herd immunity


Summary: The non-susceptibility to infection of a large group of individuals in a population. A variety of factors can be responsible for herd immunity and this gives rise to the different definitions used in the literature. Most commonly, herd immunity refers to the case when, if most of the population is immune, infection of a single individual will not cause an epidemic. Also, in such immunized populations, susceptible individuals are not likely to become infected. Herd immunity can also refer to the case when unprotected individuals fail to contract a disease because the infecting organism has been banished from the population.

Top Publications

  1. Adewumi M, Donbraye E, Odaibo G, Bakarey A, Opaleye O, Olaleye D. Neutralizing antibodies against poliovirus serotypes among children in southwest Nigeria. J Trop Pediatr. 2006;52:92-5 pubmed
    ..The populations had 59.6 per cent herd immunity for the three poliovirus serotypes...
  2. May T, Silverman R. 'Clustering of exemptions' as a collective action threat to herd immunity. Vaccine. 2003;21:1048-51 pubmed
    ..Given the growing number of exemptions and the increasing visibility of the anti-vaccine movement, policy makers must be vigilant for dangerous clustering in order to avoid loss of herd immunity.
  3. Lloyd A, Patel N, Scott D, Runge C, Claes C, Rose M. Cost-effectiveness of heptavalent conjugate pneumococcal vaccine (Prevenar) in Germany: considering a high-risk population and herd immunity effects. Eur J Health Econ. 2008;9:7-15 pubmed
    ..to all children may lead to a decline in pneumococcal disease in unvaccinated adults, a phenomenon known as herd immunity. This analysis evaluated the cost and economic consequences in Germany of vaccinating (1) children at high ..
  4. Ali M, Emch M, von Seidlein L, Yunus M, Sack D, Rao M, et al. Herd immunity conferred by killed oral cholera vaccines in Bangladesh: a reanalysis. Lancet. 2005;366:44-9 pubmed
    ..Use of these vaccines could have a major effect on the burden of cholera in endemic settings. ..
  5. Paul Y. Herd immunity and herd protection. Vaccine. 2004;22:301-2 pubmed
  6. Trotter C, Gay N, Edmunds W. Dynamic models of meningococcal carriage, disease, and the impact of serogroup C conjugate vaccination. Am J Epidemiol. 2005;162:89-100 pubmed
    ..in England and Wales to develop and apply a mathematical model to investigate the direct and indirect (herd immunity) effects of a conjugate vaccine program...
  7. Hubben G, Bos J, Glynn D, van der Ende A, van Alphen L, Postma M. Enhanced decision support for policy makers using a web interface to health-economic models--illustrated with a cost-effectiveness analysis of nation-wide infant vaccination with the 7-valent pneumococcal conjugate vaccine in the Netherlands. Vaccine. 2007;25:3669-78 pubmed
  8. Piedra P, Gaglani M, Kozinetz C, Herschler G, Riggs M, Griffith M, et al. Herd immunity in adults against influenza-related illnesses with use of the trivalent-live attenuated influenza vaccine (CAIV-T) in children. Vaccine. 2005;23:1540-8 pubmed
    ..Vaccination of approximately 20-25% of children, 1.5-18 years of age in the intervention communities resulted in an indirect protection of 8-18% against MAARI in adults > or =35 years of age. ..
  9. Emch M, Ali M, Park J, Yunus M, Sack D, Clemens J. Relationship between neighbourhood-level killed oral cholera vaccine coverage and protective efficacy: evidence for herd immunity. Int J Epidemiol. 2006;35:1044-50 pubmed
    ..was inversely related to placebo incidence during the first year of surveillance, which was attributed to herd immunity. In this study we measure the relationship between neighbourhood-level oral cholera vaccine coverage and ..

More Information


  1. Ferrari M, Bansal S, Meyers L, Bjørnstad O. Network frailty and the geometry of herd immunity. Proc Biol Sci. 2006;273:2743-8 pubmed
    ..The result is that immunization due to prior epidemics can provide greater community protection than random vaccination on networks with heterogeneous contact patterns, while the reverse is true for highly structured populations. ..
