Scientific Opinion on the pandemic (H1N1) 2009 influenza and its potential implications for animal health

Pandemic H1N1, pigs, poultry, turkey, vaccines, control measures, virus evolution
First published in the EFSA Journal
4 October 2010
9 September 2010
Last Updated
15 November 2010. This version replaces the previous one/s.
Scientific Opinion

Analysis of the recent pandemic (H1N1) 2009 (pH1N1) virus indicates a probable origin in pigs. However, it was not reported in pigs prior to its detection in humans. Several cases of pH1N1 virus infections in animals have been reported, mainly in pigs but also in other animals including turkeys. Occasionally, pigs have been infected following exposure to pH1N1 infected humans. In pigs, a subclinical course was common and when clinical signs were seen (coughing, fever) they were generally mild. Presently, the clinical impact of pH1N1virus on the EU pig population is considered minimal. In poultry, outbreaks of pH1N1 have been reported only in turkey breeder flocks. So far, there is no evidence that pH1N1 virus is able to spread horizontally among turkeys. Awareness should be raised about the risk of infecting breeder turkeys with pH1N1 virus during artificial insemination. To date, no infection of wild birds with pH1N1 virus has been reported. From an animal health perspective, no specific disease control measures are considered necessary. Vaccines based on the pH1N1 virus appear to induce protection in swine similar to that induced by the existing swine influenza virus (SIV) vaccines. Such vaccines efficiently prevent disease by reducing virus replication in the lungs. However, voluntary vaccination of swine with these vaccines has not halted the circulation of SIV in swine. There is no urgency for vaccination of pigs against pH1N1 virus. Currently, no vaccines against H1 viruses for poultry are available but at present, there is no need to vaccinate poultry against pH1N1 virus. Monitoring of circulating influenza viruses in swine and poultry populations should be instigated to monitor the evolution of the pH1N1 virus including changes in virulence.

Panel members at the time of adoption
Anette Bøtner, Donald M. Broom, Marcus G. Doherr, Mariano Domingo, Joerg Hartung, Linda Keeling, Frank Koenen, Simon More, David Morton, Pascal Oltenacu, Albert Osterhaus, Fulvio Salati, Mo Salman, Moez Sanaa, James Michael Sharp, Jan Arend Stegeman, Endre Szücs, Hans-Hermann Thulke, Philippe Vannier, Anthony John Webster, Martin Wierup
Panel on Animal Health and Welfare
ahaw [at]
EFSA Journal 2010;8(10):1770
Question Number
On request from
European Commission