Follow-up of the immune response ten years after intradermal or subcutaneous yellow fever vaccination

In order to protect the large susceptible population in subsaharan Africa
against yellow fever, in the scope of the outbreak in Angola which started in
January 2016, mass vaccination campaigns have been conducted. Nevertheless, the
yellow fever vaccine stockpile had been depleted twice since the start of the
outbreak, which calls for creative solutions to augment this stockpile.

Our research published in 2008 showed a non-inferior immune response (measured
in neutralizing antibodies) to 1/5th dose of yellow fever vaccine injected
intradermally, compared to the standard subcutaneous dose.

Based on these results, the WHO advised to vaccinate with a fractional dose
(1/5the of the standard dose) in the following vaccination campaign in
Kinshasa. As no long term results are available on the immune response after
interdermal yellow fever vaccination, we propose to measure the neutralizing
antibodies response in the participants of the trial 10 years ago.

To investigate the long term (ten years) protective immune response to
fractional yellow fever vaccination (1/5th of the standard dose, injected
intradermally), compared to the standard subcutaneous vaccination

- follow-up of a previously conducted trial (randomized, controlled, single
centre study)
- one blood sampling (8cc) for serology

- no risk (only 1 blood sample)
- benefit: knowledge on the long term protection to intradermal fractioned
yellow fever vaccination, which is directly applicable to the current mass
vaccination campaign in subsaharan Africa in order to protect a large
susceptible population against yellow fever