Related by context. Frequent words. (Click for all words.) 68 influenza virus 66 flu virus 64 flu strains 63 flu viruses 62 pandemic 62 swine flu virus 62 influenza pandemic 61 influenza viruses 61 H#N# strain 60 flu pandemic 59 pandemic flu 58 pandemic influenza 58 influenza 56 H#N# virus 56 seasonal influenza 55 H#N# 55 bird flu virus 53 seasonal flu 53 virus 52 vaccine 52 H#N# pandemic 52 H#N# swine flu 51 avian flu 51 avian influenza 49 influenza vaccine 49 Influenza 49 flu vaccines 48 pathogen 48 bird flu 48 flu epidemic 48 viruses 48 bacterium 48 pandemics 48 bird flu pandemic 48 vCJD 48 antiviral drugs 48 flu 48 H#N# bird flu 47 H#N# flu 47 rotavirus 47 pertussis 47 pathogens 47 antivirals 47 vaccines 47 flu vaccine 46 swine flu vaccine 46 swine flu pandemic 46 mutate 46 H#N# influenza 46 swine flu 46 H#N# vaccine 46 microbe 45 Tamiflu 45 epidemics 45 anti viral 44 antibodies 44 chickenpox 44 smallpox 44 Ebola 44 antiviral drug 44 organism 43 vaccinated 43 pathogenic 43 WNV 43 mutation 43 bird flu outbreak 43 HBV 43 antiviral 43 HPV 43 mutations 43 bacteria 43 genetic variation 42 SARS virus 42 virulence 42 hepatitis C virus 42 measles 42 Fauci 42 outbreak 42 swine flu outbreak 42 Prevnar 42 antibiotic resistance 42 Bird flu 42 Gerberding 42 C. difficile 42 unvaccinated 41 antigens 41 mumps 41 Relenza 41 dengue 41 mutated 41 inoculation 41 prions 40 human immunodeficiency virus 40 whooping cough 40 resistant bacteria 40 bacterial meningitis 40 incubation period 40 malaria 40 genetic mutation 40 superbug 40 West Nile virus