But diapers aren't meant to safeguard against vapours or other elements in tear gas, so neither will a surgical mask. The N95 or X301 do not protect the wearer from pollution. Yu says the respirators block containments in particle form only, not gases like ozone and nitrogen dioxide.
Flu vaccine is an inactivated vaccine, meaning that it contains killed influenza virus. The killed influenza virus is injected into muscles or skin and stimulates the immune system to produce an immune response (antibodies) to the influenza virus.
The CDC explains it well: Quadrivalent Influenza Vaccine. The strains of influenza used in the annual vaccine are based on predominant strains noted during international surveillance: Selecting the Viruses in the Seasonal Influenza (Flu) Vaccine as well as availability of matched lab strains to use in making the vaccine.