A group of scientists from the National Health Research Institutes in Taiwan set out to study how methamphetamine interacts with influenza A virus in lung cells. Previous research has suggested that chronic meth abuse makes individuals more susceptible to pathogens such as HIV. The team wanted to investigate how the drug might reduce users' resistance to flu viruses.

They took cultures of human lung epithelial cells, exposed them to different concentrations of meth and then infected them with an H1N1 strain of human influenza A. By 30 to 48 hours after infection, the meth-treated cells had a much lower concentration of the virus than the control group, the researchers reported. What's more, this reduction occurred in a dose-dependent manner, meaning the more meth, the less the virus reproduced.

"We report the first evidence that meth significantly reduces, rather than increases, virus propagation and the susceptibility to influenza infection in the human lung epithelial cell line," wrote the researchers, led by Yun-Hsiang Chen.