Page 62 - The lraternational Journal of the Royal Society of Thailand.indd

The International Journal of the Royal Society of Thailand
Volume XV-2023

The First Licensed Malaria Vaccines: From RTS,S to R21

Borimas Hanboonkunupakarn , Podjanee Jittamala , Kittiyod Poovorawan ,
1,2
1,2
2,3
Kesinee Chotivanich 1,2,4 , Sasithon Pukrittayakamee 1,2,4 , Watcharapong Piyaphanee ,
1
Lorenz von Seidlein 2,5

Abstract

Currently two licensed malaria vaccines have been shown to be safe and
effective. The development of the first vaccine, RTS,S required about 30 years.
The second vaccine, R21, is a subunit malaria vaccine belonging to the same class

as RTS,S but with small changes in its molecular structure to improve the
immunogenicity. Data from a field trial in Burkina Faso showed that R21 with the
adjuvant Matrix-M (MM) is at least as safe and protective as RTS,S with the
adjuvant AS01. The production capacity of RTS,S/AS01 is limited to 10 million

doses annually. Considering the 3.3 billion people globally at risk for malaria and
the requirement for 4 doses to achieve lasting protection, RTS,S/AS01 is unlikely
to contribute to malaria elimination efforts globally. In contrast, the Serum Institute
of India is currently scaling up the production of R21/MM and has the capacity to

produce 100s of millions of doses R21/ MM annually. There is realistic hope that
R21/MM will play a key role in global malaria eradication efforts in the coming
years.

Keywords: malaria; vaccines; R21 matrix M; RTS,S; AS01 adjuvant; circum-sporozoite
protein; GSK; Serum Institute of India; Bill and Melinda Gates Foundation; WHO

1 Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok,
Thailand.
2 Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, Thailand
3 Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
4 Royal Society of Thailand.
5 Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
Correspondence to Lorenz von Seidlein (MD, PhD), Mahidol-Oxford Tropical Medicine Research Unit
(MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
Email: lorenz@tropmedres.ac

54 The First Licensed Malaria Vaccines: From RTS,S to R21