In malaria vaccine research, bright hopes and formidable challenges

In malaria vaccine research, bright hopes and formidable challenges

Subject: Science and technology

Section:

Malaria Facts and Features

• Life-threatening disease spread to humans by some types of mosquitoes
• Mostly found in tropical countries
• Higher risk of severe infection – Infants, children under 5 years, pregnant women, travellers and people with HIV or AIDS
• Preventable by avoiding mosquito bites  and curable with medicines
• Malaria infection during pregnancy can also cause premature delivery or delivery of a baby with low birth weight.
• Kills over 4,00,000 people each year

Vector and Causes

• Spreads through the bites of some infected female Anopheles mosquitoes
• Blood transfusion and contaminated needles transmit malaria

Disease causing Microbes

• 5 Plasmodium parasite species cause malaria in humans.
• falciparum and P.vivaxpose the greatest threat.
• falciparum – deadliest malarial parasite and the most prevalent on the African continent. 95% of all cases of P.falciparum occur in the African region and are associated with severe disease and disease-associated mortality.
• vivax – geographically most widespread in tropical and sub-tropical regions. Dominant in most countries outside of sub-Saharan Africa
• Other 3 Plasmodium species infecting humans – malariae, P. ovale and P. knowlesi

Symptoms

• Most common early symptoms – fever, headache and chills
• Symptoms usually start within 10–15 days of getting bitten by an infected mosquito
• Symptoms may be mild to severe
• Severe symptoms include – Abnormal bleeding, difficulty in breathing, jaundice, impaired consciousness, multiple convulsions
• Early treatment for mild malaria stops infection from becoming severe
• The vaccine has been shown to significantly reduce malaria, and deadly severe malaria, among young children.

Two New Breakthrough in Vaccination

1. Since October 2021, WHO recommends broad use of the RTS, S /AS01 malaria vaccine among children living in regions with moderate to high  falciparummalaria transmission – high transmission African countries
2. R21, which like RTS, S works against the liver stage of the parasite

About RTS, S Vaccine

1. A result of collaborative efforts of several organisations around the world including GlaxoSmithKline (GSK), Walter Reed Army Institute of Research, PATH Malaria Vaccine Initiative, Bill and Melinda Gates Foundation, and Wellcome Trust.
2. Taken more than 30 years and several hundred million dollars to develop
3. Relatively low efficacy of 30-40%
4. Already been administered to over a million children in pilot trials since 2019
5. Resulted in a significant reduction in severe malaria and hospitalization in malaria-endemic countries like Ghana, Kenya, and Malawi.
6. Hyderabad-based Bharat Biotech – granted a licence to manufacture this vaccine. Expected to be the only global manufacturer of the vaccine by 2029. GlaxoSmithKline (GSK) will provide the vaccine’s key ingredient adjuvant.

About R21 Vaccine

1. Developed by scientists at Oxford University.
2. Formulated with proprietary adjuvant from Novavax called Matrix M
3. This adjuvant has also been used in the protein based Covid-19 vaccine manufactured and marketed in India by SII under the brand name
4. Crucial large scale phase 3 trials of this vaccine have been conducted in several malaria endemic countries in Africa after successful phase 2 clinical studies.
5. Regulatory authorities in Ghana and Nigeria have already approved the vaccine in their countries. Submitted for WHO consideration.

What is an Adjuvant

An adjuvant is an ingredient used in some vaccines that helps create a stronger immune response in people receiving the vaccine. In other words, adjuvants help vaccines work better.

Initiatives to reduce malarial causes and deaths

1. Roll Back Malaria launched by WHO in 1998 – to reduce deaths from malaria by half by 2010
2. A major malaria eradication programme launched in 2015

These have resulted in significant reduction in malaria causes and deaths.

Challenges Associated

1. Malaria parasite is extremely complex and elusive, with a life cycle involving multiple stages – very difficult to develop efficacious vaccines against malaria.
2. Of the more than 100 candidates that have entered clinical trials in the last three decades, none shown the benchmark efficacy of 75% set by the WHO.
3. Covid-19 pandemic has disrupted malaria control, diagnosis, and treatment measures.

Other Facts

1. WHO’s guiding theme 2023 – “Time to deliver zero malaria: invest, innovate, implement”
2. World Malaria Day— observed every year on April 25

Serum Institute of India

Serum Institute of India (SII) is a Pune based world’s largest vaccine manufacturer by number of doses produced and sold globally. SII has already established the capacity to produce 200 million doses annually, underlining its commitment to the fight against malaria and its eradication.

Research in India

1. 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.
2. Basic malaria research is being carried out in many academic institutions in India. But human challenge model or CHMI is not set up.
3. 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 falciparum and P.vivax and carried out phase1 first-in-man clinical trials in India.
4. CHMI studies with P.vivax vaccine for efficacy assessment has been completed in collaboration with scientists at Oxford University.

Current and future vaccines for lower-and middle-income countries will mostly be manufactured in India. So India has to invest, integrate, and be the leader in finding solutions to combat deadly infectious diseases in the world.

About International Centre for Genetic Engineering and Biotechnology (ICGEB)

• The ICGEB is a unique intergovernmental organisation initially established as a special project of UNIDO.
• Autonomous since 1994, it runs over 45 state-of-the-art laboratories, in Trieste, Italy, New Delhi, Indiaand Cape Town, South Africa.
• Forms an interactive network with almost 70 Member States, with operations aligned to those of the United Nations System.
• It plays a key role in Biotechnology, promoting Research excellence, Training, and Technology Transfer to industry, to contribute in concrete terms to sustainable global development.
• The ICGEB currently has 66 full Member States, a further 19 countries are still pending ratification of, or accession to, the Statutes of ICGEB.