The study stated that almost 30,000 swine had been monitored via nasal swabs between 2011 and 2018. While other variants of the virus have appeared and diminished, the study claimed the G4 variant had sharply increased since 2016 to become the predominant strain. The Chinese Ministry of Agriculture and Rural Affairs rebutted the study, saying that the number of pigs sampled was too small to demonstrate G4 had become the dominant strain and that the media had interpreted the study "in an exaggerated and nonfactual way". They also said the infected workers "did not show flu symptoms and the test sample is not representative of the pig population in China".