Glossary · Public health
Contact tracing
Public health process of identifying, informing and following up people who have been in contact with a confirmed case of an infectious disease, to break transmission chains.
Contact tracing is a fundamental public health process that consists of identifying, informing and following up people who have been in contact with a confirmed case of an infectious disease, in order to break transmission chains. It is being applied in 10 countries for the passengers and crew of the MV Hondius, under joint WHO/ECDC international coordination.
Principle and purpose #
Three objectives #
Contact tracing pursues three simultaneous objectives: (1) early detection of contacts who develop symptoms, so they can be treated quickly and mortality limited; (2) breaking secondary transmission by isolating symptomatic contacts before they themselves become contagious; (3) documenting the outbreak to understand transmission chains and adjust measures.
Method #
The WHO distinguishes three steps: identification (listing contact persons through interviews with the case), enumeration (qualifying the nature and duration of contact) and follow-up (regular monitoring during the maximum incubation period, isolation if symptoms appear). This method is used for tuberculosis, measles, Ebola, COVID-19 and now Andes hantavirus.
Application to the MV Hondius #
Scope #
Authorities identified 149 people on board (passengers and crew) of 23 nationalities. Contact tracing is coordinated internationally by the WHO and ECDC, and operated by the national health authorities of each country of residence. As of 10 May 2026, 10 countries are running an active contact-tracing operation: Belgium, France, Greece, Ireland, Poland, Portugal, Spain, United States, Canada, Australia.
Surveillance duration #
Surveillance extends over 42 days from the last possible exposure, the maximum known incubation period for Andes virus. This duration is three times that used for COVID-19 (14 days), mobilising health resources for nearly a month and a half.
Individual instructions #
Identified contacts are asked to: monitor their temperature daily, seek care immediately if fever, headache or respiratory symptoms appear, and systematically mention their hantavirus exposure to their care provider. In France, 15 remains the emergency number; people can also contact their family doctor or their Regional Health Agency (ARS).
Legal and ethical framework #
Data protection #
In Europe, contact tracing is governed by the General Data Protection Regulation (GDPR). Health authorities only collect the information needed (identity, contact details, symptoms), for a strictly defined purpose (health follow-up), and destroy it at the end of the surveillance period. No data is shared for commercial or profiling purposes.
International cooperation #
The MV Hondius contact tracing illustrates the importance of the International Health Regulations (IHR 2005), the WHO legal framework that requires Member States to report events of international public health concern and to cooperate in managing them. The operation coordinated by the WHO and ECDC is an example of the IHR in action.
Key figures
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10
Countries involved in contact tracing for MV Hondius passengers (Belgium, France, Greece, Ireland, Poland, Portugal, Spain, United States, Canada, Australia).
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42 days
Duration of medical surveillance applied to MV Hondius passengers and contacts, matching the maximum incubation period of Andes virus.
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23
Nationalities on board the MV Hondius, requiring mobilisation of 10 national contact-tracing systems.
Standards & references
- WHO — Guideline on contact tracing — WHO operational guidelines on contact tracing for infectious diseases.
- ECDC — Public health management of contacts — European methodological framework for the public health management of people in contact with a case.
Frequently asked questions
What is contact tracing?
Contact tracing is one of the oldest tools of public health. It consists of reconstructing the list of people who were in contact with a confirmed case of an infectious disease during the contagious period, informing them of the risk, monitoring them to detect possible symptoms, and isolating or treating them if necessary. The goal is to break transmission chains.
How does it work for an MV Hondius case?
The health authorities of each passenger's country of residence identify and contact every person, ask them to monitor their temperature and symptoms for 42 days, provide them with a dedicated emergency phone number, and invite them to seek care without delay in case of suggestive signs (fever, headache, cough, shortness of breath). In France, this system is coordinated by the Regional Health Agencies (ARS) and Santé publique France (the French national public health agency).
Why 42 days and not 14 as for COVID-19?
The surveillance period matches the maximum known incubation period of the pathogen. For COVID-19 this was 14 days. For Andes virus, incubation can reach 42 days — three times longer — which requires extended monitoring of potentially exposed people.
Is my personal data protected?
Yes. Contact tracing is governed by the GDPR in Europe. Health authorities only retain information strictly necessary for follow-up and destroy it at the end of the surveillance period. No data is shared for commercial purposes.
Further reading
- WHO — Guideline on contact tracing — World Health Organization (official documentation)
- ECDC — Contact tracing public health management — ECDC (official documentation)
- Concepts of contact tracing — NCBI Bookshelf — NCBI (scientific publication)