From: Related terms: Download as PDF Set alert About this page D. Reid, D. Goldberg, in , 2012 Herd immunity Herd immunity is an important element in the balance between the host population and the micro-organism, and represents the degree to which the community is susceptible or not to an infectious disease as a result of members of the population having acquired active immunity from either previous infection or prophylactic immunization (see p. 731 ).
Herd immunity can be measured: 1 Indirectly from the age distribution and incidence pattern of the disease if it is clinically distinct and reasonably common.
This is an insensitive and inadequate method for infections that manifest subclinically.
2 Directly from assessments of immunity in defined population groups by antibody surveys (sero-epidemiology) or skin tests; these may show ‘immunity gaps’ and provide an early warning of susceptibility in the population.
Although it may be difficult to interpret the data in absolute terms of immunity and susceptibility, the observations can be standardized to reveal trends and differences between various defined population groups in place and time.
The decision whether to introduce herd immunity artificially by immunization against a particular disease will depend on several epidemiological principles.
• The disease must carry a substantial risk.
The effectiveness and safety of immunization programmes are monitored by observing the expected and actual effects of such programmes on disease transmission patterns in the community by appropriate epidemiological techniques.
URL: https://www.sciencedirect.com/science/article/pii/B9780702040894000822 Paolo Giorgi Rossi, Francesca Carozzi, in , 2019 Vaccination of boys Herd immunity is the main driver for the proposal of universal vaccination, that is, including boys and girls.
With growing evidence of the involvement of HPV in a relevant proportion of head and neck cancers, in particular oropharynx ( Plummer et al., 2016 ), it has become clear that the burden of vaccine-preventable disease in males is not negligible ( de Martel et al., 2017 ).
The vaccine has proven to be effective also on precancerous lesions of genital mucosae in males ( Palefsky et al., 2011 ).
Nevertheless, most models still predict that the largest benefit of vaccinating boys is the indirect effect on cervical cancer in women due to the reduction of circulating virus and to establishing of herd immunity faster ( Brisson et al., 2011 ).
The opportunity and cost effectiveness of vaccinating boys is still under debate, with the extreme heterogeneity of policies adopted in industrialized countries reflecting this uncertainty.
Given the very high incidence of HPV-related cancers in males having sex with males, there is consensus that vaccinating this group is opportune ( Markowitz et al., 2014 ; Kirby, 2015 ; Sauvageau and Dufour-Turbis, 2016 ), even though implementing effective strategies to target high-risk populations without indirectly fostering discrimination or stigmatization is challenging.
URL: https://www.sciencedirect.com/science/article/pii/B9780128012383651383 Catherine J. Luke, ... Kanta Subbarao, in , 2013 Herd immunity and indirect protection from LAIV Herd immunity is defined as the proportion of persons with immunity in a given population, 180 and the indirect protection afforded by this immunity to the unimmunized segment of the population is defined as the herd effect .
Herd immunity has been demonstrated for infectious diseases of viral and bacterial etiology, and it is widely accepted that this phenomenon occurs with influenza.
190 Excess mortality rates in Japan increased with discontinuation of the vaccination program for schoolchildren.
From a practical standpoint, LAIV could be an extremely effective method to achieve herd immunity if high vaccination rates with an efficacious vaccine are achieved in schoolchildren and influenza transmission to other segments of the community is interrupted.
Large numbers of children could be vaccinated in a short period of time, and intranasal administration is preferred over injection of inactivated vaccine.
The data from these studies support the widespread vaccination of schoolchildren as a means of reducing morbidity and mortality in other high-risk members of communities.
URL: https://www.sciencedirect.com/science/article/pii/B9781455700905000276 In , 2012 Summary • Herd immunity forms the theoretical basis for mass vaccination programs.
• In the twentieth century, mass vaccination programs were highly successful in eradicating childhood diseases such as diphtheria, pertussis, and tetanus.
• Viral antigens often change as a consequence of antigenic drift, antigenic shift, or genetic reassortment.
URL: https://www.sciencedirect.com/science/article/pii/B9780323069472100252 JOHN P. FOX, LILA R. ELVEBACK, in , 1975 In 1971, we discussed herd immunity and its relevance to immunization practices ( 1 ), using applications of the Reed-Frost epidemic model ( 2 ), and of a stochastic simulation model for a community of families ( 3 ) to illustrate the basic concepts.
This presentation draws heavily on our previous discussion * but also will consider how these concepts of herd immunity relate to some important current immunization problems.
