Phase 2b Study of VXB-221 and VXB-213 Protein Vaccine for Prevention of Respiratory Syncytial Virus and Human Metapneumovirus Infections in Adults ≥60 Years

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What is this study about?

The study focuses on infections caused by Respiratory Syncytial Virus and Human Metapneumovirus, viruses that can lead to serious lung problems in older adults. The vaccine being tested is a bivalent protein vaccine called RSV+HMPV protein vaccine (618), which contains two active components named VXB-221 and VXB-213. It is given as an injection into the muscle.

The purpose is to determine whether the vaccine can prevent the first episode of lower respiratory tract disease (LRTD) caused by these viruses within a year. Participants aged 60 and older will be randomly assigned to receive either the vaccine or a saline solution (placebo), and neither the participants nor the study staff will know which was given. Over approximately 12 months, participants will have regular check‑ups to record any respiratory illnesses, reactions at the injection site, and other health events.

Safety monitoring includes looking for any unwanted effects, especially serious adverse events (SAEs) and adverse events of special interest (AESI). Some participants may provide blood samples so the study can measure how well the immune system responds to the vaccine.

1 initial visit and vaccination

you arrive at the study site after having agreed to take part in the trial. a healthcare professional will confirm that you meet all study requirements.

you will receive a single dose of either the rsv+hmpv protein vaccine (the test product) or a 0.9% nacl diluent (the placebo). the injection is given intramuscularly in the upper arm.

the volume of the injection is the amount specified by the study protocol and is administered once at this visit.

2 post‑injection observation

after the injection you will remain at the clinic for about thirty minutes while staff watch for any immediate reactions such as redness, swelling, fever, or feeling unwell.

if any reaction occurs, staff will provide appropriate care and record the event.

3 symptom diary period

for the next seven days you will keep a written diary to note any symptoms, side effects, or changes in how you feel. this includes local reactions at the injection site (such as pain or swelling) and systemic reactions (such as fever, headache, or fatigue).

the diary helps the study team evaluate the safety of the vaccine or placebo.

4 first follow‑up visit (approximately 1 month)

you will return to the study site about one month after the injection. during this visit staff will ask about any health events that occurred, review your diary, and may collect a small blood sample to measure immune response.

the visit also includes a brief physical check to ensure you are feeling well.

5 subsequent follow‑up visits (3, 6, and 12 months)

additional visits are scheduled at roughly three months, six months, and twelve months after the injection. each visit follows the same pattern: discussion of any new health problems, review of any side effects, and collection of a blood sample to assess long‑term immunity.

these visits continue for a total of twelve months, which is the period used to evaluate whether the vaccine prevents respiratory infections.

6 final assessment and study completion

at the twelve‑month visit the study team will perform a final health assessment, review all collected data, and close your participation in the trial.

no further study‑specific medication or injections are given after this point.

Who Can Join the Study?

You must be at least 60 years old on the day you join the study.
You must be considered eligible by the doctor after a medical evaluation that includes reviewing your medical history (information about past illnesses and health), doing a physical examination (the doctor checks your body), and using the doctor’s clinical judgment (professional decision based on the information).

Who Cannot Join the Study?

Having a weakened immune system (known or suspected), having taken medicines that suppress the immune system in the past 6 months, taking strong steroids like prednisone for more than 2 weeks in the last 3 months, or having a nerve disease caused by the immune system.
Being allergic (having a systemic hypersensitivity) to any ingredient in the vaccine or having had a life‑threatening allergic reaction to similar products before.
Having a long‑term (chronic) illness that the doctor thinks could interfere with taking part in the study or finishing it.
Having previously had Guillain‑Barré Syndrome (GBS), a rare condition where the immune system attacks the nerves and can cause weakness.
Having already received a vaccine or antibody treatment for RSV or HMPV, including any licensed or experimental vaccine (even if it was a single‑component or combination vaccine) or a monoclonal antibody (a lab‑made protein that targets the virus).

