One-dose cholera vaccine gives 90 per cent protection

[CAPE TOWN] A dose of oral vaccine provides effective short-term protection against the cholera during an outbreak, a study in Zambia shows.
 
According to researchers, because of a shortage of global stockpile of cholera vaccines, an outbreak in Lusaka, Zambia, in February 2016 necessitated a need for single-dose vaccination.
 
An emergency single-dose oral vaccination campaign was implemented in April 2016, around Lusaka, targeting more than 500,000 people in the city’s overcrowded township areas.
 
Francisco Luquero, a co-author of the study and an expert in preventable diseases at the France-based Epicentre, the research arm of the Médecins Sans Frontières (MSF) or Doctors without Borders, says that studies have already proved that one oral cholera vaccine dose works, but they were conducted in countries that had recently experienced cholera.
 
The 2016 outbreak happened when Zambia had not reported a case of cholera in four years.

“Our results show that people vaccinated can be protected against cholera a few days after receiving one dose.”

Francisco Luquero, Médecins Sans Frontières (MSF)

Between 25 April 2016 and 15 June 2016, researchers enrolled 66 patients with confirmed cholera and 330 people without the disease but who were neighbours of the patients, and determined the effectiveness of the single-dose cholera vaccine.
 
According to the study published last month (8 February) in the New England Journal of Medicine, the effectiveness of the single dose vaccination was about 90 per cent.
 
“Our results show that people vaccinated can be protected against cholera a few days after receiving one dose, which is important in outbreaks because we need to protect people quickly, Luquero says.
 
Oral cholera vaccines are emerging as a new tool for cholera control and have been used in past years to successfully prevent outbreaks in complex emergencies, to curb cholera epidemics or to reduce burden in countries which are endemic but there is a current global shortage, MSF says.
 
The Lusaka outbreak ended quickly after the implementation of the vaccination campaign, thus limiting the number of cases recruited, Luquero explains.
 
The Ministry of Health offered a second vaccine eight months later in December 2016.
 
The WHO estimates that globally cholera infects one to four million people a year, resulting in 21 000 to 143 000 deaths, with countries in Sub-Saharan Africa at increased risk.

“This is an important study because it suggests that the world could face the challenges of cholera outbreak with a single dose,” says Roma Chilengi, chief scientific officer, Centre for Infectious Disease Research in Zambia, adding a single-dose vaccine is cheaper and could help countries with limited financial ability to control the disease.
 
But Chilengi tells SciDev.Net, “It would be helpful to be clear about the potential duration of the protection the single dose offers.”
  
This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.