Expert calls for cholera vaccine roll-out in Haiti

A leading cholera expert has called on the WHO to mobilise a new vaccine so it can be used in Haiti’s cholera epidemic.

Stephen Calderwood, chief of the infectious diseases division at the Massachusetts General Hospital, United States, said the vaccine — Shanchol — is cheap and effective and should be rolled out with minimum delay.

Shancol is already on sale in India and Vietnam but is awaiting ‘prequalification’ by the WHO’s Prequalification of Medicines Programme, which ensures the quality, safety and efficacy of medicines — essential before they can be distributed internationally by the UN and US agencies.

The vaccine was first developed in 1997 and has been used in Vietnam since 1998, where it is licensed as ORCVAX. It was then adapted in 2004 by scientists at the International Vaccine Institute, South Korea, to meet WHO production guidelines. More recently, Shanchol passed phase III clinical trials in India, where it reduced cholera incidence by two thirds among 70,000 people, in 2009.

"I think there is already adequate data for the use of the vaccine in the epidemic — [the WHO] should be buying vaccine right now and getting it to Haiti," said Calderwood.

"For some reason Shanchol has not yet been prequalified. I communicated with the WHO recently and I think they are going to move ahead and prequalify it," he said.

A spokesperson for the WHO’s Department of Immunization, Vaccines and Biologicals said that the organisation does not comment on applications for prequalification. But on the WHO website, Shanchol remains on the lowest priority setting of the list of vaccines for which pre-qualification applications have been made.

Another problem for a possible deployment is the low quantities of vaccine available.

In Haiti, more than a million people have been displaced since January’s earthquake and could potentially be at risk from the cholera outbreak which began in mid-October and has killed more than 1,000 people and hospitalised around 16,000.

But according to preliminary data from the US Centers for Disease Control (CDC), only around 150,000 doses of Shanchol are available. A vaccination regime requires two doses.

Kashmira Date, a medical doctor at the CDC’s Global Immunization Division, disputed Calderwood’s contention that there is enough efficacy data to use the vaccine.

She also highlighted practical obstacles. The vaccine requires two doses administered two weeks apart. This may be difficult to achieve in a population hit by natural disasters.

The WHO recommends that local authorities consider pre-emptive (before an outbreak starts) or reactive (after the outbreak begins) vaccination during outbreaks, but says there is a lack of experience with using cholera vaccines to halt ongoing outbreaks, such as the one in Haiti.