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Reuters/Joseph Okanga
A malaria vaccine trial in Kenya back in 2010

The new malaria vaccine program for African children is promising but still quite limited  

Paul Adepoju
By Paul Adepoju

Over the coming weeks and months hundreds of thousands of infants under two years old in Ghana, Kenya and Malawi will receive the first vaccine that has demonstrated it can significantly reduce malaria in children through their countries’ national immunization programs.

The vaccine has already been dispatched and the nurses and community workers who will administer it have been trained. The exercise in the three countries will establish the feasibility, impact and safety of the RTS,S malaria vaccine.

But even with the optimism and fanfare in the health development community it is still of limited use.

The RTS,S vaccine does not provide lifelong protection against malaria, only four in 10 children within a specific age group will benefit.

The RTS,S vaccine does not provide lifelong protection against malaria, only four in 10  children within a specific age group will benefit from it and it is less cost-effective than mosquito nets—except if implemented after achieving high mosquito net usage and high coverage of seasonal malaria chemo-prevention which on their own had been largely responsible for year-on-year reduction in deaths due to malaria.

World Malaria Report 2018 says sub-Saharan Africa remains the worst hit region in the world with malaria. In 2017, there were 435,000 estimated malaria deaths globally and six African countries were responsible for nearly half of the deaths — Nigeria (19%), Democratic Republic of the Congo (11%), Burkina Faso (6%), United Republic of Tanzania (5%), Sierra Leone (4%) and Niger (4%).

But none of the countries with the highest malaria burdens would be part of the implementation of RTS,S vaccine that was developed over some 30 years by pharmaceutical giant GSK.

While the individual countries’ health ministries attributed their selection to their country’s impressive immunization programs, WHO revealed their choices stemmed from the requirement of the roll-out which was distinct epidemiological settings in sub-Saharan Africa covering moderate-to-high transmission settings.

Furthermore, the three African countries have had fairly stable incidence of malaria in the most recent three years of available data, making it possible to detect the impact of the vaccine which has been predicted to “lead to an age shift in malaria incidence with children of older ages becoming more affected by disease where enhanced prevention measures are implemented, although the overall benefit is predicted to be positive”.

With vaccine hesitancy emerging as one of the top 10 threats to global health for 2019 according to the WHO, there have been increasing concerns about the fine details of current and future vaccines including side effects and efficacies to justify their usage and to address concerns of parents and local communities that may be reluctant to allow their children to be immunized.

The RTS,S vaccine has quite a number of issues that anti-vaxxers can latch on to and propagate. First of all, it does not provide a lifelong protection against malaria and only children aged 5–17 months will benefit from it.  

The WHO concluded that among younger infants, the vaccine did not work sufficiently well to justify its further use in this age group.

“Lower immune responses are induced by the RTS,S vaccine in infants aged 6–12 weeks compared to children,” WHO stated.

It attributed the observation to possible interference with other vaccines, the mother’s immune system components that are still in the child’s blood and “immaturity of the immune system in the 6–12 week olds compared to the 5–17 month age group”.

To receive maximum benefits, the children will be required to take four doses of the vaccine—the first three doses will be administered at one-month intervals, followed by a fourth dose 18 months later.

“This is going to be an issue,” said Nigerian public health expert Seyi Akinbiyi. According to him, as the number of doses for a vaccine increases, the number of children that will receive the complete dose will drop because of many issues such as logistics and migration. Even if the vaccines are taken from one house to the next, parents cannot be forced to stay at home while waiting for the immunization officials, he said.

Even the WHO and its partners are not entirely sure if it will be feasible to deliver the required four doses of the vaccine in routine settings. They are hoping to know how this can be achieved in the three African countries.

Widespread support

The US government is one of the strongest advocates for the malaria vaccine. The US Center for Disease Control (CDC) believes the vaccine “could prove to be a powerful tool in building upon the gains made over the past decade”. It added vaccine has the potential to: reduce the healthcare associated costs of managing malaria patients.

“It could also end the emerging problem of drug resistance and the need for insecticides used to kill mosquitos,” the CDC said in a statement.

But the WHO was careful in raising high hopes. “The RTS,S vaccine is proposed as a tool to complement the existing package of WHO-recommended malaria preventive, diagnostic and treatment measures and will be used in combination with the current interventions,” the global health agency said.

From the perspective of the WHO, the vaccine will complement other tools including long-lasting insecticidal bed-nets, spraying inside walls of dwellings with insecticides, preventive treatment for infants and during pregnancy, prompt diagnostic testing, and treatment of confirmed cases with effective anti-malarial medicines. “Deployment of these tools has already dramatically lowered malaria disease burden in many African settings.”

The agency was right. Between 2000 and 2015, the rate of new malaria cases in sub-Saharan Africa fell by 42% and malaria mortality rates fell by 66% even though the region continues to account for approximately 90% of global malaria cases and deaths.

While the three chosen African countries have high hopes for the vaccine as evident in their willingness to include it in their individual country’s national immunization program, the WHO is being transparent and public  about its partial effectiveness.

“As RTS,S is only partially effective, it will be essential that any vaccinated patients with a fever be tested for malaria, and that all those with a confirmed malaria diagnosis are treated with high quality, effective anti-malarial medicines,” WHO advised.

Read next: How to avoid infection if you’re visiting a malaria region

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