Clinical Trial of a Human Metapneumonovirus (hMPV) and Parainfluenza Virus Type 3 (PIV3) Vaccine in Healthy Adults and Children

A Clinical Study of a Human Metapneumonovirus (hMPV) and Parainfluenza Virus Type 3 (PIV3) Vaccine in Healthy Adults and Children

A Clinical Trial of a Seasonal Flu Vaccine in Healthy Adults

A Clinical Study of a Seasonal Flu Vaccine in Healthy Adults

A Clinical Trial of a Zika Vaccine in Healthy Adults

A Clinical Study of a Zika Vaccine in Healthy Adults

A Clinical Trial of a Personalized Cancer Vaccine for Adults with Solid Tumors

A Clinical Trial of mRNA Vaccines in Adults

A Clinical Study of mRNA Vaccines in Adults

A Clinical Trial of a Seasonal Influenza Vaccine in Adults

A Clinical Study of a Seasonal Influenza Vaccine in Adults

A Clinical Trial of a Seasonal Influenza (Flu) Vaccine for Adults

A Clinical Study of a Seasonal Influenza (Flu) Vaccine for Adults

Have tested positive for COVID-19 or been in contact with anyone diagnosed with COVID-19 within 30 days prior to study vaccine administration

Be receiving treatment with investigational agents for prevention of COVID-19 or treatment of COVID-19 

Have travelled outside of the United States within the last 28 days prior to screening for the study 

Be at least 18 years old and no older than 55 years

Researchers in the mRNA-1283-P101 study are testing if the mRNA-1283 investigational vaccine may be effective in preventing COVID-19.

The study is enrolling individuals who are 18-55 years old and are in good health. Participants in the study will receive either the mRNA-1283 study vaccine or the mRNA-1273 vaccine. mRNA-1283 is not currently authorized for preventing COVID-19.

A Clinical Trial of a COVID-19 Vaccine in Healthy Adults

A Clinical Study of a COVID-19 Vaccine in Healthy Adults

An Observational Study of a COVID-19 Vaccine in Pregnant Women

A Clinical Trial of a Treatment Alone and in Combination with Durvaluman in Patients with Advanced Malignancies

A Clinical Study of a Treatment Alone and in Combination with Durvaluman in Patients with Advanced Malignancies

A Clinical Trial of a Chikungunya Vaccine in Healthy Adults

A Clinical Study of a Chikungunya Vaccine in Healthy Adults

A Clinical Trial of a Cytomegalovirus (CMV) Vaccine in Healthy Adults

A Clinical Study of a Cytomegalovirus (CMV) Vaccine in Healthy Adults

A Clinical Trial of a Human metapneumovirus (hMPV) Vaccine in Healthy Adults

A Clinical Study of a Human metapneumovirus (hMPV) Vaccine in Healthy Adults

A Natural History Study of Patients with Methylmalonic Acidemia (MMA) and Propionic Acidemia (PA)

A Clinical Trial of a Treatment for Patients with Methylmalonic Acidemia (MMA)

A Clinical Study of a Treatment for Patients with Methylmalonic Acidemia (MMA)

Propionic acidemia, or PA, is a rare organic acid disorder causing metabolic crises, seizures, developmental delays, and more. People who are diagnosed with PA are missing the propionyl-CoA carboxylase (PCC) enzyme, which is responsible for the breakdown of certain proteins and fat. When this enzyme is missing, it is difficult for cells in the body to turn food into energy, leading to toxins building up in the bloodstream. Currently, PA is treated by lowering the amount of protein eaten daily, taking dietary supplements or antibiotics, or getting a liver transplant.

Have a confirmed diagnosis of PA based on diagnosis by molecular genetic testing (PCCA and/or PCCB)

Participation in the Paramount Study will last approximately 3 years and includes approximately 54 visits to a clinical trial site.
Participation in the Paramount Study consists of 5 parts:

Insurance is not needed to participate, and qualified participants could receive payment for their trial-related time and travel.

The Paramount Study is evaluating whether an investigational treatment, called mRNA-3927, is safe and effective in reducing the symptoms of PA in individuals 1 year of age and older. mRNA-3927 is an investigational intravenous (IV) infusion treatment that instructs a person’s body to make a properly functioning propionyl-CoA carboxylase (PCC) enzyme.

