Typhoid vaccine found to be 84% effective in preventing the disease in children

Reviewed by Emily Henderson, B.Sc.Oct 12 2021

A vaccine has proved safe and effective in protecting children against typhoid, raising hopes of fighting the disease in Sub-Saharan Africa, a study says.

More than 1.2 million cases of typhoid and 18,703 deaths from typhoid occur every year in the region, according to the researchers. The World Health Organization (WHO) recommended the typhoid conjugate vaccine in 2018 for use in countries where the disease is endemic.

A clinical trial conducted in Malawi shows that a single dose of typhoid conjugate vaccine -the only typhoid vaccine licensed for children as young as six months old - prevented typhoid in a about 84 per cent of 14,069 children aged nine months to 12 years.

"It is a great result for Malawi and for Africa," says Melita Gordon, a co-author of the study and a professor of clinical infection, microbiology and immunology at the University of Liverpool and the Malawi-Liverpool-Wellcome Trust Clinical Research Programme.

"We were the only site chosen for the trial on the continent. The other sites were in Nepal and Bangladesh and the results were completely consistent across the three sites."

Malawi is a typhoid-endemic country, recording between 400 and 500 cases per 100,000 every year, according to Queen Dube, chief of health services at Malawi's Ministry of Health.

While typhoid is treatable, its effects can go beyond illness and death, researchers say. It can impair physical and cognitive development in children, affect school attendance and performance, limit productivity and reduce earning potential.

Gordon tells SciDev.Net that the findings published in the New England Journal of Medicine last month are a big boost for Malawi and Sub-Saharan Africa's campaign against typhoid.

The existing vaccine could not be used in very young children. In addition, the first line antibiotics have been found to be ineffective against multi-drug resistant strains. With this vaccine, we can now expect a reduced typhoid burden."

Melita Gordon, co-author of the study

The three-year study that started in 2017 included 28,000 children, aged between nine months and 12 years, and recruited from primary schools and communities in two locations in Blantyre, Malawi's commercial city.

"We were able to complete our study on budget and ahead of schedule because of the great enthusiasm from communities. We planned to be seeing 200 children in a day but as much as 600 could turn up on some days," Gordon explains.

After 18 to 24 months of surveillance, the vaccine was found to be safe, with no serious adverse effects on children. It also worked equally well on pre-school aged children.

Gordon explains that the study encountered challenges such as a few children moving out of the research sites within the study period, and COVID-19 forced them to suspend the study for two months.

"However, we eventually managed a good retention rate due to regular text messaging to parents and the hard work of health surveillance assistants in mobilisation activities," she adds.

The efficacy data of the typhoid conjugate vaccine is the first in Africa, according to Gordon, who hopes that other African countries will follow Malawi's example in planning to roll out the vaccine.

Dube says that Malawi's Ministry of Health is setting up systems within its extended programme of immunisation to guide health workers ahead of the roll out in September 2022. "Vaccines are the best tool in as far as prevention is concerned, so we are getting set," Dube tells SciDev.Net.

Maziko Matemba, a Blantyre-based community health expert and director of Health and Rights Education Programme Malawi, describes the result as "a big breakthrough", adding that what remains now is dissemination of information to promote acceptance of the vaccine.

"Typhoid is a big problem in Africa. Vaccination is a cost-effective way of fighting disease, and this is a great opportunity for us," Matemba says.