Question

What virus causes the flu? Why doesn't the body produce permanent immunity against that virus? How does the vaccine against the flu work?

Answer 1

Part A

Flu is different from a cold.

While more than 100 different viruses can cause a cold, only influenza virus types A, B, and C cause the flu.

Type A and B viruses cause the large seasonal outbreaks.

Type C usually causes milder respiratory symptoms.

While the flu vaccinecan help protect you from types A and B, there is no immunization for type C virus.

Type A flu viruses are also found in many different animals, including ducks, chickens, pigs, whales, horses, and seals. Type B viruses only affect people.

Part B

Anyone who has a cold develops antibodies against the wrong part of the virus, so their immune response fails to protect them.

The immune response attacks the inside of the virus cell and not the envelope, which is what the virus uses to become established in the patient’s mucosal tissue.

This could be the reason why humans cannot become immune to colds in the same way as they do with other infectious diseases, such as measles.

When someone develops another cold, the antibodies once again attack the wrong part of the virus.

Part C

Vaccines work by stimulating our own body’s immune system to produce substances (antibodies) in the body to fight disease without us actually becoming infected with the disease.

Once the body has produced these antibodies, it remembers how to make them and can quickly deal with that virus in the future and stop it at an early stage – this is what is called immunity.

Flu vaccine contains viruses that are inactivated so that they don’t cause illness, but will still trigger your immune system to produce the right antibodies, giving you immunity against those viruses.

There are also small quantities of preservatives in the vaccine, and sometimes an ‘adjuvant’ that boosts your immune system to respond to the viruses.