Physics covers a wide range of phenomena, from elementary particles (such as quarks, neutrinos, and electrons) to the largest superclusters of galaxies. Included in these phenomena are the most basic objects composing all other things. Therefore, physics is sometimes called the  fundamental science .
Two types of influenza vaccines are available: 1  TIV (flu shot (injection) of trivalent (three strains; usually A/H1N1, A/H3N2, and B) inactivated (killed) vaccine) or. 2  LAIV (nasal spray (mist) of live attenuated influenza vaccine.)
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.