For a foot soldier on the cutting-edge of a global public health experiment, Michael Kenyali was looking a little wobbly.
The bright-eyed two-year-old, stumbling towards his mother and wailing to be fed, is part of an army of babies enlisted to test a new vaccine researchers hope will help drive back malaria, one of Africa's biggest killers.
"My firstborn used to have problems with malaria. He would go into seizures," said Michael's mother Mariam, sitting outside her small, neat homestead near the Kenyan coastal town of Kilifi as her other children, aged 11, 6, and 4, looked on.
"The baby was the same before he went into the study," she said, smoothing Michael's forehead. "But since he got into the vaccine study, he hasn't had any problems."
Unsure of vaccine's efficacy
It's still too early to tell if Michael's good health has anything to do with the "RTS,S" malaria vaccine, which will be rolled out early next year in the largest clinical trial ever undertaken in Africa.
Michael, who participated in one of the preliminary studies, received either the malaria vaccine or a similar dose of rabies vaccine, a "placebo" designed to benefit participants even if they were not in the malaria group.
Researchers hope results from the coming trial, involving 16 000 children in seven African countries and funded by groups supported by the Gates Foundation among others, will mirror data from a 2004 study in Mozambique.
That study of more than 2 000 children showed the vaccine reduced all cases of clinical malaria by 35% and the worst cases of the disease by almost 50%.
Babies have to be studied
Because babies are the chief victims of malaria, they must also be the among the test subjects for any new vaccine. For RTS,S, this means recruiting thousands of mothers across Africa who are willing to volunteer their children for the next phase of the study.
"The rights and ethics issues are very important," said Dr Omar Juma, field coordinator for RTS,S studies at the Bagamoyo District Hospital north of Tanzania's capital Dar es Salaam.
"There is a tradition of wariness in the community on any foreign issue. They don't want to be guinea pigs. They are very aware of safety issues."
What's in it for them?
Earlier RTS,S trials around Bagamoyo have given recruiters a sense of what works - and what doesn't - in the rural communities where they are seeking volunteers.
"If you want to talk about a vaccine, first you have to talk about the disease," Juma said. "What people want to hear is: are you going to care for the kids?"
Fatima Stilihari, 30, is a mother of five and member of the Community Advisory Board for Ifakara charged with overseeing the links between the medical researchers and the community.
"It's advantageous for the community because the kids get treated quickly when they are sick. They get drugs which are not always available at the government hospitals. You get free transportation when the child needs to go to the hospital."
Stilihari said some mothers were unsettled by the issue of drawing blood, sensitive in a culture where blood is regarded as precious. But most came round when they heard of the improved health care their babies would receive in the study.
Wants to be part of study
"Many women around here are jealous if they are not in the study," she said. "So far, everything is going well. We are getting good services."
Mwaganza Mrisho, 34, decided to volunteer her youngest son Chuma for the vaccine study after an older child got sick with malaria despite the family using insecticide-treated bed nets.
"We were still getting sick," Mrisho said, sitting in a small thatched lean-to that served as a local snack bar offering rice, beans and steamed porridge.
"I hoped that if my child got the vaccine, then he wouldn't fall sick. Sometimes he gets a fever, or a cough, like all kids, and then I call Bagamoyo. A car always comes to pick him up to see the paediatrician."
Chuma so far has not come down with malaria, and Mrisho said it seemed all the local children who were enrolled in the preliminary study were doing well: "I'm definitely encouraging other mothers to take part." – (Andrew Quinn/Reuters Health)
Malaria killed 1 million in 2006