India's first dengue vaccine

LeadPrelims and MainsJuly 2026

Why in news

The Central Drugs Standard Control Organisation granted marketing authorisation to Qdenga in July 2026, the first dengue vaccine approved in India, for people aged 4 to 60.

Background

Dengue is a viral disease spread by the Aedes aegypti mosquito, which bites by day and breeds in clean standing water.
The virus has four serotypes, DENV-1 to DENV-4. Infection with one gives lasting protection against that one, and only brief protection against the others.
A second infection by a different serotype is often more severe than the first.
India carries close to a third of the world's dengue burden.

Why dengue vaccines are hard to make

Antibodies from a first infection can help a different serotype enter cells in a second infection. This is antibody dependent enhancement.
So a vaccine must protect against all four serotypes equally. Partial protection can leave a person worse off than no vaccine.
An earlier vaccine could be given safely only to people who had already had dengue, which meant testing before vaccination.

How antibody dependent enhancement works across the four dengue serotypes, and what Qdenga protects against.Source: Press Information Bureau, 21 July 2026; The Hindu, July 2026

The vaccine

Qdenga is a live attenuated tetravalent vaccine, built on a dengue type 2 backbone.
It is given as two doses, three months apart, and needs no test for earlier infection.
In trials it was about 80 per cent effective against confirmed dengue and about 90 per cent against hospitalisation.
The caveat: in people who have never had dengue, protection is shown only against DENV-1 and DENV-2, which raises a concern about later disease from DENV-3.
It is not part of the Universal Immunisation Programme.

All four serotypes, together

A national study found all four serotypes circulating together in eight States and Union Territories, a state called hyperendemicity.
DENV-2 was the most common.
About 7 per cent of patients carried two or more serotypes at once, and were more likely to develop severe dengue.
Which serotype circulates decides how well the vaccine works, so surveillance has to continue alongside it.

The way forward

Keep serotype surveillance running, and watch vaccinated children for later severe disease.
Decide on a public programme only with Indian data on safety in those never infected.
Continue mosquito control, since no vaccine removes the need for it.
Support the indigenous vaccine candidates now in trials.

Prelims facts

Dengue has four serotypes; the vector is Aedes aegypti.
Qdenga: live attenuated, tetravalent, two doses, ages 4 to 60, no test before vaccination.
It is built on a DENV-2 backbone.
Approval in India comes from the Central Drugs Standard Control Organisation.