A Clinical Trial of a Propionic Acidemia (PA) Treatment for Children and Adults

A Clinical Trial of a Combination COVID-19 and Influenza Vaccine for Adults

A Clinical Study of a Combination COVID-19 and Influenza Vaccine for Adults

Often vaccines for viruses are made from a weakened or inactive (not live) virus, but the mRNA-1273 study vaccine is different. It is made from an instructional molecule called mRNA that tells your cells how to make protein. In this case, the protein is a small part of the virus that is thought to help the body’s immune system protect itself if you ever come in contact with the coronavirus.

Be receiving treatment with investigational agents for prevention of COVID-19 or treatment of COVID-19

Have received chronic immunosuppressive therapy for the prevention of organ rejection for a minimum of 3 months

Have received either a kidney transplant or a liver transplant at least six months before screening period

Be unvaccinated OR vaccinated with Moderna’s COVID-19 vaccine under the EUA at least two months prior to consent

Participation in the COVE Transplant Study lasts approximately 13 months and includes approximately seven visits to the study site and nine phone calls.

- Participants will have two injection visits, which will happen on Day 1 and on Day 29.

- Participants will be asked to return to the study site seven days after each injection and then two months, seven months, and 13 months after the first injection. During these study site visits, the study team will monitor for COVID-19 symptoms.

- Participants will be contacted by the study team to monitor for COVID-19 symptoms every four weeks from Day 85 to Day 197, and again from Day 237 to Day 377. During these phone calls, the study team will check how each participant is feeling and ask for updates on their health.

- Participants will also be asked to complete daily eDiary entries for one week after each injection visit. Participants will be asked to complete monthly eDiary entries from Day 71 to Day 183 and from Day 223 to Day 363.

Insurance is not needed to join this trial and compensation for the participant’s time will be available.

Insurance is not needed to join this study and compensation for the participant’s time will be available.

Researchers in the COVE Transplant Study are trying to find solutions to the COVID-19 pandemic that can help everyone – including those who have received a kidney or liver transplant.

The purpose of this study is to evaluate an investigational vaccine that may prevent illness after exposure to SARS-CoV-2, which causes COVID-19. There will be two participant groups in this study – a group of individuals who have had a solid organ transplant and are immunocompromised from the transplant, and a control group of individuals who are in good health. The control group is included as a comparison group to help understand how immune cells act after vaccination. Both groups will receive the COVID-19 vaccine.

Unvaccinated solid organ transplant participants will have the option to receive a third dose of the COVID-19 vaccine. Vaccinated solid organ transplant participants will receive a third dose of the COVID-19 vaccine.

A Clinical Trial of a COVID-19 Vaccine in Kidney or Liver Transplant Recipients

A Clinical Study of a COVID-19 Vaccine in Kidney or Liver Transplant Recipients

Respiratory syncytial virus (RSV) can cause infections of the lungs and respiratory tract. Symptoms can be similar to a cold and may include runny nose, sore throat, cough, and headache. However, RSV can lead to serious conditions like pneumonia, especially in children and older adults. Currently, there is not an approved vaccine for RSV.

Have a history of epilepsy or febrile seizures

For pediatric participants, the total length of participation in this RSV clinical trial lasts approximately 16 months and includes up to 11 clinical trial site visits.

Pediatric participants will be given 3 injections in the upper arm. Each participant has a chance of receiving either the mRNA-1345 investigational vaccine or a placebo. By using a placebo, medical researchers are able to understand if the investigational vaccine is effective in protecting against RSV. Participants will be closely monitored by the clinic team for any side effects.

Pediatric participants will have a mix of in-person and phone visits with the trial doctor to monitor for any symptoms after injections. During these visits and phone calls, the clinical trial doctor and medical staff will check how the participant is feeling and ask for updates on their health.

Parents or caregivers of each pediatric participant will be asked to use an eDiary app on their smartphone or a smartphone will be provided to report any symptoms the participant might experience for 7 days after the injection.

Insurance is not needed to take part in this clinical trial. Compensation for the participant’s trial-related time may be available.

For pediatric participants, the total length of participation in this RSV clinical study lasts approximately 16 months and includes up to 11 clinical study site visits.

