Short answer
Andes virus is the only hantavirus that official sources describe as spreading person-to-person. That spread requires close contact with a sick person. Official sources including WHO, ECDC, and CDC consistently describe this as limited human-to-human transmission, not broad casual public spread.
How close-contact transmission occurs
Official sources link Andes virus person-to-person transmission to direct physical contact with a sick person, prolonged time indoors in close or enclosed spaces with a symptomatic person, and exposure to body fluids. CDC notes this is consistent with contact and droplet precautions rather than the airborne spread that would enable casual transmission. The specific settings in which confirmed person-to-person transmission has occurred include household exposure, intimate partner contact, and close shared accommodations.
High-risk contact scenarios
- Intimate partners or household members of a confirmed Andes virus case
- People who shared a cabin or sleeping space on the same vessel as a confirmed case
- Prolonged close indoor exposure during the period when a case was symptomatic
- Healthcare workers who had unprotected close contact with a suspected or confirmed case
Lower-risk exposure — brief transit through a shared space, proximity without prolonged close contact, or short interactions in large open areas — does not carry the same classification as household or cabin-sharing exposure. Public-health authorities determine risk categories based on the specific contact details.
WHO contact definitions and monitoring
WHO DON601 describes two contact tiers. High-risk contacts are people who had close prolonged contact with a confirmed case during the symptomatic period, including household members, intimate partners, and unprotected healthcare workers. Low-risk contacts are people with less direct exposure, such as those who shared common spaces without prolonged close proximity.
WHO recommends that high-risk contacts undergo active monitoring and home or facility quarantine for 42 days from last exposure, with daily symptom assessment and immediate evaluation if symptoms develop. Low-risk contacts should self-monitor for symptoms and seek evaluation if they appear, without required quarantine.
The 42-day monitoring window
The 42-day period for high-risk contacts is derived from the maximum documented incubation period for Andes virus HPS, which CDC states is 4 to 42 days. Monitoring for the full maximum incubation window ensures that any case developing at the outer edge of the distribution is identified. The hantavirus incubation period page explains the full range and its sources.
Infection control for caregivers
WHO guidance for healthcare workers and household caregivers managing Andes virus cases recommends standard precautions plus contact and droplet precautions. Practical steps include wearing gloves when in contact with body fluids, wearing a gown when body fluid contact is likely, using respiratory protection when performing procedures that might generate aerosols, maintaining good hand hygiene, and not sharing personal items with the ill person. These precautions are aligned with the contact and droplet transmission characteristics described in official sources.
What official risk assessments say
WHO, ECDC, and CDC have each published risk assessments for the 2026 Andes virus outbreak. All describe the risk to the general public as low, very low, or extremely low. This assessment reflects the transmission biology: Andes virus requires close contact, not incidental or casual proximity, to spread between people. People not identified as high-risk contacts by public-health authorities are not subject to active quarantine under current guidance.
Sources reviewed for this page
Frequently asked questions
Does Andes virus spread before symptoms appear?
WHO states that pre-symptomatic transmission cannot be entirely ruled out and recommends precautionary monitoring for high-risk contacts as a result. Most documented person-to-person cases involve symptomatic contact, which is why the monitoring window for high-risk contacts extends to 42 days from last exposure.
Is casual public spread expected from this outbreak?
No. Current official risk assessments from WHO, ECDC, and CDC describe broad public risk as low, very low, or extremely low. Official sources consistently note that Andes virus requires close contact — not casual proximity — to spread between people. Community spread in the general public has not been described.
Why is the monitoring or quarantine period 42 days?
The 42-day period is derived from the maximum documented incubation period for Andes virus HPS. CDC states that signs and symptoms can appear 4 to 42 days after exposure. Monitoring for the full maximum ensures that any case developing at the outer edge of the distribution is identified before the quarantine ends.
Do I need to be tested if I am a close contact?
WHO DON601 says current evidence does not support routine laboratory testing of contacts for outbreak control. Testing is a clinical decision made based on whether symptoms develop. If you are identified as a high-risk contact by public-health authorities, follow their instructions; those instructions will specify whether and when testing should be sought.
Can I end isolation early if I test negative?
A negative test very early in the monitoring period does not rule out future infection, because antibody levels may not yet be detectable. Isolation or quarantine decisions for high-risk contacts are made by public-health authorities, not by a single early test result. Follow official instructions for the full duration specified.
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Report a correctionPrimary sources reviewed
CDC, WHO, and ECDC official public-health pages were reviewed for this build. Current outbreak counts use official outbreak updates; evergreen pages use official background and guidance pages.