  2. Garnett G. Role of herd immunity in determining the effect of vaccines against sexually transmitted disease. J Infect Dis. 2005;191 Suppl 1:S97-106 pubmed
    Vaccination programs provide both direct protection to those immunized and herd immunity, which is indirect protection of those who remain susceptible, owing to a reduced prevalence of infections...
  3. Claes C, Reinert R, von der Schulenburg J. Cost effectiveness analysis of heptavalent pneumococcal conjugate vaccine in Germany considering herd immunity effects. Eur J Health Econ. 2009;10:25-38 pubmed publisher
    ..have reported a reduction of pneumococcal diseases in both vaccinated and unvaccinated populations, suggesting herd immunity effects...
  4. Trotter C, Maiden M. Meningococcal vaccines and herd immunity: lessons learned from serogroup C conjugate vaccination programs. Expert Rev Vaccines. 2009;8:851-61 pubmed publisher
    ..Such herd immunity effects have been demonstrated following the introduction of meningococcal serogroup C conjugate (MCC) ..
  5. Bonds M, Rohani P. Herd immunity acquired indirectly from interactions between the ecology of infectious diseases, demography and economics. J R Soc Interface. 2010;7:541-7 pubmed publisher
    ..For example, because of indirect income effects, herd immunity may be acquired with lower vaccine coverage than previously thought...
  6. Robiolo B, La Torre J, Duffy S, Leon E, Seki C, Torres A, et al. Quantitative single serum-dilution liquid phase competitive blocking ELISA for the assessment of herd immunity and expected protection against foot-and-mouth disease virus in vaccinated cattle. J Virol Methods. 2010;166:21-7 pubmed publisher
    A single serum-dilution liquid phase ELISA (slpELISA) was standardized to be used for serological evaluation of herd immunity against foot-and-mouth disease...
  7. Kanai Y, Boonsathorn N, Chittaganpitch M, Bai G, Li Y, Kase T, et al. The impact of antigenic drift of influenza A virus on human herd immunity: Sero-epidemiological study of H1N1 in healthy Thai population in 2009. Vaccine. 2010;28:5437-44 pubmed publisher
    To examine the effect of the antigenic drift of H1N1 influenza viruses on herd immunity, neutralization antibodies from 744 sera from Thai healthy volunteers in 2008-2009, who had not been vaccinated for at least the last 5 years, were ..
  8. Haber M, Barskey A, Baughman W, Barker L, Whitney C, Shaw K, et al. Herd immunity and pneumococcal conjugate vaccine: a quantitative model. Vaccine. 2007;25:5390-8 pubmed
    ..In contrast, the herd immunity effects on vaccine-related serotype 6A incidence were inconsistent...
  9. Albrich W, Madhi S, Lafond K, Klugman K. Herd immunity after pneumococcal conjugate vaccination. Lancet. 2007;370:218-9; author reply 219-20 pubmed
  10. Cheung Y, Zaman S, Nsekpong E, Van Beneden C, Adegbola R, Greenwood B, et al. Nasopharyngeal carriage of Streptococcus pneumoniae in Gambian children who participated in a 9-valent pneumococcal conjugate vaccine trial and in their younger siblings. Pediatr Infect Dis J. 2009;28:990-5 pubmed publisher
    ..Vaccination had no indirect effect on carriage in younger siblings and there was limited impact on antibiotic resistance. ..
  11. Armstrong G, Billah K, Rein D, Hicks K, Wirth K, Bell B. The economics of routine childhood hepatitis A immunization in the United States: the impact of herd immunity. Pediatrics. 2007;119:e22-9 pubmed
    ..This analysis estimates the impact of herd immunity on the cost-effectiveness of routine hepatitis A immunization among US children...
  12. Wisløff T, Abrahamsen T, Bergsaker M, Løvoll Ø, Møller P, Pedersen M, et al. Cost effectiveness of adding 7-valent pneumococcal conjugate (PCV-7) vaccine to the Norwegian childhood vaccination program. Vaccine. 2006;24:5690-9 pubmed
    ..adding this pneumococcal vaccine to the Norwegian childhood vaccination programme, taking the possibility of herd immunity into account...
  13. Poehling K, Talbot T, Griffin M, Craig A, Whitney C, Zell E, et al. Invasive pneumococcal disease among infants before and after introduction of pneumococcal conjugate vaccine. JAMA. 2006;295:1668-74 pubmed
    ..With a significant decrease in rates of IPD among black infants, the previous racial difference has been eliminated. ..
