A randomized, single-blinded clinical pilot study to assess whether vaccination with live attenuated vaccines can induce trained immunity and cause beneficial changes in patients with COPD.

Single-blinded 1:1:1 block randomized controlled trial (with varying block sizes of 3-6), stratified by sex. A total of 60 participants will be recruited and randomly assigned with 20 in each treatment arm. Separated by three months, the participants will receive two doses of one of the following three treatments:

1. MMR vaccine (M-M-R VaxPro)
2. BCG vaccine (Danish strain 1331)
3. Saline (placebo)

Inclusion Criteria:

• Specialist verified and spirometry-confirmed COPD
• Age > 40 years.
• Negative HIV-test.
• Able to give informed consent.

Exclusion Criteria:

• Acute febrile illness.
• Known allergy to BCG or MMR vaccines or serious adverse effects at previous vaccination.
• Allergy to MMR vaccine components, neomycin, or egg proteins.
• Known prior, active, or latent infection with mycobacterium tuberculosis.
• Pregnancy or breastfeeding.
• Vaccination with a live vaccine within the last 4 weeks.
• Being severely immunocompromised (HIV-1 infection, organ- or bone marrow transplantation, chemotherapy, primary immune defect, anti-cytokine therapy, immunosuppressant treatment).
• Oral or intravenous corticosteroid at dose of ≥10 mg/day with duration over 3 months.
• Active solid or non-solid malignancy or lymphoma, excluding basal cell carcinoma within 2 years.
• Treatment with immunoglobulins within the last 3 months or expected treatment with immunoglobulins for the duration of the trial.