Question: How effective are flu jabs / sprays ?

Srinath Kasturirangan answered on 13 Mar 2019:

I previously worked for a company that developed Flu vaccines. If you got the nasal flu spray ever, there is a good chance it was made by Medimmune (located at Granta Park in Cambridge). The tricky thing about the flu is that it mutates – keeps making small changes to its genetic makeup – that makes it very difficult to predict and develop vaccines for. However, scientist can take a best guess on what the makeup of the flu virus is going to be this season based on changes it has undergone in the past years and they try to generate vaccines based on this best guess. Sometimes it is a combination of multiple vaccines – Medimmune makes a Quadrivalent flu vaccine which goes after 4 different “strains” or variants of the flu. So if in a particular season the flu vaccine is very effective – then the scientsts guessed right! If it is not effective at all then the flu virus outsmarted us this time around!!