Pediatric participants will have a mix of in-person and phone visits with the study doctor to monitor for any symptoms after injections. During these visits and phone calls, the clinical study doctor and medical staff will check how the participant is feeling and ask for updates on their health.

Insurance is not needed to take part in this clinical study. Compensation for the participant’s study-related time may be available.

The mRNA-1345-P101 clinical trial is evaluating the safety and immune response of an investigational vaccine, called mRNA-1345, to protect against Respiratory Syncytial Virus (RSV).

RSV can cause infections of the lungs and respiratory tract. Symptoms can be similar to a cold, and may include runny nose, sore throat, cough, and headache. However, RSV can lead to serious conditions like pneumonia especially in children and older adults. Currently there is not an approved vaccine for RSV.

The mRNA-1345-P101 clinical study is evaluating the safety and immune response of an investigational vaccine, called mRNA-1345, to protect against Respiratory Syncytial Virus (RSV).

A Clinical Trial of a Respiratory Syncytial Virus (RSV) Vaccine for Adults and Children

A Clinical Study of a Respiratory Syncytial Virus (RSV) Vaccine for Adults and Children

A Clinical Trial of an Autoimmune Therapeutic in Healthy Adults

A Clinical Study of an Autoimmune Therapeutic in Healthy Adults

A Clinical Trial of a Zika Vaccine in Adults

A Clinical Study of a Zika Vaccine in Adults

A Clinical Trial of a COVID-19 Booster Vaccine in Adults

A Clinical Study of a COVID-19 Booster Vaccine in Adults

An Extension Study for Participants in mRNA-1647-P202

A Clinical Trial of a Cytomegalovirus (CMV) Vaccine in Healthy Adults of Japanese Descent

A Clinical Study of a Cytomegalovirus (CMV) Vaccine in Healthy Adults of Japanese Descent

A Study to Compare COVID-19 Vaccines in Immunocompromised Adults

A Clinical Trial of a COVID-19 Booster Vaccine for Adults

A Clinical Study of a COVID-19 Booster Vaccine for Adults

A Clinical Trial of an Respiratory Syncytial Virus (RSV) Vaccine for Adults Over 50

A Clinical Study of an Respiratory Syncytial Virus (RSV) Vaccine for Adults Over 50

An Extension Study for Participants Previously Enrolled in the mRNA-3705 MMA Phase 1 Landmark Study

An Extension Study for Participants Previously Enrolled in the mRNA-3927 Propionic Acidemia Phase 1 Paramount Study

A Post-Marketing Safety Study of an Approved COVID-19 Vaccine

Be currently taking any investigational or approved treatments for COVID-19 

Have tested positive for COVID-19 or been in contact with anyone diagnosed with COVID-19 within 2 weeks prior to vaccine administration 

Have received an investigational or approved vaccine for COVID-19  

Have participated in another COVID-19 trial in the past month 

Have participated in another COVID-19 study in the past month 

Participation in the KidCOVE Study lasts up to 17 months and includes phone calls, telemedicine visits, and up to eight visits to the study site.

- In Part 1 and 2 of the study, participants will be given two injections in the upper arm or thigh—about 28 days apart. Participants in these groups have a chance of receiving either the mRNA-1273 study vaccine or the placebo. By using a placebo, medical researchers are able to understand if the study vaccine is effective in preventing COVID-19.

- In Part 3 of the study, participants ages 6 years to < 12 years will be given three injections in the upper arm — the first two doses will be about 28 days apart, and the third dose will be given approximately 4 months after the second dose. All participants in this group will receive the mRNA-1273 investigational vaccine.

- Each part of the study may run in parallel or may close at different times, meaning eligibility may vary based on age and location.

- Participants and their caregivers will be asked to return to the study site up to seven times depending on their enrollment assignment.

- Participants and their caregivers will have two telemedicine visits with the study doctor after each injection, and then monthly after that to monitor for COVID-19 symptoms. During these phone calls, the study doctor and medical staff will check how the participant is feeling and ask for updates on their health.

- Caregivers of participants will be asked to use an eDiary app on your smartphone or a provided smartphone to report any COVID-19 symptoms the participants experience.

- Participants will be closely monitored by the study team if any symptoms of COVID-19 are reported at any time throughout their participation.

