This Centers for Disease Control (CDC) scientist was using a pipette to transfer H7N9 virus into vials for sharing with partner laboratories for public health research purposes. Human infections with avian influenza (AI, or bird flu) are rare but do occur, most commonly after exposure to infected poultry (Bird-to-human spread). Limited person-to-person spread of bird flu is thought to have occurred rarely in the past, most notably with avian influenza A (H5N1). Based on this previous experience, some limited human-to-human spread of this H7N9 virus would not be surprising. Most important, however, is that this transmission not be sustained (ongoing).