World Malaria Day 2023
Source: By Dr Paushali Mukherjee: The Indian Express
Malaria has been one of humanity’s greatest scourges for millennia, primarily killing babies and infants. Amongst the human-infecting species of Plasmodium, P. vivax is geographically the most widespread in tropical and subtropical regions, while 95 per cent of all cases of P. falciparum occur in the African region and are associated with severe disease and disease-associated mortality.
Many focussed initiatives, like ‘Roll Back Malaria’ launched in 1998 to reduce deaths from malaria by half by 2010, and a major eradication program launched in 2015, have resulted in a significant reduction in cases and deaths.
Despite these efforts, however, the disease still kills over 400,000 people each year. As feared, Covid-19 pandemic has caused disruption in malaria control, diagnosis and treatment measures. The exact impact of the pandemic is yet to be mapped and understood. It is feared that it may have negatively impacted malaria control measures in a very significant manner.
As we mark World Malaria Day on 25th April – the WHO’s guiding theme this year is “Time to deliver zero malaria: invest, innovate, implement” – there are reasons to be hopeful in our quest to control and finally eradicate malaria, in the form of two first generation vaccines that have recently been developed and may soon be rolled out.
Breakthrough Malaria vaccines
The malaria parasite is extremely complex and elusive, its life cycle involving multiple stages. Scientists across the world have generally found it very difficult to develop efficacious vaccines against malaria. Of more than 100 malaria candidate vaccines to have entered clinical trials in the last three decades, none of them have yet shown the benchmark efficacy of 75 percent set by WHO.
Given the urgency of malaria control and prevention, last year, the WHO gave a historic go-ahead for the first malaria vaccine called RTS,S to be rolled out in high transmission African countries.
This vaccine, a result of collaborative efforts of several organisations across the world, including GlaxoSmithKline (GSK), the Walter Reed Army Institute of Research, the PATH Malaria Vaccine Initiative, the Bill and Melinda Gates Foundation, and the Wellcome Trust, has taken more than 30 years and several hundred million dollars for its development.
Although the RTS,S vaccine has relatively low efficacy, in the range of 30 to 40 per cent, it was granted approval in view of the enormity of the task of malaria control. The vaccine has already been administered to over one million children in pilot trials since 2019, and it has resulted in a significant reduction in severe malaria and hospitalisation in malaria-endemic countries like Ghana, Kenya and Malawi.
Incidentally, an Indian company, Bharat Biotech, based in Hyderabad, has been granted a licence to manufacture this vaccine. Under the agreement, GSK will provide the adjuvant of the vaccine, a key ingredient of any vaccine, and Bharat Biotech is expected to be the only global manufacturer of the vaccine by 2029.
Another malaria vaccine called the R21, which like RTS,S works against the liver stage of the parasite, has recently created much excitement in malaria vaccine research circles. The R21 has been developed by scientists at Oxford University and formulated with proprietary adjuvant from Novavax called Matrix M. This adjuvant has also been used in protein-based COVID-19 vaccine, manufactured and marketed in India by the Serum Institute of India (SII) under the brand name COVOVAX.
Following highly promising results from phase 2 clinical studies, crucial large phase 3 trials of this vaccine have been conducted in several malaria endemic countries in Africa. The results of these trials have also been submitted to WHO for its consideration for prequalification for approval. However, regulatory authorities in Ghana and Nigeria have already given their approval for the vaccine in their respective countries.
Interestingly, R21 vaccine is manufactured by another India company, the SII, which happens to be the world’s largest vaccine manufacturer. Not only is SII the sole manufacturer of the vaccine, it also has sponsored the large Phase 3 licensure clinical trials in Africa. SII has already established capacity to produce 200 million doses annually, underling its commitment to fight against malaria and its eradication.
Malaria vaccine research in India
Understanding the dynamics of vaccine-induced immunity and pre-existing immunity during disease is absolutely essential. Controlled Human Malaria Infection (CHMI) studies have the potential to fast-track initial assessments of vaccine efficacy, and also facilitate the first clinical evaluation of vaccines involving fewer adult subjects. It is not surprising that across the world many countries have developed the capacity to conduct highly safe CHMI studies.
Although basic malaria research is being carried out in many aademic institutions in India, it is not possible to set up human challenge model anywhere in the country.
Scientists at the International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, have successfully developed and produced two experimental recombinant blood stage malaria vaccines against P. falciparum and P. vivax and carried out Phase I first-in-man clinical trials in India. Based on the encouraging results of the Phase I(a) trial with P. vivax vaccine, Phase 2(a) involving efficacy assessment by controlled human malaria infection has been completed in collaboration with scientists at Oxford University.
Needless to say, if the CHMI model was available in India, these completely indigenous efforts would have greatly facilitated the progress of these, and other malaria vaccines, developed in India.
Long Road Ahead
The vaccines against infectious diseases, particularly that target young children, is a long drawn and complex endeavour, as exemplified by development of RTS,S and R21 malaria vaccines.
Development of such vaccines will essentially require collaboration of multiple stakeholders, stable high quality infrastructure and long-term financial support from government and other agencies. It seems quite clear that the current and future vaccines that need to be rolled out in lower and middle-income countries will mostly be manufactured by pharma industries in India. The time is right for India to invest, integrate, and be the leader in finding solutions in combating deadly infectious diseases in the world.
