It’s not unexpected that a malaria vaccine needed to be developed. The burden of malaria and its sequelae has been far-reaching, especially among infants and under-five children in Nigeria, accounting for numerous deaths among Nigerian children.
As Africa’s most populous country, Nigeria carries the highest burden of malaria globally, accounting for approximately 27% of the global malaria burden and 31% of malaria deaths worldwide. According to the 2023 World Malaria Report, nearly 200,000 deaths occurred from malaria in Nigeria, with under-five children and pregnant women being the most affected. The national malaria prevalence rate of malaria in children aged 6-59 months was 22% as of 2021.[1]Nigeria Receives Malaria Vaccines Ahead of Roll Out
Preventive interventions like insecticide-treated mosquito nets (ITNs), insecticide sprays, and prophylactic drugs in pregnancy have been the mainstay of malaria prevention in Nigeria. Insecticide-treated mosquito nets, which are one of the most effective methods of malaria prevention,[2]Comparative effectiveness of malaria prevention measures: a systematic review and network meta-analysis | Parasites & Vectors reduced malaria deaths by 20% among children under five in 2023[3]Insecticide-Treated Nets | Malaria | CDC but this is still far from ideal.
Factors associated with the poor efficacy of pre-existing malaria prevention include poor coverage and utilization, growing insecticide and drug resistance, as well as limited resources and infrastructure for widespread implementation.
Due to the above, it becomes pertinent to develop and adopt a malaria vaccine that solves the problem of poor compliance, and to a large extent, resistance, distribution, and coverage problems.
Malaria Vaccine Developmental Timeline
The development of a malaria vaccine started over 60 years ago in the early 1960s, a journey that was inspired by the remarkable success of vaccines against polio, measles, diphtheria, tetanus, rabies, and other diseases. The reason for the long delay in the full development of malaria vaccines is due to the clever nature of the parasite, and its complex life cycle and genome, in keeping with the fact that parasites are generally difficult to develop vaccines against.[4]Malaria vaccines: the 60-year journey of hope and final success—lessons learned and future prospects | Tropical Medicine and Health
Continuous research on the malaria vaccine has been ongoing by GSK (GlaxoSmithKline), in collaboration with GAVI (Global Alliance for Vaccination and Immunization), UNICEF, and PATH (Program for Appropriate Technology in Health), for the development of a malaria vaccine that is both effective and safe. This process has been facilitated by funding from donor organizations including the Bill & Melinda Gates Foundation, amongst others.
On October 6, 2021, the World Health Organization approved the RTS,S/AS01 (RTS,S) malaria vaccine against P. falciparum, the most deadly malaria parasite globally and the most prevalent in Africa. Before the official approval, pilot studies were conducted by delivering 18 million vaccine doses through the Malaria Vaccine Implementation Programme (MVIP) to Ghana, Kenya, and Malawi.[5]WHO recommends groundbreaking malaria vaccine for children at risk
These studies showed that the vaccine improved equity and coverage of malaria prevention, is safe and effective with over 75% efficacy, and can be seamlessly used together with other methods of malaria prevention. The initial 18 million malaria vaccine doses allocated also enabled nine more countries to benefit from the malaria vaccination, excluding Nigeria.[6]RTS,S | Malaria Vaccines
Malaria Vaccine Rollout in Nigeria
On October 17, 2024, Nigeria rolled out a new Oxford R21/Matrix-M malaria vaccine. This vaccine is different from the RTS,S/AS01 earlier developed by GSK, it is developed by the University of Oxford, and the Serum Institute of India, in collaboration with several partners and is shown to have a higher efficacy than RTS,S in clinical trials, with results indicating up to 77% effectiveness in preventing malaria.[7]Reuters. Nigeria rolls out new Oxford R21 malaria vaccine. 2024
In line with Nigeria’s National Malaria Elimination Programme, the malaria vaccine introduction envisions a malaria-free Nigeria in collaboration with existing preventive interventions like long-lasting ITNs.
As of October 17th, the Minister of Health, Muhammad Ali Pate, said Nigeria had received 846,200 doses of the malaria vaccine, procured in partnership with GAVI, the Vaccine Alliance, and UNICEF, while anticipating a balance of 153,800 more doses to make 1 million doses on October 26, 2024.[8]Ibid., Reuters, 2024
The first phase of the rollout was scheduled to start with two pilot states, Kebbi and Bayelsa in November 2024, ahead of the national rollout due to the particularly high malaria prevalence in that belt, with over 800,000 doses to be distributed during this phase.[9]Nigeria receives malaria vaccines ahead of roll-out
However, these vaccines were recently rolled out in Nigeria and delivered to the Government of Nigeria in Abuja on October 17, 2024; an event that has been described as a critical milestone in the fight against malaria in Nigeria.[10]JOINT PRESS RELEASE Nigeria Receives Malaria Vaccines Ahead of Roll Out | WHO | Regional Office for Africa
What is the R21 Malaria Vaccine?
