Immune response to a delayed second dose of oral cholera vaccine

Friday 25 August 2023 - Updated on Monday 11 September 2023

Manufacturers of oral cholera vaccine (OCV) recommend a 7- or 14-days interval between two doses. To carry out two rounds of mass vaccination within this delay is not always feasible and many campaigns implemented to date have used a longer interval. Recent evidence indicates that an extended interval between OCV doses might result in equivalent seroconversion rates and in an improved boosting of mucosal immune responses following the second dose.

Objective

We aim to demonstrate the non-inferiority of the humoral immune response between individuals receiving a second Euvichol-Plus® pre-qualified OCV dose either 6 or 12 months after the initial dose and individuals receiving a second pre-qualified OCV dose 14 days after the initial dose. The humoral immune response will be assessed as the post-vaccination titer of serum vibriocidal antibodies at 14 days post-2nd dose vaccination. Secondary outcomes include the comparison of the overall rate of vibriocidal seroconversion 14 days after either the first or the second vaccine dose. A subsample of individuals ≥ 18 years will have additional serological evaluation to characterize the kinetics of their antibody responses up to 6 months after the second OCV vaccine dose. Although the vaccine is safe, occurrence of adverse events and serious adverse events following vaccination will be assessed (safety evaluation).

Methods

The study is an open-label, randomized, controlled, non-inferiority immunogenicity trial comparing the humoral immune responses to OCV in two interventions arms (6 and 12 months interval between OCV doses) compared with a control arm (standard 14-day interval). In each arm, we aim to recruit 152 individuals aged 1 to 39 year-old eligible for OCV vaccination from the general population (ie. 456 individuals in total).

Country

Republic of Guinea

Status

Recruitment completed. Following ongoing

Our role

Study Coordination

Partners

MSF OCB, Ministry of Health Republic of Guinea, Massachusetts General Hospital, Grieg Foundation

For more information, contact

Fabienne Nackers

Medical Epidemiologist

Contact by mail

[Immersion] in the clinical trial on the administration of a delayed second dose of cholera vaccine in Guinea

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