Influenza A vs Influenza B: What's the difference?

The winter season is always accompanied by a series of respiratory diseases and flu is one of them. Caused by influenza viruses, flu can be diagnosed all year-round, but the cases increase drastically during the fall and winter. One of the reasons is because the virus can live longer indoors in winter due to less humid air.

Influenza or the flu is a highly contagious respiratory virus that can spread from one person to the other through respiratory droplets suspended in the air while sneezing or coughing. There are four types of influenza virus. Of all, influenza A is the most common, followed by influenza B. Both are highly contagious and can lead to severe symptoms like cough, headaches, muscle and joint pain, in severe cases, it can also worsen some chronic medical conditions, such as asthma, heart disease, and diabetes.

Influenza A viruses are the most powerful and the only type that can cause a pandemic. That's mainly because it can affect humans as well as animals. Wild birds commonly act as the hosts of the virus. Even bird flu and swine flu pandemics both are caused by a type of influenza A virus. It can spread when an infected person sneezes or coughs. Apart from that, people can also pick up the virus from the surfaces that an infected person has touched.

Read more: Flu cases on the rise: How long are you contagious when you have the flu?

Unlike the influenza A virus, influenza B viruses only cause a seasonal epidemic. Animals aren’t usually susceptible to the influenza B virus. Moreover, the B viruses mutate more slowly than influenza A viruses. It is transmitted after coming in contact with aerosol particles suspended in the air by an infected individual.

Out of the two, influenza A viruses are more common and account for about 75 per cent of the total confirmed cases of flu every year. Influenza B viruses are reported in less than 25 per cent of confirmed cases. Besides, the cases of flu caused by the influenza A virus are rife at the beginning of the flu season, while influenza B infections are reported more in the end.

Read more: Flu and diabetes risk: What to do and how to manage flu symptoms when you get sick, if you have diabetes

Both influenza A and B are highly contagious. The flu viruses suspended in the air by an infected person can infect others from up to 6 feet away, leading to severe infection. The tiny aerosol droplets can enter the other person's nose or mouth and cause severe symptoms. After coming in contact with the flu causing virus, the person starts developing symptoms in 2 days. The flu viruses are the most contagious in the first 3–4 days after falling ill.

For those who have a strong immune system, influenza does not lead to any severe symptoms. The condition is certainly unpleasant, but manageable. The risk of severity is higher for immunocompromised people, older adults, pregnant women and infants. It is common for both influenza A and B viruses.

Taking a flu shot before the beginning of the flu season is one of the best ways to protect yourself from influenza viruses. Apart from that, cover your nose and mouth when coughing and sneezing, maintain distance from those who show symptoms of flu and wash your hands before touching your face and nose. If you witness any symptoms of the flu seek medical help, rather than taking over-the-counter drugs.