First the children are measured, then weighed. And then they get a lollipop. Later, once everything is finished, they get another one - a small reward for their role in helping change the world.

"Thank you for participating in the study," Dr. Ally Olotu, a man in a striped shirt, says to the mothers of six children sitting on wooden benches in front of him at a modest health center in Kiwangwa, Tanzania. It's the final test date for a vaccine that could save hundreds of thousands of lives a year.

Olotu, 47, a doctor and researcher from the capital city of Dar es Salaam, isn't the only one who sees this as a breakthrough. A short time ago, the NGO Malaria No More said recent progress could mean the end of children dying from malaria "in our lifetime."

The R21 vaccine, developed at the Jenner Institute at Oxford, will be only the second to be launched against malaria. It is designed to protect young children from the often fatal disease. On this day, the last 20 or so of 600 children in Tanzania will be administered their fourth vaccine in the testing process. The third test phase has already been completed in Mali, Burkina Faso and Kenya. A total of 4,800 children have received the vaccine.

Olotu is a renowned expert in his field in Tanzania. He was involved in the evaluation of the first vaccine approved in 2021, Mosquirix, developed by the British pharmaceutical company GlaxoSmithKline. The World Health Organization recommends the use of Mosquirix, even though it hasn't proven to be the miracle cure many had been hoping for. It offers a level of protection of only 30 to 40 percent.

Olotu has high hopes for R21. "The malaria pathogen is a very tricky parasite that keeps morphing," he says. "It's a much more complex organism than, say, a virus. That makes it difficult to develop an effective vaccine."

And yet it appears that scientists have succeeded. R21 could become the first vaccine to achieve the World Health Organization target of at least 75 percent efficacy. That, at least, is what a series of tests conducted by Olotu and his colleagues suggests. Of the more than 100 vaccines that have been developed and tested over the past few decades, none has come close to providing this level of protection.

Malaria Is Present in Around 100 Countries

Indeed, creating that level of protection would be an epochal achievement. Malaria today remains one of the world's deadliest diseases. A child dies of the illness an average of almost every minute. In its most recent World Malaria Report, the World Health Organization estimates that 247 million people were infected in 2021. An estimated 619,000 died.

The disease is present in around 100 countries. In addition to sub-Saharan Africa, the disease is most prevalent in Southeast Asia, India and in Central America and parts of South America. There are five species of the Plasmodium parasite that cause malaria in humans. Of those, the pathogen Plasmodium falciparum is particularly dangerous: It causes malaria tropica, the most severe of all forms of malaria.

Sub-Saharan Africa is more affected than any other region of the world. In 2021, the WHO Africa region accounted for around 95 percent of all malaria cases and 96 percent of all deaths. It is home to a species of mosquito that is particularly efficient at transmission and also the most deadly of all forms of malaria. Around 80 percent of the malaria deaths in the region are children under the age of five. That's around 475,000 deaths. And scientists like Olotu believe the actual death toll is far higher.

Back at the Tanzanian health center, small freezers are now being carried into an adjoining room, where the vaccine is stored at below 8 degrees Celsius (46 degrees Fahrenheit). Daria Rukesa is sitting on a blue plastic chair, her son Bosco on her lap, talking about the kind of suffering the disease can cause.

The 28-year-old is wearing a nice dress and has tied her hair back tightly. She's proud that Bosco is able to participate in the series of experiments. "I'm not just helping him, I'm helping all the children here," she says. Her son has had three vaccinations, one a month. Now, a year later, he's here for a booster shot.

Before he was even six months old, Bosco had already had malaria twice. "He almost died once," his mother says. She embraces the boy in the white and blue patterned T-shirt as if still worried about losing him. "I was really scared," she says. For a month, the infant wrestled with death, lying apathetic in his bed with a high fever and then on a drip in a small hospital. Rukesa says she prayed for her son. It took him another month to recover.

Bosco is now almost two years old. Perhaps the vaccination has already saved his life.

