There are a number of flu shots available, and it is important to get professional medical advice from your doctor on the right flu shot that will work best for you. There are trivalent flu vaccines that protect against three strains of the virus: influenza A (H1N1), influenza A (H3N2), and influenza B virus; quadrivalent flu vaccines are different in that they can help protect you from different strains of the flu virus (two influenza A viruses and two influenza B viruses). There is the regular standard-dose quadrivalent shot for younger children, and then the high-dose quadrivalent shot for people ages 65 and older. The jet injection quadrivalent shot is commonly used on people ages 6 months or older or for people ages 18 to 64. The recombinant quadrivalent shot is for people 18 years old a up who have a severe egg allergy and live attenuated intranasal spray made from eggs is for those persons between the ages of 2 and 49 years of age who are not pregnant.