The safety and efficacy of oral cholera vaccine Shanchol manufactured by the Hyderabad-based Shantha Biotechnics Private Limited, a Sanofi company, have been proved in a large-scale field trial involving 94,675 people in Dhaka, Bangladesh.
The efficacy of the vaccine delivered through routine government services to poor urban populations living in a cholera endemic region was tested.
At the end of two years of follow-up, people in the vaccine group who got one dose of the vaccine showed 37 per cent overall protection against severely dehydrating cholera. The level of protection increased to 53 per cent in those who got the full regimen of two vaccine doses given at an interval of at least 14 days.
Though the protection conferred is not very high, the 53 per cent protection can help save many lives in Bangladesh. There are nearly 300,000 cases and 4,500 cholera deaths every year in Bangladesh.
Surprisingly, the level of protection did increase greatly when vaccination was combined with hand washing. Only a modest 45 per cent protection was seen when one dose was administered to a group (over 92,500 people) that got the vaccine and behavioural change (hand washing). The level of protection shot up to 58 per cent when volunteers in this group received two vaccine doses.
The Dhaka trial reflects real-life conditions, while the efficacy trial [carried out in Kolkata] was carried out in research conditions. The efficacy also varies from country to country depending on the population immunity,” said Dr. Dipika Sur, Consultant Translational Health Science and Technology Institute (THSTI), Department of Biotechnology. She was a part of the team from the National Institute of Cholera and Enteric Diseases, Kolkata, which carried out the trial in Kolkata.
Referring to the level of protection against cholera Dr. Harish Iyer, CEO of Shantha Biotechnics, in an email to this Correspondent, said: “Oral cholera vaccine was given as part of routine healthcare during the trial to reflect real-life situations. The trial confirms that routine vaccination programme with Shanchol in cholera endemic areas could significantly reduce the burden of disease and greatly contribute to cholera control.”
Of particular significance is that the vaccine was found to confer protection even in a highly mobile, high-risk urban population. No significant difference in protection by age was seen, although the level of protection conferred by the vaccine was lower in children younger than five years. The vaccine can be given to children aged one year and above.
Much like Bangladesh, India has very high cholera incidence. According to a June 2015 study published in the journal PLOS Neglected Tropical Diseases, the Indian population at risk of cholera is as high as 411,700,175. The estimated annual number of cases is 675,188 and the estimated annual number of deaths is 20,256. India is one of the eight countries with over 100,000 cases annually.
