The team hope that the masks could be rolled out for public use, allowing a quick and easy way to test when the wearer has been exposed to the virus or is carrying the virus.

The project was led by Yasuhiro Tsukamoto, who told media that he had always wanted to carry out research on dinosaurs and modern birds, determining that ostriches were the best middle ground, having fingers and nails on the inside of their feathers, making them “very primitive and near dinosaurs”.

He keeps a flock of around 500 captive ostriches roaming in the mountain valleys; each female produces 50 to 100 eggs per year. Tsukamoto noticed in the early 1990s that his captive ostriches were oddly disease-free compared with other captive birds. He and other scientists identified this as being due to their eggs. In the later stages of pregnancy, mothers boost their offspring’s defences by passing on antibodies: mammals via placenta and milk, and birds through yolk.

Ostriches are capable...