The case was in a 3-child family and a 5-child play group and did not attend nursery school although his 2 siblings were among the 40 susceptibles who did attend.
URL: https://www.sciencedirect.com/science/article/pii/B9780125220507500204 Paul E.M. Fine, ... W. John Edmunds, in , 2018 Case Reproduction Numbers We can approach this herd immunity concept from an alternative, and equally informative, perspective.
If an infection is to persist, each infected individual must, on average, transmit the agent to at least one other individual.
5] R n = R 0 × S By this expression, if the proportion susceptible ( S ) were equal to the reciprocal of the basic reproduction number of the infection (1 / R 0 ), the average number of transmissions per case ( R n ) should be 1, and thus incidence should remain constant over time.
77.5B illustrates this, and it once again leads us directly to the herd immunity threshold ( H ).
Because the proportion immune is just the complement of the proportion susceptible ( H = 1 − S ), we have [Eq.
77.6 shows the relationship graphically, which shows the implications for persistence or decline of an infection depending on its basic reproduction number and the proportion of immune persons in the population.
1,13,16 URL: https://www.sciencedirect.com/science/article/pii/B9780323357616000778 Emmanuel Vidor, Stanley A. Plotkin, in , 2013 Herd immunity The best evidence for a herd immunity effect of IPV is the experience in the United States where IPV was introduced into routine use in 1955 and was replaced by OPV in 1962.
A sharp drop in the numbers of cases of paralytic and nonparalytic polio was evident during the years 1955 to 1962 ( Figure 27-5 ).
214 More specific regional data were published that suggested a greater than expected reduction in polio cases.
215 The second example of herd immunity comes from the Netherlands where vaccination is refused by a religious community that is well dispersed throughout the country, although IPV is routinely administered to the rest of the population.
Two outbreaks of polio have occurred in this religious group, one caused by type 1 virus in 1978 (110 cases) and the second by type 3 virus from 1992 to 1993 (71 cases).
Proof of recent type 3 infection was found in 59.5% of the unvaccinated children and in 22.2% of the vaccinated children.
The evidence for herd immunity comes from countries where oral-to-oral transmission was probably the dominant mode of interhuman poliovirus transmission.
It is less clear if IPV is able to induce herd immunity in countries where the fecal-to-oral route is thought to be the primary role in transmission.
URL: https://www.sciencedirect.com/science/article/pii/B9781455700905000343 RICHARD C. ROSATTE, ... DAVID H. JOHNSTON, in , 2007 10.2 Bait density Control ultimately depends on establishing herd immunity through animals taking baits and sero-converting.
Hence, bait density must correlate with animal density in some positive fashion ( Rosatte and Lawson, 2001 ).
(unpublished); f Matouch and Vitasek (2005) ; g Bigler and Lein (2001) ; h Nohrenberg, USDA(unpublished).
URL: https://www.sciencedirect.com/science/article/pii/B9780123693662500208 David S. Stephens, Michael A. Apicella, in , 2015 Herd Immunity and Introduction Strategies Protection against the bacterial meningitis pathogens through herd immunity is a remarkable, powerful, and unanticipated effect of bacterial polysaccharide-protein conjugate vaccines.
35 Herd immunity can account for approximately one half of their effectiveness at preventing disease and has significantly enhanced their cost-effectiveness.
It is an important strategy for vaccine introduction, implementation, and evaluation.
As noted, in 1999 to 2000 the meningococcal serogroup C conjugate vaccines were introduced in the United Kingdom as a broad catch-up campaign for those younger than 19 years of age, reduced nasopharyngeal carriage of serogroup C in adolescents more than 75%, and created herd immunity that has persisted for more than a decade.
413,417 The explanation for this remarkable herd immunity effect is the low R 0 (basic reproduction number, or the average number of secondary infectious cases that are produced by a single index case in completely susceptible population), estimated at 1.3, for meningococcal disease providing herd immunity with 17% to 26% vaccine coverage of the population.
35 ,434 In contrast, measles, mumps, pertussis, polio, and rubella have an R 0 greater than 5 and require much higher thresholds (i.e., >80% for herd immunity).
427 The immunologic basis of mucosal (herd) immunity with conjugate vaccines remains unclear.
Generation of capsule-specific mucosal immunoglobulins, transudation of high-avidity serum IgG to mucosal surfaces, and Th17-induced immunity via macrophage clearance have been proposed.
35 Cost-effectiveness, measured as a quality-adjusted life-year (QALY) score, is increasingly becoming an important consideration of vaccine recommendations in public health.