  14. Kaplan E, Wein L. Smallpox eradication in West and Central Africa: surveillance-containment or herd immunity?. Epidemiology. 2003;14:90-2 pubmed
  15. McIntosh E, Conway P, Willingham J, Hollingsworth R, Lloyd A. Pneumococcal pneumonia in the UK--how herd immunity affects the cost-effectiveness of 7-valent pneumococcal conjugate vaccine (PCV). Vaccine. 2005;23:1739-45 pubmed
    ..b>Herd immunity effects on adult pneumococcal hospital-treated pneumonia, meningitis and septicaemia, but not on community-..
  16. Halloran M, Longini I, Nizam A, Yang Y. Containing bioterrorist smallpox. Science. 2002;298:1428-32 pubmed
    ..was more effective than targeted vaccination in preventing and containing epidemics if there was no prior herd immunity (that is, no prior immunologic protection within the population)...
  17. Humolli I, Dedushaj I, Zupanac T, Mucaj S. Epidemiological, serological and herd immunity of Crimean-Congo haemorrhagic fever in Kosovo. Med Arh. 2010;64:91-3 pubmed
    ..Goal of the research was to establish a pattern of the disease, its natural flow and herd immunity. For this purpose we used epidemiological methods, laboratory confirmation (ELISA, PCR) and t-test and chi2-..
  18. Campbell H, Andrews N, Borrow R, Trotter C, Miller E. Updated postlicensure surveillance of the meningococcal C conjugate vaccine in England and Wales: effectiveness, validation of serological correlates of protection, and modeling predictions of the duration of herd immunity. Clin Vaccine Immunol. 2010;17:840-7 pubmed publisher
    ..02 case per 100,000 population) in the 2008-2009 epidemiological year, mainly due to the indirect herd immunity effect of the vaccine in reducing carriage...
  19. Ramsay M, Andrews N, Trotter C, Kaczmarski E, Miller E. Herd immunity from meningococcal serogroup C conjugate vaccination in England: database analysis. BMJ. 2003;326:365-6 pubmed
  20. Trotter C, Andrews N, Kaczmarski E, Miller E, Ramsay M. Effectiveness of meningococcal serogroup C conjugate vaccine 4 years after introduction. Lancet. 2004;364:365-7 pubmed
    ..the incidence of serogroup C disease, as a result of high short-term vaccine effectiveness and substantial herd immunity. However, the long-term effectiveness of the vaccine remains unknown...
  21. Maiden M, Ibarz Pavón A, Urwin R, Gray S, Andrews N, Clarke S, et al. Impact of meningococcal serogroup C conjugate vaccines on carriage and herd immunity. J Infect Dis. 2008;197:737-43 pubmed publisher
    ..The impact of this intervention on asymptomatic carriage of meningococci was investigated to establish whether serogroup replacement or protection by herd immunity occurred.
  22. van Boven M, Bouma A, Fabri T, Katsma E, Hartog L, Koch G. Herd immunity to Newcastle disease virus in poultry by vaccination. Avian Pathol. 2008;37:1-5 pubmed publisher
    ..As a consequence, herd immunity can only be achieved if a high proportion of birds (>85%) have a high antibody titre (log(2) ..
  23. Melegaro A, Edmunds W. Cost-effectiveness analysis of pneumococcal conjugate vaccination in England and Wales. Vaccine. 2004;22:4203-14 pubmed
    ..The impact of indirect effects of the vaccine, such as herd immunity and serotype replacement, were investigated and their relative importance was assessed by performing ..
  24. Nishiura H, Dietz K, Eichner M. The earliest notes on the reproduction number in relation to herd immunity: Theophil Lotz and smallpox vaccination. J Theor Biol. 2006;241:964-7 pubmed
  25. Hyde T, Dayan G, Langidrik J, Nandy R, Edwards R, Briand K, et al. Measles outbreak in the Republic of the Marshall Islands, 2003. Int J Epidemiol. 2006;35:299-306 pubmed
    ..Islands' of measles susceptibility may develop in infants, adults, and any groups with low vaccine coverage. To prevent outbreaks, high population immunity must be sustained by maintaining and documenting high vaccine coverage. ..
