PHILADELPHIA - Vaccinating populations after an outbreak of cholera has already begun could be a powerful way of controlling the growth of an epidemic according to scientists reporting to the American Society of Tropical Medicine and Hygiene here. London School of Hygiene & Tropical Medicine MSc graduate Rita Reyburn - who’s been researching epidemics in Zimbabwe, Zanzibar and Calcutta with the International Vaccine Institute of Korea and working with Lorenz von Seidlein from the Menzies School of Health Research, Casuarina, Australia - told Peter Goodwin about their calculations which have validated the later use of vaccination to protect those who haven’t already been infected.