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Study of pneumococcal vaccines in healthy young adults, older adults and people with HIV infection

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial studies the immune system response to pneumococcal vaccines in different groups of people, including young healthy adults, older adults, and people living with HIV. The study will examine how two different types of pneumococcal vaccines - Prevenar 20 and Pneumovax 23 - affect the formation of special structures in lymph nodes called germinal centers, which are important for immune system function.

The study involves taking small samples from lymph nodes and blood to analyze how the immune system responds to vaccination. Participants will receive a single dose of one of the pneumococcal vaccines through an intramuscular injection. The researchers will monitor the immune response for up to 6 months after vaccination by collecting blood samples and small amounts of saliva.

The research aims to understand how factors like age and HIV infection influence the body's response to different types of vaccines. This knowledge could help improve vaccination strategies for different groups of people. The study will also look at how lifestyle factors such as diet, exercise, and smoking might affect the immune response to vaccination.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial vaccination

    You will receive one of two pneumococcal vaccines: either Prevenar 20 or Pneumovax 23.

    The vaccine will be administered as an intramuscular injection.

  2. Step 2

    7-day follow-up

    A blood sample will be collected to analyze serum biomarkers.

    A sample from your lymph node fluid will be collected for analysis.

  3. Step 3

    4-week assessment

    At 28 days after vaccination, your lymph nodes will be examined using ultrasound to measure their size.

    A small sample of lymph node fluid will be collected to study immune cell formation.

    Blood samples will be taken to analyze serum biomarkers.

  4. Step 4

    10-week follow-up

    At day 72 after vaccination, additional blood samples will be collected.

    Your lymph node fluid will be analyzed again.

  5. Step 5

    6-month final assessment

    Blood samples will be collected to analyze your immune response to the vaccine.

    A saliva sample will be collected to check for pneumococcal bacteria.

    This marks the completion of your participation in the study.

Who can join the trial?

7 criteria

  • You must be either between 20-40 years old OR over 60 years old
  • You must be in generally good health
  • Both men and women can participate
  • If you are living with HIV:
    • You must be between 20-40 years old
    • You must have documented HIV infection
    • You must be currently taking anti-retroviral therapy (medications that treat HIV)
    • Your viral load must be less than 200 copies per milliliter (this means the HIV virus is well-controlled in your body)

Who cannot join the trial?

15 criteria

  • Active infections or fever (temperature above 38°C/100.4°F) at the time of vaccination
  • Previous severe allergic reactions to any pneumococcal vaccines or their components
  • Receipt of any vaccine within 30 days before study enrollment
  • Current participation in another clinical trial
  • Pregnancy or breastfeeding
  • History of severe allergic reactions or anaphylaxis to any medications
  • Any condition that, in the opinion of the investigator, would make participation unsafe
  • Use of immunosuppressive medications (drugs that weaken the immune system)
  • Bleeding disorders or use of blood thinners
  • Any serious chronic medical condition that is not well-controlled
  • History of autoimmune disease (conditions where the immune system attacks healthy body tissues)
  • Recent blood transfusion or receipt of blood products within the last 3 months
  • Current substance abuse or alcoholism
  • Mental conditions that would interfere with study compliance
  • Unable to follow study procedures or attend follow-up visits
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Investigated drugs

  • Prevenar 20

    is a vaccine that protects against 20 different types of the bacteria that cause pneumonia. It works by attaching pieces of the bacteria to a harmless protein, which helps the immune system recognize and fight the real germs. In this study, participants receive the vaccine by injection into the muscle, and researchers look at how well it creates a special area in the immune system called the germinal centre, which is important for long‑term protection.

  • PNEUMOVAX 23

    is a vaccine that protects against 23 different types of the bacteria that cause pneumonia. It contains purified pieces of the bacterial surface that trigger the immune system to make antibodies. In the trial, this vaccine is used as the comparison (comparator) to see how the newer 20‑type vaccine performs. It is also given by injection into the muscle, and the study measures the germinal centre response after it is given.

What is already known about the treatment

  • Prevenar 20

    This vaccine is given as a 0.5 ml intramuscular injection using a pre‑filled syringe containing a liquid suspension. It is an approved, widely used vaccine that has been studied in many clinical trials and is listed in official medical references. The vaccine is meant to protect against infections caused by 20 different types of pneumococcus. It works by attaching sugar molecules from each bacterial type to a harmless protein (CRM197) and adding aluminum phosphate, which helps the body’s immune cells recognize the sugars and produce protective antibodies. It belongs to the class of conjugate vaccines (bacterial polysaccharide‑protein conjugate, ATC J07AL02).

  • Pneumovax 23

    This vaccine is administered as a 0.5 ml intramuscular injection of a clear solution. It is an approved, long‑standing vaccine that is well documented in medical literature and guidelines. The vaccine is used to prevent disease from 23 different pneumococcal types, especially in adults and people with higher risk. It contains purified sugar molecules from each bacterial type that directly stimulate the immune system to make antibodies, without needing a protein carrier. It is classified as a polysaccharide vaccine (purified pneumococcal polysaccharide, ATC J07AL01).

Investigated diseases

  • HIV infection

    A viral infection that affects the immune system by targeting CD4+ T cells, which are crucial for fighting off infections. The virus gradually weakens the body's natural defenses by reducing the number of these important immune cells. HIV infection progresses through several stages, during which the virus continues to multiply and affect more immune cells. The condition affects the body's ability to respond effectively to various pathogens and can make people more susceptible to other infections. Over time, without intervention, the virus leads to a progressive decline in immune function. The infection can be transmitted through specific bodily fluids, including blood, breast milk, and during sexual contact.

  • Pneumococcal infection

    A bacterial infection caused by Streptococcus pneumoniae that can affect various parts of the body. The bacteria can colonize the upper respiratory tract and potentially spread to other areas. The infection commonly begins in the sinuses or lungs but can also affect other body parts. The bacteria can be present in the body without causing illness, a state known as colonization. The infection is more common in people with weakened immune systems and can spread between people through respiratory droplets.

Trial detailsLast updated 21 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-510354-16-00Protocol code2023-510354-16-00Estimated enrolment75 patientsSponsorLeiden University Medical Center

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