"I know a lot of people in our community who have died from malaria," the mother says. Until recently, she says she heard about deaths every time she visited the hospital. The disease also killed her nephew. Overall, though, the situation has improved in recent years. People are using mosquito nets more frequently as well as sprays and creams to deter the insects.

Access to the Healthcare System

Malaria is transmitted by female Anopheles mosquitoes. When a mosquito bites someone, the parasitic protozoa enters their blood. If a mosquito bites an infected person and then bites another person, it continues to transmit the disease. The parasites enter through the liver into the bloodstream, where they multiply en mass, causing the liver cells to burst and releasing them back into the bloodstream. There, they penetrate the red blood cells and continue to multiply.

The attack on the blood cells triggers the symptoms. The rhythmically recurring fever attacks typical of malaria occur, as well as headaches, fatigue, vomiting and pain in the limbs. In the worst case, it can cause seizures, kidney failure and death.

But it is possible to prevent death. Malaria, Olotu says, is a disease of poverty. In the vast majority of cases, he says, it is only people who aren't treated quickly who die, which is a real problem in Africa, where the nearest clinic can be a long journey, often on foot. So, it's not just a vaccine that's needed – better access to healthcare systems is also necessary.

And progress. "The more developed a society is, the better the homes people live in, and the less malaria there is." If the roofs of homes are airtight, nets are installed on the windows and the doors are closed, then fewer mosquitoes are likely to be present during the time when the anopheles mosquito is most likely to hunt for blood: between sunset and sunrise.

Little Vaccination Skepticism

"On the other hand, if people live in simple huts and there are enough others carrying the parasite, the transmission rate gets out of control," Olotu says. He's now standing under a tree in front of the health center, where he's about to hold a team meeting. Looking out at the clinic, Olotu says we probably would have had vaccines earlier if the world's rich suffered from malaria.

Olotu has been working in the field of malaria since 2005, first as a pediatrician and later as a researcher in Tanzania, Kenya and Equatorial Guinea. Through a window, he can now see vaccines being taken out of the freezers in small bottles inside the building. The control group is to be given both R21 and a vaccine against rabies. To assess the effectiveness of R21, 200 of the 600 children participating in the trials will be administered a different vaccine.

He says the vaccination skepticism that still persists today with the coronavirus barely exists in this realm. "Everyone here knows about the danger of malaria," he says.

In fact, the scientists at Oxford who developed R21 were also involved in the Astra-Zeneca vaccine against the coronavirus. At Oxford, where around 50 researchers have spent 10 years working on R21, they say many things were easier than they have been with corona.

Whereas the coronavirus has fewer than 20 genes, Plasmodium, which causes malaria, has more than 5,000. The R21 vaccine targets a specific surface protein early in the pathogen's development and attempts to prevent the parasite from reaching the liver and reproducing there.

No Long Approval Process

"In that regard, the already approved and the new R21 vaccine are very similar," Olotu explains. Both contain a surface protein of the parasite that is carried into the body on part of a hepatitis virus. But in R21, the amount of hepatitis virus was reduced and the amount of malaria protein increased. The aim is to enable the immune system to concentrate more on the formation of antibodies against malaria. Researchers also used a more potent effect enhancer.

Olotu is confident that more children will soon be able to get vaccinated. "Given the similarity to the previously approved substance, we can avoid a long approvals process," he says. Olotu is hopeful that R21 could be on the market as early as the end of this year.

In Oxford, officials are already expecting the first routine vaccinations to happen in the coming months. On April 13, the Jenner Institute announced the approval of R21 in Ghana, followed last week by Nigeria, the country with the world's most malaria deaths.

The vaccine has already been licensed to the Serum Institute of India, the world's largest manufacturer of vaccines, where 100 to 200 million doses per year can be produced. And it does so for a retail price of just a few dollars per dose. "We are looking toward the end of child deaths from malaria," says Olotu. "That's fantastic."