  26. Klugman K, Madhi S. Pneumococcal vaccines and flu preparedness. Science. 2007;316:49-50 pubmed
  27. Snedecor S, Strutton D, Ciuryla V, Schwartz E, Botteman M. Transmission-dynamic model to capture the indirect effects of infant vaccination with Prevnar (7-valent pneumococcal conjugate vaccine (PCV7)) in older populations. Vaccine. 2009;27:4694-703 pubmed publisher
    ..The model predicts the observed incidence of IPD with good agreement and may be used to predict the impact of various vaccination strategies in the US or other populations yet to introduce PCV7. ..
  28. Bouma A, Claassen I, Natih K, Klinkenberg D, Donnelly C, Koch G, et al. Estimation of transmission parameters of H5N1 avian influenza virus in chickens. PLoS Pathog. 2009;5:e1000281 pubmed publisher
    ..Simulations based on the estimated parameters indicate that herd immunity may be obtained if at least 80% of chickens in a flock are vaccinated...
  29. Emch M, Ali M, Acosta C, Yunus M, Sack D, Clemens J. Efficacy calculation in randomized trials: global or local measures?. Health Place. 2007;13:238-48 pubmed
    ..Local efficacy measures can help public health practitioners make better decisions about when and where to vaccinate populations. The concepts offered in this study are pertinent for any health intervention trial, not just vaccines. ..
  30. Domenech J, Lubroth J, Sumption K. Immune protection in animals: the examples of rinderpest and foot-and-mouth disease. J Comp Pathol. 2010;142 Suppl 1:S120-4 pubmed publisher
    ..These differences may in part explain the respective advancement of international eradication campaigns: while global eradication of rinderpest is imminent, FMD viruses are still actively circulating in many parts of the world...
  31. Steinhoff M, Goldblatt D. Conjugate Hib vaccines. Lancet. 2003;361:360-1 pubmed
  32. Siegal G, Siegal N, Bonnie R. An account of collective actions in public health. Am J Public Health. 2009;99:1583-7 pubmed publisher
    ..where collective participation is a prerequisite for achieving an important public health goal such as herd immunity. In such circumstances, concerted action often falls short of the common good through lack of sufficient ..
  33. Tasslimi A, Wenger P, Pentakota S, Brimacombe M, Burday M, Sinha A. Invasive pneumococcal disease in an underimmunized, high HIV prevalence population. J Infect. 2008;56:99-102 pubmed publisher
    ..At-risk populations, with high HIV prevalence and relatively low infant PCV7 immunization rates, may still be benefiting from PCV7-related herd protection effects. ..
  34. Kayhty H, Auranen K, Nohynek H, Dagan R, Mäkelä H. Nasopharyngeal colonization: a target for pneumococcal vaccination. Expert Rev Vaccines. 2006;5:651-67 pubmed
    ..the protection afforded by the vaccine extends to the whole population, including those not vaccinated (herd immunity)...
  35. Wals P, Carbon M, Sévin E, Deceuninck G, Ouakki M. Reduced physician claims for otitis media after implementation of pneumococcal conjugate vaccine program in the province of Quebec, Canada. Pediatr Infect Dis J. 2009;28:e271-5 pubmed publisher
    ..2% by the end of the study period. PCV-7 implementation was associated with a significant reduction in the frequency of OM in the target population, and there was no indication of herd protection in older children. ..
  36. May T. Vaccines as community-focused therapy. Expert Rev Vaccines. 2003;2:341-3 pubmed
  37. Trotter C, Edmunds W, Ramsay M, Miller E. Modeling future changes to the meningococcal serogroup C conjugate (MCC) vaccine program in England and Wales. Hum Vaccin. 2006;2:68-73 pubmed
    ..program has successfully controlled serogroup C disease, due to high vaccine effectiveness and substantial herd immunity. However, children immunised at 2, 3 and 4 months of age receive only short-term direct protection and may be ..
  38. Silfverdal S, Berg S, Hemlin C, Jokinen I. The cost-burden of paediatric pneumococcal disease in Sweden and the potential cost-effectiveness of prevention using 7-valent pneumococcal vaccine. Vaccine. 2009;27:1601-8 pubmed publisher
    ..This model demonstrates that implementing a universal vaccine programme in Sweden with PCV7 would be cost-effective with an estimated net reduction of costs for the society. ..
