# Vaccine

> A preparation that trains the immune system to recognise a pathogen. Against Andes hantavirus, no vaccine is licensed to date.

Canonical source: https://hantatracker.fr/en/glossary/vaccine/

**Aliases**: vaccination, DNA vaccine, inactivated vaccine, Hantavax, hantavirus vaccine

A **vaccine** is a biological preparation that trains the immune system to recognise a pathogen so it can defend against it on real exposure. Against [hantavirus](/en/glossary/hantavirus/), the picture is mixed: vaccines exist in Asia against certain strains, but **none is licensed against the [Andes virus](/en/glossary/andes-virus/)**, the cause of the MV Hondius cluster.

## Existing hantavirus vaccines

### In Asia, against other strains

In **South Korea**, the inactivated **Hantavax** vaccine has been used for decades. In **China**, inactivated vaccines (rodent-brain-derived, then cell-culture-derived) are administered on a large scale — about two million doses a year. But these vaccines target the **Hantaan** and **Seoul** viruses, responsible for [haemorrhagic fever with renal syndrome](/en/glossary/hfrs/) (HFRS), and **do not protect** against the Andes virus.

### No vaccine for pulmonary syndrome

For [hantavirus pulmonary syndrome](/en/glossary/hantavirus-pulmonary-syndrome/) (HPS), the American form of the disease, there is **no licensed vaccine** to date.

## The Andes virus DNA candidate

The most advanced candidate is a **DNA vaccine** developed by **USAMRIID** (the US Army's medical research institute of infectious diseases). Its principle: have the body produce the virus's **envelope glycoproteins** Gn and Gc, to train the immune response.

The **phase 1** trial, published in 2024, involved **48 healthy adults**, with **needle-free** administration (PharmaJet Stratis system). Result: **88 to 90%** of participants in the best-dosed cohorts developed neutralising antibodies, with no safety signal. But a phase 1 only measures safety and immune response — not actual efficacy in preventing disease.

## The phase 3 bottleneck

To license a vaccine, you need a **phase 3** demonstrating its efficacy across a large population. But HPS is too **rare and sporadic**: such a trial would require enrolling tens of thousands of people in at-risk areas and following them for years. That is the main obstacle, both logistical and economic — and the reason why, despite promising candidates, no vaccine is expected in the short term.

For more, see our article [where does Andes hantavirus vaccine research stand?](/en/articles/andes-hantavirus-vaccine-research-status/).