Social & Preventive Medicine All the following are true regarding Type A influenza virus, EXCEPT: A There are only 14 subtypes of haemagglutinin B There are only 9 subtypes of neuraminidase antigen C Humans are generally infected by virus of subtype H1, H2 or H3 and N1 or N2. D It shows both antigenic shift and drift 💡 Explanation All the following are true regarding Type A influenza virus, EXCEPT: ✓ Correct Answer: A. There are only 14 subtypes of haemagglutinin