Experimental and field investigations of exposure, replication and transmission of SARS-CoV-2 in pigs in the Netherlands

Reina S Sikkema, Tijs Tobias, Nadia Oreshkova, Erwin de Bruin, Nisreen Okba, Felicity Chandler, Marcel M Hulst, Jordi Rodon, Manon Houben, Kees van Maanen, Hans Bultman, Marina Meester, Nora M Gerhards, Martijn Bouwknegt, Bert Urlings, Bart Haagmans, Jan Kluytmans, Corine H Geurtsvan Kessel, Wim H M van der Poel, Marion P G KoopmansArjan Stegeman

Research output: Contribution to journalArticleAcademicpeer-review


In order to assess the risk of SARS-CoV-2 infection, transmission and reservoir development in swine, we combined results of an experimental and two observational studies. First, intranasal and intratracheal challenge of eight pigs did not result in infection, based on clinical signs and PCR on swab and lung tissue samples. Two serum samples returned a low positive result in virus neutralization, in line with findings in other infection experiments in pigs. Next, a retrospective observational study was performed in the Netherlands in the spring of 2020. Serum samples (N =417) obtained at slaughter from 17 farms located in a region with a high human case incidence in the first wave of the pandemic. Samples were tested with protein micro array, plaque reduction neutralization test and receptor-binding-domain ELISA. None of the serum samples was positive in all three assays, although six samples from one farm returned a low positive result in PRNT (titers 40–80). Therefore we conclude that serological evidence for large scale transmission was not observed. Finally, an outbreak of respiratory disease in pigs on one farm, coinciding with recent exposure to SARS-CoV-2 infected animal caretakers, was investigated. Tonsil swabs and paired serum samples were tested. No evidence for infection with SARS-CoV-2 was found. In conclusion, Although in both the experimental and the observational study few samples returned low antibody titer results in PRNT infection with SARS-CoV-2 was not confirmed. It was concluded that sporadic infections in the field cannot be excluded, but large-scale SARS-CoV-2 transmission among pigs is unlikely.

Original languageEnglish
Pages (from-to)91-94
Number of pages4
JournalEmerging Microbes and Infections
Issue number1
Early online date29 Nov 2021
Publication statusPublished - 2022


  • Coronavirus
  • One Health
  • SARS-CoV-2
  • Swine
  • antibody


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