Can catkins spread novel coronavirus?

Each year from April to early May is catkin season in northern China. People worry that these fluffy balls released from willow and poplar trees can spread novel coronavirus. But in fact, there isn't any evidence that viruses are contained in the catkins or pollen.

The novel coronavirus is mainly transmitted by respiratory droplets, with particles that are relatively large in size. An infection is only caused by inhaling them in large amounts at a close distance. Aerosols, formed by dehydrated droplets that contain proteins and viruses, can float and spread in the air. But it is hard for the virus to survive without the proper temperature and humidity. It won't stay in the air for long. Even if the virus stayed on a catkin, its concentration level would be too low to cause infections.

On the other hand, people still need to protect themselves from catkins as these pollen grains can cause allergies. For people with a sensitivity to pollen, inhaling catkins can cause nasal itching, sneezing, an itchy throat, headaches and allergic asthma - which in severe cases may lead to death by anaphylaxis.

To fight pollen allergies, wearing a maskis recommended to prevent inhaling catkins. Other effective measures include immediate washing of the hands, nose and face after coming back in from outside, prompt removal of catkins which are indoors or attached to clothes, a bland diet, drinking plenty of water and increasing indoor humidity. When going outdoors, try to choose a time when there are fewer flying catkins and avoid wearing a coat with a fabric that collects the catkins.