  39. Glezen W. Herd protection against influenza. J Clin Virol. 2006;37:237-43 pubmed
    ..School-based clinics could provide a platform for rapid deployment of vaccine accessible to all segments of the population. This strategy could be critical for control of pandemic influenza. ..
  40. Ooi E, Goh K, Gubler D. Dengue prevention and 35 years of vector control in Singapore. Emerg Infect Dis. 2006;12:887-93 pubmed
    ..We identify potential causes of this resurgence. A combination of lowered herd immunity, virus transmission outside the home, an increase in the age of infection, and the adoption of a case-reactive ..
  41. Zielinski A, Stefanoff P. [Herd immunity and effectiveness of vaccination]. Przegl Epidemiol. 2004;58 Suppl 1:10-6 pubmed
    ..The definitions and ways of estimation of indicators of herd immunity as applied to the analysis of the effectiveness of vaccinations are presented.
  42. Tilson L, Usher C, Butler K, Fitzsimons J, O Hare F, Cotter S, et al. Economic evaluation of a universal childhood pneumococcal conjugate vaccination strategy in Ireland. Value Health. 2008;11:898-903 pubmed publisher
    ..In a separate submodel, the effect of herd immunity was investigated...
  43. Tennenbaum S. Simple criteria for finding (nearly) optimal vaccination strategies. J Theor Biol. 2008;250:673-83 pubmed
    ..vaccination resources away from the high-risk group to the high-activity group will result in improved herd immunity in both the high-risk group and the population as whole...
  44. Treanor J. Influenza--the goal of control. N Engl J Med. 2007;357:1439-41 pubmed
  45. Kahn J. What vaccination programs mean for research. Am J Bioeth. 2007;7:3-4 pubmed
  46. Kinlin L, Jamieson F, Brown E, Brown S, Rawte P, Dolman S, et al. Rapid identification of herd effects with the introduction of serogroup C meningococcal conjugate vaccine in Ontario, Canada, 2000-2006. Vaccine. 2009;27:1735-40 pubmed publisher
    ..These apparent dramatic effects of conjugate C vaccine (both direct and indirect) may be important in the implementation and evaluation of vaccine policy in other jurisdictions. ..
  47. Bekker A, Chou C, Bernstein H. Update on universal annual influenza immunization recommendations for children. Curr Opin Pediatr. 2009;21:122-6 pubmed publisher
    ..New research has examined the effect of 'herd immunity' associated with immunizing all school-aged children, the suboptimal antigenic match between the trivalent ..
  48. Wisløff T, Abrahamsen T, Bergsaker M, Løvoll Ø, Kristiansen I. [Vaccination--value for money?]. Tidsskr Nor Laegeforen. 2006;126:2670-3 pubmed
    ..main challenge lies in obtaining valid estimates of health effects and side effects and the consequences of herd immunity and serotype shift...
  49. Ortega Sanchez I, Meltzer M, Shepard C, Zell E, Messonnier M, Bilukha O, et al. Economics of an adolescent meningococcal conjugate vaccination catch-up campaign in the United States. Clin Infect Dis. 2008;46:1-13 pubmed publisher
    ..11-17 years, followed by routine annual immunization of each child aged 11 years, could generate immediate herd immunity benefits...
  50. Hollinger F, Bell B, Levy Bruhl D, Shouval D, Wiersma S, Van Damme P. Hepatitis A and B vaccination and public health. J Viral Hepat. 2007;14 Suppl 1:1-5 pubmed
    ..evidence indicates that such programmes can result in impressive reductions in the incidence of hepatitis A by herd immunity. Monitoring of these populations to determine durability of protection will be important to avoid shifting the ..
  51. Lipsitch M, O Neill K, Cordy D, Bugalter B, Trzcinski K, Thompson C, et al. Strain characteristics of Streptococcus pneumoniae carriage and invasive disease isolates during a cluster-randomized clinical trial of the 7-valent pneumococcal conjugate vaccine. J Infect Dis. 2007;196:1221-7 pubmed
    ..PCV7) has led to significant reductions in disease while changing pneumococcal population dynamics via herd immunity and serotype replacement...
  52. Weber C. Update on childhood immunizations. Urol Nurs. 2005;25:214-5 pubmed