First Malaria Vaccine: Mosquirix

• 07 Oct 2021

Why in News

Recently, the World Health Organisation (WHO) endorsed the world's first Malaria Vaccine in the hope that it will spur stalled efforts to curb the spread of the parasitic disease.

• Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. It is preventable and curable.

Key Points

• About:
  • RTS,S/AS01, trade name Mosquirix, is an injectable vaccine targeting P. falciparum, the most prevalent malaria strain in Africa. It is the first and only vaccine to show partial protection in young children.
    
    • It was developed by British drugmaker GlaxoSmithKline in 1987.
  • The active substance in Mosquirix is made up of proteins found on the surface of the Plasmodium falciparum parasites (PFP).
    • RTS,S aims to trigger the immune system to defend against the first stages of malaria when the PFP enters the human host’s bloodstream through a mosquito bite and infects liver cells.
  • It also helps protect against infection of the liver with the Hepatitis B virus.
• Potency:
  • The vaccine's effectiveness at preventing severe cases of malaria in children is only around 30%, but it is the only approved vaccine.
    • The European Union's drugs regulator approved it in 2015, saying its benefits outweighed the risks.
  • Its side effects are rare, but sometimes include a fever that may result in temporary convulsions.
• Challenges:
  • Inconvenient: A child must receive four injections before age 2, sometimes at intervals that do not match the routine vaccine schedules for most other diseases.
  • Partly Effective: Testing in more than 10,000 African children from 2009 to 2014 showed that, even after four doses, the vaccine prevented only about 40% of detectable malaria infections.
  • Not Long Lasting: It is unclear how long even those relatively low levels of protection last; previous trials followed vaccinated children for four years. Experts also worry that parents whose children are vaccinated will become less vigilant about using mosquito nets, and less likely to seek medical care when their children develop fevers.
  • Develop Resistance: The vaccine reduced the occurrence of severe malaria by about 30%, and the occurrence of severe anemia - a complication that often kills children - by about 60%. It did not protect well against parasite strains that were poor genetic matches, raising a concern that, over time, parasites could evolve resistance to the vaccine as they have to drugs.
• Burden of Malaria:
  • Global:
    • In 2019, there were an estimated 229 million cases of malaria worldwide, and the estimated number of malaria deaths that year stood at 4,09,000.
      • Children aged under 5 years are the most vulnerable group affected by malaria in 2019, they accounted for 67% (2,74,000) of all malaria deaths worldwide.
  • India:
    • In 2019, India had an estimated 5.6 million cases of malaria compared to about 20 million cases in 2020, according to WHO.
• Countries that Eliminated Malaria:
  • Over the last two decades, 11 countries have been certified by the WHO Director-General as malaria-free: United Arab Emirates (2007), Morocco (2010), Turkmenistan (2010), Armenia (2011), Sri Lanka (2016), Kyrgyzstan (2016), Paraguay (2018), Uzbekistan (2018), Algeria (2019), Argentina (2019), and El Salvador (2021).
    • Countries that have achieved at least 3 consecutive years of zero indigenous cases of malaria are eligible to apply for the WHO certification of malaria elimination.

Way Forward

The next steps for the WHO-recommended malaria vaccine will include funding decisions from the global health community for broader rollout in endemic countries, and country decision-making on whether to adopt the vaccine as part of national malaria control strategies.

Source: IE