The main objective of the study is to evaluate the persistence of the immunoglobulin G (IgG) antibody responses, specific to Alpha-like protein CN (AlpCN), Ribosomal Protein N (RibN), Alpha-like protein 1N (Alp1N), and Alpha-like protein 2 and 3 (Alp2-3N), after a primary vaccination with GBS-NN/NN2 in all participants.

Inclusion Criteria:

• Participant living in Denmark or South Africa who has participated either in Trial MVX0004 (NCT05154578) or MVX0005 (NCT04596878) and has received at least 1 dose of the GBS-NN/NN2 vaccine.
• Participant who is able to read and understand and capable of giving personal signed informed consent.
• Participant who is willing and able to comply with scheduled visits, the investigational plan, and other trial procedures.
• Participant who is granting access to their trial-related medical records and to their trial materials from Trials MVX0004 or MVX0005, whatever is applicable.
• Participant who are expected to be available for the duration of the trial and who can be contacted by telephone during trial participation.

Exclusion Criteria:

• Any personnel involved in the conduct of the trial (and their family members), including, but not limited to, site staff members, MinervaX employees, and any vendor or contract research organisation (CRO) employees.
• Participant with confirmed Group B Streptococcus (GBS) infection since participation in Trial MVX0004 or MVX0005.
• Participant with any psychiatric condition, including recent (within the past year) active suicidal ideation/behaviour that may increase the risk of trial participation or, in the investigator's judgement, make the participant unsuitable for participation in the trial.
• Participant who participated in other trials involving investigational drug(s) or devices within 28 days prior to trial entry, and/or are participating in other trials involving investigational drug(s) or devices at trial entry, or plan to (continue to) participate in other trials involving investigational drug(s) or devices during this trial.
• Participant with known or suspected immunodeficiency or cancer or a family history of congenital or hereditary immunodeficiency.
• Participant receiving chronic administration (defined as more than 14 continuous days) of immunosuppressants or other immune-modifying drugs within 6 months prior to trial entry. An immunosuppressive dose of glucocorticoid will be defined as a systemic dose ≥10 mg of prednisone per day or equivalent. The use of topical, inhaled, and nasal glucocorticoids will be permitted.
• Participant who received blood, blood products, plasma derivatives, or any immunoglobulin preparations in the 12 weeks prior to trial entry or is planning to receive such products during this trial.
• Participant with current or history of drug or alcohol abuse, as judged by the investigator.
• Participant who received any marketed or investigational (other than GBS-NN/NN2 in the MVX0004 or MVX0005 Trial) GBS vaccines or who is planning to receive any marketed or investigational (other than GBS NN/NN2) GBS vaccines during this trial.