Why in news?

•  Sanofi Pasteur’s controversial vaccine dengvaxia has been approved by the US Food & Drug Administration, the first dengue vaccine to get the regulatory nod in the US.

Dengvaxia:

• Dengvaxia is basically a live, attenuated dengue virus.
• An attenuated virus is a virus that retains its properties of triggering an immune response in the body but its ability to lead to a disease is compromised.
• Three dengvaxia shots are administered, with the second and third given six and 12 months after the first one.
•  It was cleared in three randomised, placebo-controlled studies over approximately 35,000 individuals in dengue-endemic areas, including Puerto Rico, Latin America and the Asia Pacific region. It was found to be about 76% effective in 9-16-year-olds already exposed to the disease.  In Philippines 10 deaths were reported in the island nation in 2017 in the aftermath of a school vaccination campaign with dengvaxia
•  Dengvaxia is the first dengue vaccine to be licensed, Mexico being the first country to clear it in 2015. Subsequently it has been cleared in some 20 countries but what happened in 2017 in Philippines has raised question marks about CYD-TDV, as dengvaxia is known in technical parlance.

Issues with Dengvaxia:

•  Based on up to six years of clinical data, the analysis confirmed that Dengvaxia provides persistent protective benefit against dengue fever in those who had prior infection.
•  For those not previously infected by dengue virus, however, the analysis found that in the longer term, more cases of severe disease could occur following vaccination upon a subsequent dengue infection.

Use of Dengvaxia in India:

• Sanofi had submitted published data of Phase III trials from other countries and asked for a waiver
• In May 2017, India turned down a recommendation of the Subject Expert Committee of the Drug Controller General of India and told Sanofi that there could not be a waiver of the requirement that a drug or vaccine, before being allowed to be marketed in India, would have to undergo phase III clinical trials (that establish safety and efficacy of a drug) on Indian subjects.