Original: As of 2009, the known SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H3N1, H3N2, and H2N3.
Simplified: Types of flu strain include H1N1, H1N2, H3N1, H3N2, and H2N3. are known to cause swine influenza.