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| Relevance: GS Paper III — Science & Technology, Biotechnology & Health | Source: News reports, June 2026 |
1 · What happened
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On 8 June 2026, Brazil temporarily paused its dengue vaccination campaign that used a vaccine called Butantan-DV. The pause came after 42 people who had taken the vaccine fell seriously ill — with strong stomach pain, repeated vomiting, and bleeding. Sadly, two of them died and one needed intensive care. It is important to be careful here. The government called this a safety precaution, not a verdict. Nearly 5 lakh (500,000) people had been vaccinated, so these 42 cases are a very tiny share (about 0.008%), and so far there is no proof that the vaccine actually caused the deaths. Yet this news matters a lot for us, because India’s own upcoming dengue vaccine, DengiAll, is built on nearly the same technology as Butantan-DV. |
2 · The big worry, explained simply — ADE
| First, the basics: dengue is caused by a virus that comes in four versions, called serotypes — DENV-1, 2, 3 and 4. Beating one version does not protect you from the other three. This single fact is why dengue is so hard to vaccinate against — and it sets up a strange danger called ADE, shown step by step below. |
| 1 |
The body builds its defenders
After a dengue infection or a dengue vaccine, the body makes antibodies — tiny defenders that learn to catch and stop the virus.
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| 2 |
Their strength slowly fades
As months pass, these antibodies fall in number and grow weak. They are still in the body, but no longer strong enough to fully stop a fresh attack.
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| 3 |
A different dengue strikes
Later, the person catches a different serotype of dengue. The weak leftover antibodies rush in and grab on to this new virus.
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| 4 |
The enemy is let inside
But they are too weak to kill it. Instead, they carry the virus into the body’s own cells — like opening the gate for an enemy. The virus now spreads even faster.
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| 5 |
Dengue turns severe
The illness becomes far more dangerous, sometimes deadly. This whole effect — where weak old protection makes a new infection worse — is called Antibody-Dependent Enhancement (ADE).
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- Why one dengue vaccine is so hard to make: A safe vaccine must protect against all four serotypes equally. Such vaccines mix four weakened virus types into a single shot — they are called “tetravalent” vaccines. The fear is “interference”: one type may overpower the others, leaving uneven protection that can later trigger ADE.
- This was not an untested vaccine: Butantan-DV was approved in Brazil in late 2025 after trials on over 11,000 volunteers, showing about 65% protection against dengue and 80.5% against severe dengue. The rare reactions appeared only later, after public use began — which is exactly why monitoring must continue even after approval.
- The four vaccines worth remembering:
- DengiAll — India’s vaccine; built on US NIH technology, licensed to Panacea Biotec; in late-stage (Phase-3) trials with ICMR.
- Butantan-DV — Brazil’s vaccine, on the same platform as DengiAll; now paused.
- Dengvaxia — by Sanofi; ran into trouble in the Philippines as it raised severe-dengue risk in people who had never had dengue before.
- Qdenga — by Takeda (Japan); another tetravalent vaccine being looked at for India.
- The way ahead for India: Before clearing DengiAll, the drug regulator CDSCO and ICMR should insist on careful blood-sample testing to confirm equal protection against all four types, and build a strong pharmacovigilance system — that is, long-term tracking of vaccinated people to catch any late side effects early.
| UPSC Value Box | ||||||||||||||||||||||||
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| MCQ Practice Question |
Q. With reference to dengue and dengue vaccines, consider the following statements:
Which of the statements given above is/are correct? |
Answer: (c) 1 and 3 only
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