# Andes hantavirus vaccine: where does research stand?

> No vaccine is licensed against Andes hantavirus. A DNA candidate cleared phase 1 successfully, but the efficacy trial hits one obstacle: too few patients.

Published on May 21, 2026 on HantaTracker
Canonical source: https://hantatracker.fr/en/articles/andes-hantavirus-vaccine-research-status/
Category: Médical

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The <a href="/en/glossary/mv-hondius/">MV Hondius</a> outbreak has brought a recurring question back to the fore&nbsp;: why, when vaccines were developed in record time against COVID-19, is there **still no vaccine** against Andes <a href="/en/glossary/hantavirus/">hantavirus</a>&nbsp;? The answer has less to do with science than with a hard-to-solve **epidemiological and economic** equation.

## No licensed vaccine against the Andes virus

Let us be clear from the outset&nbsp;: to date, **no vaccine is licensed** against the <a href="/en/glossary/andes-virus/">Andes virus</a>, nor more broadly against <a href="/en/glossary/hantavirus-pulmonary-syndrome/">hantavirus pulmonary syndrome</a> (HPS), whether in the United States, Europe or Latin America.

This absence may surprise, because hantavirus vaccines **do exist**… but elsewhere, and against other viruses. In **South Korea**, the inactivated **Hantavax** vaccine has been used for decades. In **China**, inactivated vaccines (rodent-brain-derived and, more recently, cell-culture-derived) are administered on a large scale. But these vaccines target the **Hantaan** and **Seoul** viruses, responsible in Asia and Europe for <a href="/en/glossary/hfrs/">haemorrhagic fever with renal syndrome</a> (HFRS) — a disease distinct from American HPS. They **do not protect** against the Andes virus.

## A DNA candidate that proved itself… in phase 1

Research is not at a standstill, however. The most advanced candidate against the Andes virus is a **DNA vaccine** developed by **USAMRIID**, the US Army's medical research institute of infectious diseases (Fort Detrick, Maryland).

Its principle&nbsp;: have the body produce the virus's two **envelope glycoproteins** (Gn and Gc), training the immune system to recognise them. The **phase 1** study, published in 2024, delivered encouraging results&nbsp;:

- **48 healthy adults**, split into four cohorts (2 or 4&nbsp;mg doses, 3- or 4-injection schedules)&nbsp;;
- **needle-free** administration, by pressure injection (PharmaJet Stratis system)&nbsp;;
- **88 to 90%** of participants in the best-dosed cohorts developed **neutralising antibodies** (67% in the lowest-dose cohort)&nbsp;;
- the authors' conclusion&nbsp;: a "**safe**" vaccine inducing a "**robust and durable**" immune response.

It is a real milestone — but a phase 1 only measures **safety** and **immune response**, not actual efficacy in **preventing disease**. And that is exactly where the road stalls.

## The real obstacle: not enough patients to prove it works

To license a vaccine, you need a **phase 3**&nbsp;: demonstrating, across a large population, that the vaccinated fall significantly less ill than the unvaccinated. But HPS is a **rare, sporadic** disease. The Andes virus causes a few hundred cases a year, scattered across vast rural areas of South America.

As a result, to observe enough cases and prove efficacy, you would need to **enrol tens of thousands of people** in at-risk regions — typically Patagonia — and **follow them for years**. Such a trial is logistically heavy and very costly, for a narrow commercial market. That was the analysis summed up by *Der Spiegel* on 18 May 2026 under a telling headline&nbsp;: how lack of money **and lack of patients** are slowing development.

In other words&nbsp;: it is not that science cannot make a vaccine — it is that proving it works is very hard, for want of enough patients to protect.

## What the MV Hondius episode could change

A high-profile outbreak like the MV Hondius can **reshuffle the deck** by reviving scientific interest and funding. Several avenues remain open&nbsp;: optimising the DNA candidate, **nucleic-acid** platforms (including messenger RNA) being explored against hantaviruses, and work carried out notably in **Argentina**, where hospital teams have for years been seeking a vaccine suited to South American strains (France Info, 21 May 2026).

But perspective is in order&nbsp;: no licensed product is expected in the **short term**. For now, prevention rests on what already works — avoiding exposure to <a href="/en/glossary/rodent-reservoirs/">reservoir rodents</a> and their droppings, and applying strict protocols in case of contamination.

## What about treatment?

The picture is similar on the therapeutic side&nbsp;: there is **no licensed specific antiviral** against HPS. Care remains **supportive** — respiratory support and, in severe forms, <a href="/en/glossary/ecmo/">ECMO</a> (extracorporeal membrane oxygenation), as for the French patient hospitalised at Bichat. Hence the importance of **early diagnosis** and of monitoring exposed people throughout the <a href="/en/glossary/incubation-period/">incubation period</a>.

## Key takeaways

- **No licensed vaccine** against Andes hantavirus / HPS, in the Americas or Europe.
- Existing vaccines (**Hantavax** in Korea, inactivated vaccines in China) target **other strains** (Asian HFRS), not the Andes virus.
- A **USAMRIID DNA candidate** cleared **phase 1** (88-90% neutralising-antibody responders, safety confirmed).
- The bottleneck is **logistical and economic**: the disease is too rare for a realistic phase 3 efficacy trial.
- No vaccine expected in the **short term**; prevention rests on rodent avoidance and <a href="/en/glossary/ppe/">PPE</a>/disinfection protocols.

For the disease and its management, see [Andes virus in depth](/en/articles/andes-virus-deep/). On decontamination after exposure, read [why you wet surfaces instead of sweeping](/en/articles/hantavirus-decontamination-why-wet-cleaning/).