Influenza a的意思

"Influenza A" refers to one of the types of influenza viruses that can cause influenza, or flu, in humans and other animals. Influenza viruses are classified into three main types: A, B, and C. Influenza A viruses are the most common cause of flu epidemics and pandemics.

Influenza A viruses are further subdivided into different subtypes based on the types of hemagglutinin (H) and neuraminidase (N) proteins on their surfaces. There are 18 different known H subtypes and 11 known N subtypes, which can combine in different ways to create different influenza A virus strains.

Some influenza A virus subtypes, such as H1N1, H2N2, and H3N2, can infect humans, while others primarily infect birds, pigs, horses, or other animals. When an influenza A virus that is primarily found in animals crosses over to humans, it can cause a flu pandemic if humans have little or no immunity to the new virus.

Influenza A viruses can cause a wide range of symptoms, from mild to severe, and can be particularly dangerous for young children, the elderly, and people with compromised immune systems. Vaccines and antiviral medications are available to prevent and treat influenza, but the effectiveness of these measures can vary depending on the specific influenza A virus strains that are circulating each year.