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Most children abandoning malaria vaccine's final dose

Without the fourth dose, protection drops quickly to zero. It's a critical dose in boosting antibodies

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by JOHN MUCHANGI

Health09 October 2023 - 19:00
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In Summary


  • The fourth vaccine dose boosts antibodies and maintains protection at about 36 per cent over the next 48 months.
  • “There was an 81 per cent dropout in RTS,S dose four compared to the first dose,” the analysis shows.
A nurse administers a malaria jab during the launch of the expansion of the malaria vaccination programme to 25 additional subcounties in the endemic lake regions on March 7

Health workers are struggling to reach children with the final dose of the malaria vaccine, which is critical in sustaining protection.

The majority of the children who started vaccinations have dropped out without completing the fourth dose, the latest analysis by the Ministry of Health suggests.

The RTSS vaccine is administered as a primary three-dose vaccination, each given a month apart, followed by a critical booster (fourth dose) several months later.  

“There was an 81 per cent dropout in RTS,S dose four compared to the first dose,” the analysis shows.

The fourth dose in Kenya is given 15 months after the third dose.

RTSS’s efficacy is high in the first six months after the three monthly doses but without a booster shot, this efficacy wears out quickly to zero within two years, according to the World Health Organization's Full Evidence Report on the RTS,S/AS01 Malaria Vaccine.

The Kenyan study, published in the Malaria journal two weeks ago, shows service-based coverage was relatively high, with 96 per cent coverage for dose one, 87 per cent for dose two, and 78 per cent for dose three.

“However, coverage dropped significantly for the fourth dose, with only 39 per cent of children receiving it,” shows the report, prepared jointly by the ministry, Kemri-Wellcome Trust Research Programme, and the University of Oxford.

Service-based coverage refers to children taken to health facilities for other vaccines, such as polio, but also qualify for the malaria jab. 

When looking at population coverage, only 78 per cent of eligible children got the malaria vaccine dose one, 68 per cent dose two, 57 per cent dose three, and only 24 per cent dose four.

The fourth vaccine dose boosts antibodies and maintains protection at about 36 per cent over the next 48 months.

Health authorities are now deliberating whether to flex the requirement on when children receive the fourth dose.

One way is to align with other vaccines so that children can receive the fourth malaria dose when they come for, say, the measles-rubella vaccine second dose (MR2).

“However, it should be noted that a review of timing alone may not be adequate to achieve catch-up, as the MR2 vaccine also faces persistently high dropout rates,” says the report, titled ‘Malaria vaccine coverage estimation using age-eligible populations and service user denominators in Kenya.’

“Additional strategies may include instituting follow-up procedures for children who miss doses and providing reminders, such as mobile text messages, to improve routine compliance,” the authors say.

The authors include Dr Rose Jalang’o, the Ministry of Health official spearheading the roll out.

Others from the Kemri Wellcome Trust are Angela Moturi, Anitah Cherono, Samuel Muchiri, Robert Snow, and Emelda Okiro.

The vaccine was created in 1987 and began pilot implementation in Kenya, Malawi and Ghana in 2019. 

The Kenya analysis considers all jabs given for 36 months until August 2022.

The vaccine is administered to children aged six, seven, nine and 24 months.

Experts say although the efficacy of the RTS,S vaccine is modest, it still provides significant public health benefits.

Phase 3 results demonstrated that among children who received four doses of vaccine, 1,744 clinical malaria cases were prevented for every 1,000 children vaccinated.

Modelling studies conducted by four different groups under WHO supervision found that four doses will avert 116,480 cases of clinical malaria and 484 deaths per 100,000 children vaccinated.

The Kenyan report reveals that over the 36-month implementation period, a total of 818,648 doses of RTS,S were administered.

Facilities managed by the Ministry of Health and faith-based organisations were responsible for over 88 per cent of all vaccines delivered, demonstrating the collaborative effort required to distribute the vaccine effectively.

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