NEW YORK/GENEVA, OCTOBER 20, 2016—A new cholera control strategy using a single-dose oral vaccine instead of two doses could be sufficient in protecting against the deadly disease during an outbreak, according to a study published by international medical humanitarian organization Doctors Without Borders/Médecins Sans Frontiéres (MSF) in the Lancet Global Health this week.
The study—conducted in Juba, South Sudan by MSF, Epicentre, the South Sudanese Ministry of Health, John Hopkins University, and the World Health Organization—found that the single-dose vaccine strategy was 87.3 percent effective in reducing cholera for up to two months among the nearly 900 people who took part in the study. Additionally, this strategy could help maximize public health benefits by vaccinating and protecting more people when supply is low or when it is impossible to administer a second dose of the traditional two-dose vaccine.
“The results of the study are very promising,” said Dr. Iza Ciglenecki, MSF operational research coordinator. “More research is needed, and we still don’t have full knowledge of the length of the coverage after two months. Nevertheless, this could be a milestone in cholera protection, as it may allow for the prevention of unnecessary illness and death during outbreaks. Given the lack of available vaccines, this is very good news.”
While oral vaccines have proven effective in preventing cholera during outbreaks, current two-dose strategies are logistically challenging to implement during emergencies. In addition, the global shortage of oral cholera vaccine currently makes it impossible to protect the more than two billion people at risk of the disease. Fewer than four million doses of oral cholera vaccine were produced in 2015.
As part of a cholera outbreak response in Juba in July 2015, MSF, in collaboration with local health authorities, vaccinated 160,000 people with a single-dose of oral vaccine. This was the first time a single dose of oral vaccine had been used in a mass vaccination campaign. The decision was made since there were not sufficient doses available to vaccinate all of the at-risk population with two doses, and evidence from previous studies suggested that a single dose might provide sufficient short-term protection.
In April 2016, MSF also vaccinated 423,000 people in Lusaka, Zambia, in the largest ever single-dose oral cholera vaccination campaign to take place during an outbreak.
Cholera causes death and illness of thousands of people globally every year, mainly affecting the most vulnerable and poor. The disease is endemic in many parts of the world and outbreaks often occur during emergencies such as natural disasters and conflicts, where poor or dense living conditions contribute to the spread of the disease.