BHUBANESWAR: The cholera vaccination project undertaken at Puri’s Satyabadi has proved to be successful with the latest effectiveness study putting the individual level protection at over 66 per cent.
The ICMR-arm Regional Medical Research Centre (RMRC), which conducted the study, has termed the protection rate to be highly satisfactory, for such a level of individual protective effectiveness will not only help arrest casualties but also curb any severity of transmission.
“Immunising a segment of the community reduces the risk of man-to-man transmission of cholera for the unvaccinated members. Since the Satyabadi study reveals that individual protection is over 66 pc, the herd immunity may be significantly higher,” Director of RMRC Dr SK Kar told this paper on Monday.
A similar study on vaccine effectiveness in Bangladesh in 2005 had shown that 50 pc vaccine coverage gives at least 93 pc population-level effectiveness. Given the 66.1 pc protection rate achieved in Satyabadi, the community-level immunity may be equal or even higher, Kar informed.
In 2011, the RMRC along with Odisha Government launched the pilot vaccination project in Satyabadi block where a population of 33,000 out of 50,000 were vaccinated in two different rounds. The vaccine, Shanchol, provides protection for three years. While the pilot project was well received by the local population, the effectiveness study has proved that a full-fledged vaccination programme through the existing public health system is feasible in the State, the RMRC said.
The study may well have come at the right time for Odisha which has witnessed recurrence of cholera outbreak in Kalahandi, Koraput, Rayagada and Puri districts during the monsoon, sometimes with a severity which has turned into a public health problem.
During 1993 and 2011, severe diarrhoea outbreaks caused by Vibrio cholerae occurred both in the coastal and tribal districts. While two pathogens - Vibrio cholerae O1 and O139 - were initially identified as the carriers, the latest to be spotted was a hybrid which causes severe diarrhoea.
“A major issue with the outbreak is cholera no longer remains water-borne during the initial phases when the severity becomes so strong that man-to-man transmission affects the community. However, the vaccine not only reduces the virulence but also gives increased protection to the unvaccinated population which has been proved by the study,” Kar pointed out.
During the effectiveness study which started in February 2013 and continued till May last, villagers were sampled and rectal swabs were collected at the local health centres and a meticulous analysis was carried out by RMRC.