The study doctor and medical staff will talk to participants and their caregivers about additional medical support that they will receive if they experience COVID-19 symptoms at any time while in this clinical trial. Insurance is not needed to join this clinical trial, and compensation for your time will be available.

The study doctor and medical staff will talk to participants and their caregivers about additional medical support that they will receive if they experience COVID-19 symptoms at any time while in this clinical study. Insurance is not needed to join this clinical study, and compensation for your time will be available.

The primary purpose of the KidCOVE Study is to test the safety and effectiveness of the study vaccine, called mRNA-1273, that may protect children between the ages of 6 months to < 12 years from getting sick if they come into contact with SARS-CoV-2, which causes COVID-19. Moderna will be recruiting multiple age groups from 6 months to < 12 years and staggering the recruitment of each group. The goal of this study is to evaluate the safety and effectiveness of different dose amounts and regimens, including a three-dose regimen in children 6 to < 12 years. Please be aware that there may be a delay in hearing from a study site, or the site near you may no longer be recruiting in a specific age group.

A Clinical Trial of a COVID-19 Vaccine for Children

A Clinical Study of a COVID-19 Vaccine for Children

Seasonal influenza, also known as the seasonal flu, is a respiratory illness caused by the influenza virus. This virus infects the lungs and breathing passages and is easily spread from person to person. Every year, seasonal influenza causes 3 to 5 million cases of severe illness and up to 650,000 deaths worldwide. Seasonal influenza more severely affects people 65 years of age and older.

COVID-19 is a respiratory illness caused by the SARS-CoV-2 virus. Common symptoms are similar to the flu and include fever, cough, and tiredness. More serious symptoms include difficulty breathing and, in rare cases, death. The World Health Organization declared COVID-19 a pandemic in March 2020. Since that time, there have been more than 500 million cases and 6.2 million deaths worldwide.

Have received a seasonal flu vaccine within the past 5 months

Have received a COVID-19 vaccine (primary series or booster) within the past 4 months

Have completed the 2-dose COVID-19 vaccine primary series

Participation in the Duo P101 Trial will last approximately 7 months and includes up to 5 visits to a trial site and up to 4 safety phone calls.

Participants will be given 1 injection in the upper arm.

Participants will be randomly assigned to receive the investigational combination vaccine or 1 of the active controls. In this clinical trial, the active controls are COVID-19 and seasonal flu vaccines that are either approved for use, previously tested, or currently under investigation. There are no placebos in this trial.

All trial participants will receive the same level of quality care regardless of which vaccine they receive.

Participants will be asked to use an eDiary app on their smartphone (or a provided device) to report any side effects they might experience every day for 7 days after receiving the injection.

The Duo P101 Trial will assess the safety of an investigational combination vaccine, called mRNA-1083, aimed at preventing seasonal flu and COVID-19 infections in adults ages 18 to 79.

Seasonal flu and COVID-19 are respiratory illnesses; seasonal flu is caused by the influenza virus, and COVID-19 is caused by the SARS-CoV-2 virus. These viruses infect the lungs and breathing passages and are easily spread from person to person. Both illnesses more severely affect those over 65.

mRNA-1083 is a messenger RNA (mRNA) vaccine. mRNA vaccines aim to teach the body how to make a specific protein that may potentially help your immune system prevent or treat certain diseases. The hope is that the vaccine trains your immune system cells to "remember" these proteins and help your body quickly protect against the strain of infection if exposed in the future.

RSV is a virus that can cause infections of the lungs and respiratory tract. Symptoms can be like a cold, and may include a runny nose, sore throat, cough, and headache. RSV can lead to serious conditions like pneumonia, which is more common in younger children and older adults.

Once participants join the observational ROSE study, no additional action is needed from them.

Participants will give permission for the study team to collect personal health-related data like past and present health conditions, medical treatment information, hospital stay data, and costs of healthcare. This data will be gathered from medical providers including doctors’ offices, hospitals, pharmacies, and lab companies.

Participants’ health-related data will be kept private using a process called tokenization. This replaces your personal information with a unique string of letters, numbers, or symbols called a token.

Insurance is not needed to participate, and qualified participants will receive payment for their trial-related time.

Insurance is not needed to participate, and qualified participants will receive payment for their study-related time.

