Bangladesh’s success in maintaining its polio-free status is a result of continuous research, effective vaccination strategies, and international collaboration [1]. The nation’s role in the fight against polio is a shining example of how dedication and innovation can help combat vaccine-preventable diseases, transcending political and geographical differences.

In a recent interview with The Daily Star, Dr. Md Khalequzzaman, a senior scientist and epidemiologist at icddr,b, shared his insights on the fight against the poliovirus and Bangladesh’s significant contribution to poliovirus vaccine research. This reflection blog takes a closer look at how Bangladesh has successfully maintained its polio-free status.

Dr. Khalequzzaman highlighted the remarkable progress in the global fight against polio. Wild poliovirus types 2 and 3 were declared eradicated in 2015 and 2019, leaving only two countries, Pakistan and Afghanistan, with sporadic cases. In Bangladesh, the last recorded polio case was in 2006. This success story makes Bangladesh a key player in the global polio awareness and vaccination drive.

One of the critical elements in the fight against polio has been the introduction of vaccines. The first poliovirus vaccine was licensed in the United States back in 1955, followed by the development of the oral poliovirus vaccine (OPV) in the early 1960s. OPV became the primary choice for vaccination in many countries due to its cost-effectiveness and ease of administration.

However, OPV does have disadvantages, primarily due to the live attenuated viruses it contains. In some rare cases, these live viruses can mutate in the human body, leading to vaccine-associated paralytic polio (VAPP). Additionally, the virus can circulate in areas with inadequate vaccination coverage, resulting in the emergence of new variants of poliovirus, known as circulating vaccine-derived polioviruses (cVDPVs). So, while OPV has played a crucial role in reducing polio cases worldwide, it also played a part in the emergence of new polio variants. 

The icddr,b has been instrumental in Bangladesh’s efforts to combat polio. They have conducted numerous polio vaccine trials that have had a global impact. One significant study found that a 2-week interval between OPV doses was as effective as the traditional 4-week schedule. This adjustment simplified vaccine administration, especially in rural areas with logistical challenges.

Furthermore, icddr,b’s research revealed that monovalent type 2 OPV (mOPV2) could be administered at shorter intervals without affecting its effectiveness, a finding that received recognition from the CDC. Their studies also supported the use of fractional Inactivated Poliovirus Vaccine (IPV) at reduced doses and shorter intervals, addressing the global IPV shortage issue.

In addition to these findings, icddr,b played a pivotal role in the development and testing of a novel type 2 OPV (nOPV2) that has proven to be genetically stable and safe for newborns. The results of their study showed that nearly 99% of infants developed protective antibodies after receiving the nOPV2, making it a valuable tool in outbreak responses.

While Bangladesh has been successful in preventing polio, being geographically close to Pakistan and Afghanistan does pose some risks. Dr. Khalequzzaman emphasised the importance of continued vigilance through surveillance to detect and prevent any potential outbreaks.

In his role as a member of the WHO Polio Research Committee and the Polio WHO Strategic Advisory Group of Experts, Dr. Khalequzzaman highlighted the need for ongoing efforts to ensure polio remains a disease of the past. The collaboration of various institutions, scientists, governments, and international organisations has been instrumental in this fight. While there are logistical and political challenges, the situation is gradually improving.

Support from the Government of Bangladesh (GoB) and contributions from organisations like icddr,b have made a significant impact. Their studies and strategies have not only kept Bangladesh polio-free but also benefited people around the world. With the ongoing commitment of governments, organisations, and scientists, we can hope that polio will soon join the eradicated status akin to smallpox and rinderpest as diseases are eliminated from the world.

References:

• Anwar HB, Mazumder Y, Nujhat S, Islam BZ, Kalbarczyk A, Alonge OO, et al. Acute Flaccid Paralysis surveillance in polio eradication and beyond: Learning from Bangladesh [Internet]. Research Square. 2022 [cited 2023 Dec 18]. Available from: https://www.researchsquare.com/article/rs-680893/latest
• Alvi NA. “Our studies helped countless people all over the world” [Internet]. The Daily Star. 2023 [cited 2023 Nov 20]. Available from: https://www.thedailystar.net/opinion/views/interviews/news/our-studies-helped-countless-people-all-over-the-world-3451791