A Crimean-Congo haemorrhagic fever vaccine: tolerable and immunogenic in its first human trial

Design

Phase 1, open-label, non-randomised, first-in-human (CCHF01)

Population

46 healthy UK adults aged 18–55

Primary outcome

Safety and tolerability

Effect

No serious adverse events; GP38 IgG median 92.7 AU after dose 1, 1,064 AU after dose 2

CCHF01 was an open-label, non-randomised phase 1 trial at Oxford. 46 healthy adults aged 18–55 received two doses of ChAdOx2 CCHF, a non-replicating adenoviral-vector vaccine, twelve weeks apart.

Reactogenicity was mostly mild: local reactions in 65–68% and systemic reactions in 64–85%, chiefly injection-site pain and fatigue. There were no serious adverse events; one participant stopped for persistent neutropenia and one after a mild allergic reaction. Antibody to the viral glycoproteins rose substantially after the second dose.

There is no approved vaccine for CCHF, a WHO priority pathogen. India has reported human cases, mainly in Gujarat and Rajasthan, among livestock handlers and in hospital outbreaks. This trial shows only safety and antibody response in healthy UK adults; protection has not been tested.

• No CCHF vaccine is approved; this is the first human trial of this candidate.
• Reactions were mostly mild injection-site pain and fatigue, with no serious adverse events.
• Antibody levels rose after the second dose, but protection has not been measured.
• Keep CCHF in the differential for fever with bleeding in livestock handlers and their contacts.

Why it matters

CCHF causes hospital outbreaks in India, and staff currently have no vaccine.

Don't overread it

Antibody responses in 46 healthy volunteers do not show that the vaccine prevents infection.

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