Participants enrolled in the mRNA-1345-P301 [ConquerRSV Trial](https://conquerrsv.com/) have the option to participate in the mRNA-1345-P901 ROSE observational study to allow collection of their health-related data for future research.

Participants’ collected health-related data will help researchers better understand respiratory syncytial virus (RSV) and how well investigational RSV vaccines work. The study will also help gather research on other lung diseases, such as COVID-19 and influenza (flu).

Participants enrolled in the mRNA-1345-P301 [ConquerRSV Study](https://conquerrsv.com/) have the option to participate in the mRNA-1345-P901 ROSE observational study to allow collection of their health-related data for future research.

An Observational Study for Participants Previously Enrolled in the ConquerRSV Trial

An Observational Study for Participants Previously Enrolled in the ConquerRSV Study

90% of people in the US are infected with Epstein-Barr virus (EBV) by age 35, but there are currently no approved vaccines to protect against EBV. EBV is the most common cause of Infectious Mononucleosis, or 'mono', which can cause fever, tiredness (fatigue), sore throat, and swollen lymph nodes. It can also cause long-term fatigue and sometimes an enlarged spleen, which can limit activity and, rarely, may require hospitalization. Infection with the Epstein-Barr virus results in lifelong infection and the possibility of developing other diseases, as well. Currently, there is no approved vaccine for EBV or mono

90% of people in the US are infected with Epstein-Barr virus (EBV) by age 35, but there are currently no approved vaccines to protect against EBV. EBV is the most common cause of Infectious Mononucleosis, or 'mono', which can cause fever, tiredness (fatigue), sore throat, and swollen lymph nodes. It can also cause long-term fatigue and sometimes an enlarged spleen, which can limit activity and, rarely, may require hospitalization. Infection with the Epstein-Barr virus results in lifelong infection and the possibility of developing other diseases, as well. Currently, there is no approved vaccine for EBV or mono.

Have participated in another trial within a month of the Screening Visit 


Have participated in another study within a month of the Screening Visit 

Be pregnant or breastfeeding at the time of Screening Visit or be planning to become pregnant or breastfeed at any time while enrolled in the trial 

Be pregnant or breastfeeding at the time of Screening Visit or be planning to become pregnant or breastfeed at any time while enrolled in the study

Be in generally good health, with any chronic conditions well-controlled

The total length of participation in the Eclipse Trial is 18 months and includes up to 15 clinical trial site visits, as well as 10 safety telephone calls.

During the trial visits, participants will answer questions about health, diet, and

quality of life. The trial team will also perform physical exams and blood sample collection. Throughout the trial, participants will use an electronic diary (eDiary) to record any symptoms they might experience after their injection.  During the phone call appointments, the trial team will check how the participant is feeling and ask for updates on their health.

Participants will be given three injections in the upper arm. Participants have a chance of receiving either the mRNA-1189 investigational vaccine or a placebo. By using a placebo, medical researchers are able to understand if the investigational vaccine is effective in protecting against mono. Participants will be closely monitored by the clinic team for any side effects.

Insurance is not needed to take part in the Eclipse Trial. Compensation for the participant’s trial-related time may be available.

The total length of participation in the Eclipse Study is 18 months and includes up to 15 clinical study site visits, as well as 10 safety telephone calls.

During the study visits, participants will answer questions about health, diet, and

quality of life. The study team will also perform physical exams and blood sample collection. Throughout the study, participants will use an electronic diary (eDiary) to record any symptoms they might experience after their injection.  During the phone call appointments, the study team will check how the participant is feeling and ask for updates on their health.

Insurance is not needed to take part in the Eclipse Study. Compensation for the participant’s study-related time may be available.

The Eclipse Trial is evaluating the safety and immune response of an investigational vaccine, called mRNA-1189, that may protect against infectious mononucleosis (also known as mono). Participation in the Eclipse Trial lasts approximately 18 months, including a 28-day screening period, a six-month dosing period, and up to 11 months of follow-up observation.

The Eclipse Study is evaluating the safety and immune response of an investigational vaccine, called mRNA-1189, that may protect against infectious mononucleosis (also known as mono). Participation in the Eclipse Study lasts approximately 18 months, including a 28-day screening period, a six-month dosing period, and up to 11 months of follow-up observation.

