HERD IMMUNITY,HERD EFFECT,COMMUNITY IMMUNITY,POPULATION,IMMUNITY,SOCIAL,PROTECTION,INFECTIOUS,DISEASE,PERCENTAGE,IMMUNE,INFECTION,MEASURE,INDIVIDUALS,LARGE NUMBER,CHAINS,STOPS,SPREAD OF DISEASE,GREATER,PROPORTION,COMMUNITY,SMALLER,PROBABILITY,CONTACT,NATURAL,ARTIFICIAL,MEANS,CANNOT,MEDICAL,REASONS,GROUP,METHOD,ONCE,CERTAIN,THRESHOLD,REACHED,ELIMINATION,WORLDWIDE,PERMANENT,REDUCTION,NUMBER,INFECTIONS,ZERO,ERADICATION OF SMALLPOX,REGIONAL,DISEASES,APPLY,CONTAGIOUS,MEANING,FROM ONE,TETANUS,EXAMPLE,TERM,NATURALLY OCCURRING,PHENOMENON,CHILDREN,MEASLES,SUSCEPTIBLE,MASS VACCINATION,INDUCE,COMMON,PROVED,SPREAD,OPPOSITION TO VACCINATION,CHALLENGE,PERSIST,IN OR,RETURN,COMMUNITIES,INADEQUATE,RATES,DEPEND,DEVELOP,VACCINATED,NEWBORN INFANTS,TOO YOUNG,SAFETY,PASSIVE IMMUNITY,RENDERS,THE VACCINE,IMMUNODEFICIENCY,HIV AIDS,LYMPHOMA,LEUKEMIA,BONE MARROW CANCER,SPLEEN,CHEMOTHERAPY,RADIOTHERAPY,PREVIOUSLY,IMPERFECT,IMMUNE SYSTEMS,ADEQUATE,RESPONSE,CONFER,LONG TERM,LACK,VACCINE,CONTRAINDICATIONS,POPULATIONS,PREVENT,BECOMING,RISK,COMPLICATIONS,MEDICAL STATUS,GENERALLY,RELY,HIGH,CREATE,AGE GROUPS,ADULTS,PERTUSSIS,INFANTS,GREATEST,THE DISEASE,CLOSE,FAMILY MEMBERS,ACCOUNT,YOUNG,MANNER,PNEUMOCOCCUS,PNEUMOCOCCAL DISEASE,YOUNGER,SIBLINGS,CONVERSELY,ROTAVIRUS,THE EFFECT,OLDER,DO NOT,NORMALLY,INFLUENZA,FLU,ELDERLY,INFLUENZA VACCINE,EFFECTIVENESS,DEMOGRAPHIC,THE IMMUNE SYSTEM,SCHOOL AGE,SEASONAL FLU,EFFECTIVE,DEGREE,SEXUALLY TRANSMITTED INFECTION,SEX,INDUCES,SEXES,DECLINES,SEXUAL DISEASE,UPTAKE,THE TARGET,FEMALE,HOMOSEXUAL,MALES,THE OTHER,NEED TO,IMMUNIZED,THAT THAT,PROTECTED,HIGH RISK,BEHAVIORS,EVEN THOUGH,MODERATE,THE MAJORITY,ENGAGE,NECESSARY,IMMUNIZE,PERSONS,ORDER,ITSELF,ACTS,EVOLUTIONARY PRESSURE,VIRUSES,VIRAL EVOLUTION,PRODUCTION,NOVEL,STRAINS,CASE,ESCAPE,MUTANTS,ABLE,MOLECULAR,LEVEL,ANTIGENIC DRIFT,MUTATION,VIRAL,GENOME,VIRUSS,SURFACE,ANTIGEN,PROTEIN,THE VIRUS,CAPSID,CHANGE,EPITOPE,REASSORTMENT,ANTIGENIC SHIFT,CIRCULATION,PRODUCE,SEROTYPE,MEMORY T CELL,LONGER,RECOGNIZE,CEASES,RELEVANT,DOMINANT,STRAIN,NOROVIRUS,EPIDEMICS,CAUSING,WAVES,EVOLUTION,NEUTRALIZING ANTIBODIES,UNIVERSAL,BEYOND,DEVELOPMENT,SHIFTING,PREVALENCE,REPLACE,INITIAL,STREPTOCOCCUS PNEUMONIAE,REDUCED,CARRIAGE,ANTIBIOTIC RESISTANT,OFFSET,INCREASE,DISEASE INCIDENCE,LESS,INVASIVE,PNEUMOCOCCAL VACCINE,EMERGING,EMERGENCE,THE POSSIBILITY,FUTURE,REMAINS,STRATEGIES,DEAL WITH THIS,EXPANSION,COVERAGE,DEVELOPMENT OF,CELLS,ANTIGENS,PROTEINS,PRESENT,MULTIPLE,SUFFICIENT,PERIOD,NO