The ways in which human swine flu can spread include:

- A person infected with human swine flu is contagious as long as they are showing symptoms and for up to three days from the start of antiviral treatment.

- Young children may be infectious for longer.

- One infected person can transmit the virus to hundreds of people.

- A single droplet of 0.5 to 5µm in diameter or a single virus is enough to infect a person.

- A single sneeze releases over 40,000 droplets. The droplets can either remain as aerosol or settle on objects.

- A person caring for someone sick with human swine flu can become infected from inhaling infected sneeze or cough droplets. This is known as direct contact.

- The human swine flu virus can live for about two hours outside of the body. Infection can occur when a person touches a contaminated object (such as a dirty tissue) and then touches his or her own nose, eyes or mouth. This is known as indirect contact.

- The avian influenza virus can survive indefinitely when frozen.

- The virus can survive for one to two days on surfaces such as plastic or metal.

- And for about fifteen minutes on dry paper tissues but only five minutes on skin.

- In some cases, human swine flu is asymptomatic, which means the infected person feels fine and has no symptoms. However, they can still infect other people.

- Pig farmers can be infected directly from infected pigs i.e, for example, by handling sick pigs and not washing their hands.

- The majority of infections to date occurred as a result of the swine virus H3N2v being transmitted directly from pigs to humans, since most of the reported infected people were associated with pig farms or state fairs with pigs as predominant competition entries.