RTSS Vaccine and PBO Net Impact on Malaria Infection and Transmission in Malawi

Introduction: The decline in malaria incidence has stalled globally and incidence is increasing in some high transmission settings of sub-Saharan Africa, including Malawi. The situation is worsening despite the scale-up of previously effective interventions, raising concerns that the impact of current malaria control and prevention strategies maybe compromised.

Problem: There is an urgent need for innovative approaches to malaria control and Malawi is currently positioned to assess two of the most promising new interventions. The Malawi Ministry of Health (MOH) is launching large scale projects to evaluate a new formulation of insecticide-treated bed nets with a chemical synergist, piperonyl butoxide (PBO), designed to enhance the insecticidal effect of pyrethroids and the new malaria vaccine RTS,S (RTS,S). In an effort to gain the most information from these, interventions Malawi's National Malaria Control Programme (NMCP) have invited the Malawi International Center for Excellence in Malaria Research (ICEMR) to evaluate the effectiveness of the two interventions (alone and in combination) on malaria prevalence and transmission.

Objective: In this proposed implementation study, we propose to assess the impact of PBO nets and RTS,S vaccine on Plasmodium infection prevalence and transmission.

Study type and methodology: We will enroll children in a prospective cohort study in which the follow-up will be at the 2nd, 4th, and 6th month. We are selecting two health center catchment areas: one in which both RTS,S and PBO nets are available through the government health system and one in which there is no RTS,S vaccine available and standard long-lasting insecticide-treated nets (LLINS) have been distributed through the public section. At each visit, we will collect specimens to identify malaria infection and detect gametocyte infections. We will also collect and analyze mosquitoes from 100 households in both catchment areas to provide an entomological evidence of the force of infection. Children in households that are scheduled to receive both PBO nets and RTS,S vaccine will be compared to children in households that are not scheduled to receive either of these interventions.

Inclusion criteria

• Children aged 7 to 18 months of age (age-eligible for at least 3 doses of RTS,S doses) OR being one of not more than two children living in the household of an enrolled age-eligible child and being >18 mos and < 10 years of age.
• Not on cotrimoxazole prophylaxis for HIV infection
• Weight >5 kg
• Permanent residence of Health Centre (HC) catchment area
• Residence within 10 km from the HC
• Written informed consent from parent/guardian for the child to participate in the study

Exclusion criteria

Non-residents of the catchment area and visitors to the study area will be excluded because the study requires follow-up for at least 6 months and access to interventions such as conventional, PBO nets and malaria vaccination.