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country
Stichting European Clinical Research Alliance on Infectious Diseases	Utrecht	The Netherlands
Innomedica OÜ	Tallin	Estonia
Rokotetutkimuskeskus Finvac Oy	Tampere	Finland
Ecg Medica S.L.	Valencia	Spain
Bellvitge University Hospital	L'hospitalet De Llobregat	Spain
Synexus Polska Sp. z o.o.	Poznan	Poland
Gyncentrum Sp. z o.o.	Katowice	Poland
Futuremeds Sp. z o.o.	Wroclaw	Poland

Other Sites

Site Name	City	Country
Merelahe Haldus ja Eriarstiabi OÜ	Pohja-Tallinna Linnaosa	Estonia
Doktor Brno s.r.o.	Brno	Czechia
Hospital Universitario Hm Puerta Del Sur	Mostoles	Spain
Kkitvqmggst Ueftwsmcq Kshqzh Oj	Tartu	Estonia
Db ohrophyr sssfov	Jindřichův Hradec	Czechia
Uszdtribmsby Mkmidnx Clzysgw Uovkaxd	Utrecht	The Netherlands
Tcxtr Uodhgsowwf Hpndjjov	Tartu	Estonia
Pwsaqpwtkjq swbltq	Olomouc	Czechia
Aukcc sdspse	Ceske Budejovice	Czechia
Hanbofgl Uvnyyycnew Chdxwkn Hlngyreo	Helsinki	Finland
Sccikj Tlxjssxyyju Oj	Turku	Finland
Hnjemhkc Cpolvt Dy Bxnjcrjok	Barcelona	Spain
Untnsasvgioy Du Swivdejx Dl Clrjlprsah	Santiago De Compostela	Spain
Ecg Oilsu Sfm Ady Curagjs Smlcmh	Centelles	Spain
Epcdt Dtlhcrtavwcrqidafqn Pvibtkwk Vdr Smryfj	Vic	Spain
Hpsagfqd Pzjehu Suqo	Vigo	Spain
Hvqfusqs Ufmcokbuyvmje Hd Mlcttknszkwbl	Boadilla Del Monte	Spain
Pfbozv Sfzw	Skorzewo	Poland

Trial status

Country	Status	Recruitment Start
Czechia	Not yet recruiting	13.10.2026
Estonia	Not yet recruiting	13.10.2026
Finland	Not yet recruiting	13.10.2026
Poland	Not yet recruiting	13.10.2026
Spain	Not yet recruiting	13.10.2026
The Netherlands	Not yet recruiting	13.10.2026

Trial locations

RSV+HMPV protein vaccine (618)
This is a bivalent protein vaccine that contains two experimental proteins, known by the code names VXB-221 and VXB-213. It is given as an injection into the muscle. The vaccine is designed to teach the immune system to recognize and fight two common viruses that cause serious lung infections in older adults: respiratory syncytial virus (RSV) and human metapneumovirus (HMPV). By stimulating the body’s defenses, the vaccine aims to reduce the chance of developing lower‑respiratory‑tract disease (such as pneumonia or bronchitis) caused by these viruses over the following year.

Respiratory syncytial virus lower respiratory tract disease – This condition is caused by infection with respiratory syncytial virus, which initially produces cold‑like symptoms and then spreads to the lower airways. The virus inflames the bronchioles and lung tissue, leading to cough, wheezing, and difficulty breathing. Mucus production increases and can partially block the small airways. The illness often starts with a runny nose and fever before the lower respiratory signs appear. It is most common in young children and older adults, but anyone can be affected. The disease progresses as the infection moves deeper into the lungs, increasing respiratory discomfort.
Human metapneumovirus lower respiratory tract disease – This disorder results from infection with human metapneumovirus, which first causes upper‑respiratory symptoms and then spreads to the lower respiratory tract. Inflammation of the bronchioles and alveoli leads to coughing, shortness of breath, and wheezing. Excess mucus may accumulate, narrowing the airways. The condition often follows an initial sore throat or mild fever. It can affect people of all ages, with children and the elderly being more susceptible. The disease advances as the virus replicates in the lower airways, increasing respiratory irritation.

Trial ID:

2026-526177-42-00

Protocol code:

VCA25397

Trial Phase:

Therapeutic exploratory (Phase II)

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Phase 2b Study of VXB-221 and VXB-213 Protein Vaccine for Prevention of Respiratory Syncytial Virus and Human Metapneumovirus Infections in Adults ≥60 Years

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?