Related by context. Frequent words. (Click for all words.) 45 Southern Hemisphere 43 southern hemisphere 43 flu strains 41 flu vaccine 40 northern hemisphere 40 flu viruses 39 FluMist 39 seasonal flu 39 pandemic strain 39 swine flu vaccine 38 influenza strains 37 H#N# strain 37 flu vaccines 37 pandemic H#N# 37 swine flu vaccines 37 flu 37 flu virus 37 vaccine 37 influenza virus 37 influenza viruses 36 vaccines 36 Northern Hemisphere 36 H#N# viruses 36 Flu Vaccine 36 H#N# vaccine 35 Aventis Pasteur 35 Seasonal flu 35 Relenza 35 influenza vaccines 35 influenza vaccine 35 Sanofi Pasteur 34 nasal spray vaccine 34 seasonal influenza vaccine 34 Flu 34 seasonal influenza 34 Vaccines 34 Gardasil 34 Fauci 33 Whooping cough 33 influenza 33 virus mutates 33 Flu vaccine 33 Prevnar 33 Vaccine 33 Tamiflu 32 Schuchat 32 H#N# vaccines 32 antiviral drugs 31 nasal spray 31 H#N# 31 H#N# swine flu 31 H#N# Vaccine 31 oseltamivir 31 whooping cough 31 swine flu virus 30 adjuvants 30 pertussis 30 La Nina 30 Fuzeon 30 pneumococcal disease 30 swine flu pandemic 30 tropics 29 nasal sprays 29 vaccinate 29 monkeypox 29 Smallpox 29 El Nino 29 Cervarix 29 Gerberding 29 antivirals 29 immunize 29 Immunization Practices 29 vitamin D. 29 avian flu virus 29 ELVs 29 Sinovac 29 H#N# pandemic 29 H#N# influenza virus 28 pandemic 28 anti viral 28 H#N# flu 28 sanofi pasteur 28 pandemic flu 28 HPV 28 cervical cancer vaccine 28 antiviral drug 27 chickenpox 27 generic drugs 27 tropical cyclones 27 human papilloma virus 27 sexually transmitted virus 27 doses 27 smallpox 27 flu outbreak 27 H#N# virus 27 La Niña 27 Cerezyme 27 swine flu 27 chicken pox 27 H#N# avian flu 27 northern latitudes