Nigeria is the second country to approve the R21/Matrix-M malaria vaccine, only after Ghana. The R21 vaccine is a recombinant protein subunit vaccine. The vaccine is designed to target the circumsporozoite protein (CSP) of the Plasmodium falciparum parasite, which is the most lethal malaria-causing species.[11]GAVI – Five things you need to know about the new R21 malaria vaccine
The CSP is an antigen mimic of a protein on the surface of the sporozoite, the first form of the malaria parasite that enters the body. The sporozoites are introduced into the bloodstream by the mosquito following a blood meal and then migrate to infect the liver and red blood cells where they continue development, causing all the signs and symptoms of malaria.
The introduction of the R21 vaccine thus stimulates the immune system to recognize and attack the malaria sporozoite antigen, resulting in the destruction of the parasite and prevention of further development and infection of other body tissues.
The vaccine also includes the Matrix-M adjuvant which is designed to enhance the body’s immune response to the vaccine to improve its effectiveness and boost antibody production against the sporozoite antigen.
Vaccination Schedule for the Malaria R21 Vaccine in Nigeria
Starting with Kebbi and Bayelsa state, the malaria vaccine has been incorporated into Nigeria’s Routine Immunization schedule
The R21 malaria vaccine involves administering three primary doses at one-month intervals, followed by a booster dose approximately 12 months later. This regimen is designed to protect against malaria, especially for children aged 5 to 35 months. The booster dose administered approximately 12 months after the last primary dose enhances the vaccine’s efficacy.
In comparison with the RTS,S vaccine, both have four total doses but the fourth dose of the RTS,S vaccine is not given as a booster dose, which in addition to the incorporation of the Matrix-M adjuvant makes the R21 vaccine more effective than the RTS,S vaccine. In areas where malaria remains a significant public health problem in children a year after the fourth dose, a fifth dose might be considered, depending on local assessment of feasibility and cost-effectiveness.
Mode of Administration
The malaria vaccines (both RS21 and RTS,S) are administered as a 0.5ml intramuscular injection into the deltoid or anterolateral thigh. This aligns with typical practices for subunit protein vaccines, ensuring an optimal balance between efficacy and safety.
Again, each of the first three doses is given at an interval of one month apart starting from 5 months old. A booster dose is given 12 months after the last dose, while a fifth dose may be given if need be.
Side Effects
The R21 vaccine has undergone clinical trials in the UK, Thailand and several African countries, as well as pilot studies in Ghana and Nigeria. So far, no serious complications have been associated with the vaccine’s administration.[12]FACTSHEET: What you should know about the latest malaria vaccine and what it could mean for Nigeria – Africa Check
However, its side effects are similar to those observed with other vaccines. These include pain and tenderness at the injection site, and occasional fever in children.
Overall, the malaria vaccines, including the R21 vaccine are relatively safe for use in all vulnerable groups, with a high efficacy profile.
Potential Challenges With Malaria Vaccination
Despite the availability of the malaria vaccines, possible challenges could be anticipated with respect to acceptance and vaccine coverage. Challenges related to acceptance are not strange but with the incorporation of malaria vaccination into the routine programme on immunization, acceptance is likely going to be higher than for other classes of vaccines.
More pressing challenges we could anticipate regarding malaria vaccination include financial constraints, fragmented cold distribution chains, and other logistic challenges. The complex interplay of social, cultural, biological, political, and educational factors could affect the utilization and coverage of this vaccine.
Frequently Asked Questions
Who is the vaccine intended for?
The vaccine primarily targets children aged 5 to 36 months, the group most vulnerable to severe malaria and death in malaria-endemic regions like Nigeria.
How effective is the vaccine?
The R21 vaccine has demonstrated an efficacy rate of 75-80% when paired with a booster dose, making it a significant advancement in malaria prevention.
What is the vaccine schedule?
The vaccination schedule includes three initial doses administered one month apart, followed by a booster dose given after 12 months.
What are the side effects of the vaccine?
Reported side effects include mild pain or tenderness at the injection site and occasional fever. No severe side effects have been documented in clinical trials.
Where will the vaccine be administered in Nigeria?
Initial rollouts are likely to focus on regions with the highest malaria prevalence, including Kebbi and Bayelsa. Distribution will expand as infrastructure and logistics improve.
How is the vaccine funded?
The rollout is supported by international organizations like GAVI, WHO, and UNICEF, along with contributions from the Nigerian government and other partners.
Will the vaccine replace other malaria prevention methods?
No, the vaccine is an additional tool. Insecticide-treated bed nets, indoor residual spraying, and antimalarial drugs remain essential components of malaria control strategies.
What are the challenges to the vaccine rollout?
Challenges include maintaining cold chain logistics, addressing vaccine hesitancy, ensuring adequate healthcare personnel, and securing sufficient funding.
How will the effectiveness of the vaccine be monitored?
Monitoring and evaluation frameworks will track vaccine uptake, coverage, and impact on malaria cases and deaths. Data collection will be critical to assess long-term effectiveness.
How does the R21 vaccine compare to the RTS,S vaccine?
The R21 vaccine offers higher efficacy (up to 77%) compared to the RTS,S vaccine and requires fewer doses for sustained protection.
How can I access the vaccine for my child?
Information about vaccine availability and administration sites will be disseminated by Nigeria's Ministry of Health and other partners as the rollout progresses.
