Hantaviruses are agents whose natural reservoir includes various species of rodents. Humans are infected mainly by inhalation of dust contaminated with fluids (saliva, urine, faeces) of these rodents or, more rarely, by bite or gastrointestinal infection. Human infection includes asymptomatic cases, purely febrile clinical pictures and haemorrhagic presentations with renal syndrome. In France, most hantavirus infections - observed essentially in the north-eastern quarter of metropolitan France (if we exclude the few cases of Maripa virus infection that have recently occurred in French Guiana) - are due to the Puumala species, for which human-to-human contamination is exceptional.

Following the start of a hantavirus epidemic by the Puumala species in the departments of Jura and Doubs in March-April 2021, for which precautionary measures for blood donations had been set up, the High Council for Public Health (HCSP) was asked by the General Directorate for Health to obtain an expert opinion on the measures that were taken and also on the potential risks due to hantaviruses for donations of products derived from the human body.

On the basis of a review of the literature and of French and European epidemiological data, this opinion details the different types of hantavirus that are responsible of pathologies in humans and their circulation in the world, the frequency of infections linked to these viruses as well as their modes of transmission, in particular in the context of donations of blood or other products from human origin.

Given:

• the very low number of reports having related transmission of Puumala virus through blood donation,
• the modelling of this risk updated by Santé publique France and the National Reference Centre (CNR) for hantaviruses at the Pasteur Institute of Paris,
• the non consideration of this risk in European countries (Finland, Sweden, Germany, Austria, etc.) that are much more affected yearly by Puumala virus outbreaks,
• and the deleterious consequences on blood product stocks if exclusion measures were to be taken both on the national territory and for travellers returning from endemic areas,

the HCSP recommends:

• not to evict donors of products from human origin in the context of a Puumala virus epidemic;
• to reinforce post-donation information in exposed areas;
• to continue the epidemiological monitoring in partnership with the CNR for hantaviruses and the European health authorities, with the aim to better define the pathophysiology of the hantavirus infection.