A Clinical Trial of an Epstein-Barr Virus (EBV) Vaccine in Young Adults

A Clinical Study of an Epstein-Barr Virus (EBV) Vaccine in Young Adults

RSV is a virus that can cause infections of the lungs and respiratory tract. Symptoms can be like a cold, and may include a runny nose, sore throat, cough, and headache. RSV can lead to serious conditions like pneumonia, especially for younger children, older adults, and those with chronic health conditions.

Have received any mRNA vaccine or COVID-19 vaccine within the past 28 days

Have received an investigational medicine in another clinical trial within the past 180 days

Be 28 to 36 weeks pregnant at the time of vaccine visit (interested individuals can begin the prescreening process if they are earlier than 28 weeks pregnant)


Participation in the RSVoyage Trial will last approximately 15 months, which includes up to 3 months before birth and 12 months after birth. Participation includes at least 8 in-person visits to a clinical trial site and 4 phone calls with the clinical trial team. Once the baby is born, these visits will also include the baby.

Participants will be randomly assigned to receive mRNA-1345 or a placebo. A placebo is a solution that contains no active ingredients and is used as a comparison to understand whether the investigational vaccine works and is safe. All clinical trial participants will get the same level of trial-related care regardless of which injection they receive.

Participants will be asked to use an eDiary app on their smartphone (or a provided device) to report any side effects they might experience every day for 7 days after receiving the injection. Once the baby is born, participants will complete eDiary entries regularly.

Insurance is not needed to participate, and all trial-related procedures and exams will be covered at no cost. Qualified participants will receive payment for their trial-related time and travel.

The RSVoyage Trial will evaluate the safety and immune response of a messenger RNA (mRNA)-based investigational vaccine, called mRNA-1345, aimed at preventing RSV in newborn babies by vaccinating their mothers during pregnancy.

In this clinical trial, the investigational vaccine will be given to a pregnant woman to determine whether it can help protect the baby during the vulnerable first few months by passing on immunity through the placenta.

Young children are at greater risk for severe RSV infection, especially those under 6 months of age, because their respiratory and immune systems are not fully developed.

mRNA-1345 is an investigational mRNA vaccine. mRNA vaccines aim to teach the body how to make a specific protein that may potentially help the immune system prevent or treat certain diseases. The hope is that the investigational vaccine will train immune system cells to "remember" these proteins and help the body quickly protect against RSV if exposed in the future.

A Clinical Trial of an RSV Vaccine for Pregnant Women

A Clinical Study of an RSV Vaccine for Pregnant Women

Respiratory syncytial virus (RSV) is a virus that can cause infections of the lungs and respiratory tract. Symptoms can be like a cold, and may include a runny nose, sore throat, cough, and headache. RSV can lead to serious conditions like pneumonia, especially for younger children, older adults, and those with chronic health conditions.

Have received a vaccine within the past 2 weeks

Have had a confirmed RSV infection within the past 3 months

Have received RSV monoclonal antibodies within the past 6 months

Be 2 to 17 years of age and have a condition that increases the risk of RSV, including asthma, congenital heart disease, cystic fibrosis, Down syndrome, lung disease (and malformations of the lung), neuromuscular disease (such as cerebral palsy), and sickle cell disease

Be 2 to 4 years of age and in good health

Participation in the Imagine Trial will last approximately 7 months and includes at least 2 scheduled in-person clinic visits and 2 scheduled phone calls with the trial team. Those 2 to 4 years of age will have an additional visit, and those 5 years of age or older will have an additional phone call.

All participants will receive 1 injection in the arm.

If your child is 2 to 4 years of age, they will be randomly assigned to receive mRNA-1345 or the placebo. A placebo is a saltwater solution that looks like the investigational vaccine but contains no active ingredients, and is used to compare against mRNA-1345 to determine whether mRNA-1345 is safe and effective.

If your child is 5 years of age or older, they will receive mRNA-1345.

Participants or caregivers will be asked to use an eDiary app on their smartphone (or a provided device) for 7 days after the injection to report any side effects they might experience.

The goal of the Imagine Trial is to evaluate the safety and immune response of an investigational vaccine aimed at preventing RSV in children and teens 2 to 17 years of age, including those with chronic conditions.