MORE,ENDEMIC,CASES,PERMANENTLY,THUS,END RESULT,PUBLIC,HEALTH,INITIATIVES,CONTROL,BENEFITS,ENDING,MORBIDITY AND MORTALITY,CAUSED,FINANCIAL,SAVINGS,HEALTH CARE PROVIDERS,GOVERNMENTS,ENABLING,RESOURCES,USED TO,ELSEWHERE,DATE,RINDERPEST,SMALLPOX ERADICATION,UNDERWAY,POLIOMYELITIS,CIVIL UNREST,DISTRUST,MODERN MEDICINE,VARIETY,OBSTACLE,ENOUGH,PEOPLE,THE FREE RIDER PROBLEM,VACCINATE,FREE RIDE,THE HERD,FREE RIDERS,OUTBREAKS,GROUPTHINK,SOCIAL NORMS,PEER PRESSURE,RELIGIOUS BELIEFS,MISTRUST,OFFICIALS,RISKS,GREATER THAN,HIGH ENOUGH,PERSON,ALREADY,LARGE NUMBERS,BARRIER,SLOWING,TRANSMISSION OF DISEASE,ACQUIRED,CRITICAL,CEASING,CALCULATED,TAKING,BASIC REPRODUCTION NUMBER,AVERAGE,HOMOGENEOUS,MIXED,SUSCEPTIBLE INDIVIDUAL,MULTIPLYING,THE EQUATION,THE LEFT,WRITTEN,STOP,FUNCTIONS,VALUES,HITS,HIGHER,DEMAND,THEORETICALLY,NEEDS,CALCULATIONS,ENTIRE,IN REALITY,REPRODUCTIVE NUMBER,TIME T,FRACTION,SUSTAINED,BELOW,IN EXCESS,REDUCE,FASTER,RATE,SMALLER THAN,ABOVE,NEITHER,STEADY STATE,DECREASING,INFECTING,COMES,SOCIAL NETWORKS,LIMITED,TRANSMISSION,GEOGRAPHICALLY,PHYSICALLY,SHAPE,SIZE,NETWORK,ALTER,MORE OR LESS,DEPENDS,INTERACT,EACH OTHER,INTERACTIONS,CONNECTED,TRANSMIT,EXISTING,PRIMARY,BOOST,OBSERVATION,MILKMAIDS,EXPOSED,COWPOX,SMALLPOX,THE PRACTICE,VIRUS,DEVELOPED,SAFER,CAUSE,PROTECT,ADVERSE EFFECTS,DISTINGUISH,FORMING,ACTIVE,SIMILAR,MANUFACTURERS,FAILURE,POLICY,MAKERS,ENCOURAGE,INTRODUCTION,SHARP,DEATHS,CALCULATING,MUST,EQUATION,LESS THAN,IMPOSSIBLE,ACELLULAR,BOOSTER,SUSTAIN,CEASED,RELATION,THE PRODUCT,CETERIS PARIBUS,DECLINE,SHARPER,CONTRAINDICATION,VITAL,ALWAYS,FOR SOME,HIS OR HER,ANTIBODIES,NATURALLY,MATERNAL ANTIBODIES,IMMUNOGLOBULIN G,PLACENTA,COLOSTRUM,FETUSES,NEWBORNS,ARTIFICIALLY,SERUM,PLASMA,THE COURSE,WEEKS,MONTHS,CONTRIBUTION,PREGNANT WOMEN,TRANSFER,THE CHILD,THE SAME WAY,EXPERIENCE,ANTIBODY,SEVERITY,SYMPTOMS,CONDUCTING,POSITIVE EXTERNALITY,BENEFIT,THEREFORE,HERD,INCLUSION,RESULTS,COST EFFECTIVENESS,RATIOS,STUDY,DESIGNS,DONE,ESTIMATE,RECORDING,HOUSEHOLDS,MEMBER,GEOGRAPHIC AREA,OBSERVING,BEFORE AND AFTER,VACCINATION PROGRAM,DECREASE,THAT WHICH,PREDICTED,DIRECT,ALONE,PUBLISHED RESEARCH,EPIDEMIOLOGY OF MEASLES,BALTIMORE,NOTICE,SPITE,MEASLES VACCINE,THE MASS,DISCUSSIONS,DISEASE ERADICATION,SUBSEQUENTLY,THEOREM,CAMPAIGN,RING VACCINATION,INTEGRAL,RING,INFECTED,ADOPTION,CHALLENGES,ARISEN,MODELLING,EXIST,EQUATIONS,RECENT,DECADES,MICROORGANISM,ACTING,ONGOING,VACCINE CONTROVERSIES,PREMUNITY,WRITTEN BY,SHANE,KILLIAN,ROBERT WEBB,