Evaluating a Unique Typhoid Vaccine in Zimbabwe
Though the burden has drastically decreased in most industrialized nations, typhoid fever remains a serious health risk in much of the world. Spread through contaminated food and water, an estimated 26 million cases of typhoid fever occur worldwide each year, causing approximately 215,000 deaths. In countries like Zimbabwe, where the disease remains endemic, typhoid poses a recurring threat, particularly in the crowded urban areas around the capital city, Harare.
“Harare has grown exponentially, and new informal settlement areas have been developed. These areas are not covered by the city’s water and sewage systems,” said Nandini Sreenivasan, an epidemiologist at the Centers for Disease Control and Prevention (CDC). “In the last couple of years, the number of typhoid cases in Harare has really increased.”
Access to safe water, adequate sanitation and hygiene, and vaccination are required for typhoid prevention and control. While improvements in water and sanitation infrastructure are occurring in several parts of the world, rapid urbanization and population growth poses enormous challenges for construction of new systems and maintenance and upgrades of existing ones.
Typhoid vaccination is an important complementary tool for preventing typhoid, particularly in light of the rapidly increasing threat of antimicrobial resistance. Burdened by recurring outbreaks of typhoid in the country, Zimbabwe’s Ministry of Health and Child Care reached out to Gavi, a global vaccine alliance dedicated to broadening access to new and underused vaccines, for an emergency supply of typhoid conjugate vaccine. Though other typhoid vaccines exist, the typhoid conjugate vaccine provided distinct advantages, particularly for young children.
“This newer typhoid conjugate vaccine is more effective, and it can be given to children as young as six months, where the other typhoid vaccines can only be used for children aged two and up,” Sreenivasan said. “It is also just a single dose, and it provides a longer duration of protection.”
Completed over one week in February and March of 2019, the vaccination campaign reached 320,000 people in nine suburbs of Harare. In the months that followed, CDC, in partnership with the CDC Foundation, supported Zimbabwe’s Ministry of Health and Child Care in conducting an evaluation of the typhoid surveillance system and the vaccination campaign. In addition, CDC and the CDC Foundation also partnered with the University of Zimbabwe to conduct a community assessment of the water, sanitation and hygiene situation in the suburbs targeted by the vaccination campaign. The information gathered through the evaluations will inform national introduction using the same vaccine planned by the Ministry of Health and Child Care later in 2020.
“We discussed evaluation objectives with the Ministry of Health team, reviewed their data with them, developed protocols in collaboration with them, worked with them to hire data collectors and supervisors and collaborated to implement the evaluations,” Sreenivasan said. “We worked closely together in every step of the process.” And while that collaboration was successful, the rollout of the campaign in Zimbabwe faced many challenges. Scheduled initially to launch in January 2019, the campaign was delayed due to a wave of political unrest that swept the country. Once the vaccination campaign was completed, an ongoing financial crisis in Zimbabwe further complicated the post-campaign evaluations, compounded by critical fuel shortages that forced them to make changes to data collection schedules.
“When we were going out to the field for the coverage survey, the vehicles had to leave in time for them to get back to the gas stations for fuel, because the fuel lines could be six or eight hours long,” Sreenivasan said.
Throughout the evaluation period, the CDC Foundation provided support, implementing agreements with the in-country partners like the World Health Organization, who in turn helped with logistics and hiring. In addition to purchasing supplies for the evaluations, like tablets for data collection, the Foundation also managed the financial agreements with the partners and provided staff to assist with conducting the evaluations.
Overcoming many hurdles, the evaluations of the campaign—the first Gavi-supported TCV campaign in Africa using the vaccine for outbreak response and control—netted valuable information for Zimbabwe’s Ministry of Health and Child Care and for other countries to use in future campaigns. For Sreenivasan, a medical doctor with previous experience participating in outbreak response, the work with the evaluation teams in Zimbabwe was uniquely gratifying.
“I’ve gotten to work with the same people over a long period of time and build up relationships,” Sreenivasan said. “And that’s been really rewarding.”
In partnership with Gavi, the CDC Foundation is assessing a Typhoid Conjugate Vaccine (TCV) delivered as part of a ministry of Health-led campaign in Harare, Zimbabwe. This evaluation will provide lessons learned and recommendations for future use of TCV in outbreak settings, and to inform typhoid control strategies.