Quick answer
Hantavirus CFR ranges from under 1% (HFRS from Puumala) to roughly 30–40% (HPS from Andes or Sin Nombre virus). It is not a single number: it depends on virus type, syndrome (HPS or HFRS), ICU access and how cases are defined. With no specific antiviral licensed, early supportive care is the main modifiable factor.
What CFR means
Case fatality rate (CFR) is the proportion of people with a confirmed infection who die from the disease. It is usually expressed as a percentage. CFR measures lethality once a case is diagnosed, and it depends heavily on how cases are defined and counted.
If surveillance only detects severe cases, CFR looks high. If surveillance also detects mild or asymptomatic cases (through serology, for example), CFR tends to be lower. That is why reported hantavirus CFR can differ across countries even when the underlying virus is the same.
CFR vs mortality rate vs death rate
These terms are different. CFR is calculated among confirmed cases. Mortality rate usually refers to deaths per unit of population over time (for example, per 100,000 people per year). The phrase "death rate" is used loosely in the media for both, so it is worth checking the underlying source.
Hantavirus is a clear example: HPS CFR can be high, yet global population-level mortality from hantavirus is low because the disease itself is rare. Mixing the two numbers can give a very distorted picture of real-world risk.
HPS vs HFRS comparison
The two main syndromes caused by hantaviruses have different CFR profiles:
HPS — Americas
~30–40%- Strains: Sin Nombre, Andes
- Cardiopulmonary syndrome
- Rapid progression
- High CFR even with ICU
HFRS — Europe / Asia
< 1 – 15%- Strains: Puumala, Hantaan, Dobrava, Seoul
- Renal syndrome
- More gradual progression
- CFR varies strongly by strain
CFR by virus type and syndrome
| Syndrome / Virus | Region | Approx. CFR | Notes | Source |
|---|---|---|---|---|
| HPS / HCPS | Americas (broad) | ~30–40% | Pulmonary syndrome group; severity depends on strain and ICU access. | CDC, PAHO |
| Andes virus | Argentina / Chile | ~35–40% | Only hantavirus type known to spread person-to-person in close contacts. | WHO, PAHO |
| Sin Nombre virus | USA / Canada | ~36% | Historical CDC HPS surveillance; deer mouse reservoir. | CDC |
| HFRS (group) | Asia / Europe | <1% – 15% | Wide range driven by virus type and case definition. | WHO, ECDC |
| Puumala virus | Northern Europe | <0.5% | Nephropathia epidemica; usually mild. | ECDC |
| Dobrava-Belgrade virus | Balkans / SE Europe | ~5–12% | CFR varies markedly by sub-lineage. | ECDC |
| Seoul virus | Global (commensal rat) | <1% | Distributed worldwide via Rattus norvegicus. | WHO, CDC |
Ranges are based on published estimates and official summaries from WHO, CDC, ECDC and PAHO. CFR observed in small outbreaks may fall outside these ranges due to statistical noise.
Why CFR varies
- Virus: Sin Nombre and Andes are more virulent than Puumala or Seoul.
- ICU access: Early admission before the cardiopulmonary phase clearly improves survival in HPS.
- Underlying health: Cardiovascular and renal disease worsen prognosis.
- Case definition: Narrow definitions that capture only severe cases inflate CFR.
- Outbreak size: Small outbreaks produce unstable percentages. CFR observed in a handful of cases is not generalisable.
2026 context
In 2026 attention has focused on the MV Hondius outbreak (Andes virus), with ECDC and WHO reporting confirmed and probable cases and 42-day monitoring of contacts. Published CFR ranges from WHO, CDC and ECDC for HPS and HFRS have not changed; individual outbreaks may show higher or lower observed CFRs, but do not redefine the global ranges.
Hantavirus CFR — Frequently Asked Questions
What is the CFR of hantavirus?
There is no single CFR for hantavirus. Case fatality rate ranges from below 1% for Puumala virus HFRS in northern Europe to roughly 30–40% for HPS caused by Sin Nombre or Andes virus in the Americas. The wide range reflects different viruses, different syndromes, and different healthcare contexts (WHO, CDC, ECDC).
What does CFR mean?
CFR stands for case fatality rate. It is the proportion of people with a confirmed infection who die from the disease, typically expressed as a percentage. CFR depends heavily on how cases are defined and counted — broader testing and surveillance often lower CFR, because milder cases get included in the denominator.
What is the difference between CFR and mortality rate?
CFR measures the lethality of a disease once diagnosed: deaths divided by confirmed cases. Mortality rate usually means deaths per unit of population over time (for example, per 100,000 people per year). Hantavirus has a high CFR in some strains but a low overall mortality rate worldwide because the disease itself is rare.
Is hantavirus CFR higher in HPS or HFRS?
HPS (Hantavirus Pulmonary Syndrome), caused by Sin Nombre or Andes virus, has a higher CFR than most HFRS variants. HPS CFR is typically around 30–40%. HFRS CFR ranges from below 0.5% (Puumala) to 5–15% (Hantaan, Dobrava). HFRS is more common globally but generally less lethal per case.
Why do hantavirus fatality rates vary so much?
CFR varies because of (1) the virus itself — Sin Nombre and Andes are more virulent than Puumala or Seoul; (2) speed of access to ICU care; (3) underlying patient health, especially cardiovascular and renal conditions; (4) how cases are defined — narrow definitions that capture only severe cases inflate CFR; and (5) outbreak size — small outbreaks generate unstable percentages.
Is Andes virus more deadly than other hantaviruses?
Andes virus has a case fatality rate of roughly 35–40%, comparable to Sin Nombre virus, placing it among the deadliest hantaviruses. It is also the only hantavirus type known to spread person-to-person, although this is uncommon and typically limited to close contacts.
Does early treatment reduce hantavirus CFR?
Yes. Early hospital admission and intensive supportive care — fluid management, ventilation, ECMO in severe HPS — are consistently associated with better outcomes. There is no specific antiviral licensed for hantavirus, so supportive care is the main lever for improving survival (CDC, PAHO).
Medical disclaimer: This page is for informational purposes only and does not constitute medical advice. CFR ranges reflect published estimates and official summaries from WHO, CDC, ECDC and PAHO. Anyone with symptoms after rodent exposure should consult a doctor.