Talk:Herd immunity/Archive 1

Herd immunity questions

 * community resistance
 * decreased probability of epidemic
 * how measure herd immunity?
 * Proportion immune in population
 * Herd immunity and chance of carrier contact
 * how much herd immunity enough?
 * How infectious is disease
 * What is incubation period
 * What is the size and social behavior of group? —Preceding unsigned comment added by 195.229.149.1 (talk • contribs) 22 February 2006


 * I edited a bit of information which wasnt entirely true and was plainly said: a bit dumb. I added my experiences and my knowledge of immunology to make this article look more scientific. I also read the claim of that vaccination stops the disease from spreading, which doesnt need any citation or source, because its plain logic that this is true. But epidemiologists dont do research on vaccinations, they use the data obtained from the research and try to place that information in a context of enviromental factors and groups which are most likely effected etc. etc.. The researches are the virologists. I also removed the not-verified tag, it looks good now.
 * Greets, Dutch med student. —Preceding unsigned comment added by 80.56.155.7 (talk • contribs) 23 September 2006

Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children.
New research relevant to questions of herd immunity:


 * Glanz JM et al. Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children. Pediatrics 2009 Jun; 123:1446.


 * "CONCLUSIONS: Children of parents who refuse pertussis immunizations are at high risk for pertussis infection relative to vaccinated children. Herd immunity does not seem to completely protect unvaccinated children from pertussis. These findings stress the need to further understand why parents refuse immunizations and to develop strategies for conveying the risks and benefits of immunizations to parents more effectively."

-- Brangifer (talk) 13:40, 7 July 2009 (UTC)
 * Done. - 2/0 (cont.) 07:28, 10 July 2009 (UTC)
 * I forgot to mention in that edit summary that I took out the example of tetanus as a vaccine-preventable disease for which herd immunity does not apply. It was a bit awkwardly worded and not strictly on-topic, but I can see the value of examples if anyone else wants to put it back. - 2/0 (cont.) 07:33, 10 July 2009 (UTC)

Social networks
I added a bit on how the standard herd immunity definition / calculation changes when you consider social structure, based on some recent literature. Perhaps this section could be expanded to give a more general treatment of how various characteristics of a population (size, behavior, social ties...) impact herd immunity. Tinntinnabulation (talk) 12:56, 9 August 2010 (UTC)


 * I think the last sentence about herd immunity in "social networks" being "more fragile" is going to throw people for a loop. In a lightly connected mesh the threshold should be easier to achieve in theory, and that is what the reader is preloaded with before reading that sentence, and it would hold to theory if we were immunizing e.g. meercats or other animals that avoid contact with other family groups.  The sentence should probably read something like "While social networks have a lower herd immunuty threshold, among humans the perception of this lower threshold adversely affects voluntary innoculation rates." (140.232.0.70 (talk) 20:06, 10 March 2014 (UTC))


 * I agree that the last sentence does not follow logically from the rest of the paragraph. The linked article uses "social network" in the sense that humans will imitate their peers, not in the mathematical sense as in the comparison between well-mixed populations and social networks. I have changed the sentence to "While social networks have a lower herd immunity threshold, in humans, the perception of this lower threshold can adversely affect voluntary innoculation rates, potentially making herd immunity more fragile." 128.135.100.105 (talk) 22:16, 13 October 2014 (UTC)

Need for a better citation than current [4] (Blaylock)
The statement "The reason for this is that naturally-acquired immunity lasts for a lifetime." is currently supported by [4], which is Blaylock, Russell. "The Deadly Impossibility Of Herd Immunity Through Vaccination". This article also merely makes that statement without citing any supportive data or study.

This might be a good reference to cite in another context, because it is an article that is critical of the use of herd immunity to justify vaccinations. I am not qualified to say if the article itself is well-supported. — Preceding unsigned comment added by 108.253.214.54 (talk) 15:21, 10 April 2013 (UTC)

Criticisms?
In a 2011 article published under authority of the British Society for Ecological Medicine, as part of its conference entitled "The Health Hazards of Disease Prevention," Dr. Lucija Tomljenovic disputes the soundness of the herd immunity principle. Tomljenovic notes that herd immunity rests "on the assumption that vaccines are effective in conferring immunity to the individual," but points to a study by Gustafson et al. which found an outbreak of measels had occured in a population where over 95% had been immunized. Tomljenovic asserts: "[I]f the measles vaccine was effective in providing herd-protection, then the <5% of children in this study who did not seroconvert would still have had protection from contracting measles."

The implication for Tomljenovic here seems to be that herd immunity is reliant on the premise that the immunity of the 95%+ will by extension protect the >5% who did not receive the immunization; but the Gustafson study clearly refutes this premise. I feel that it would be appropriate to include criticisms of the herd-immunity principle. This article currently reflects an unsubstantiated opinion that herd-immunity is unchallenged.ZTFulkerson (talk) 05:10, 18 June 2013 (UTC)


 * Such a section would be comprised exclusively of anti-vaxxers, whose opinions should be disregarded on Wikipedia, which serves to be an encyclopedic overview of medical consensus, not a public opinion venue.


 * Your article only seems to be sourced by anti-vaxxers, so their points of view of herd immunity should be ignored here. More so, Tomljenovic herself does not seem well educated on the subject (or she is but opts to mislead others for her own personal gain, whatever that may be), as she makes numerous falsehoods and half-truths about the HPV vaccines in a 2 minute video. Regarding the outbreak you mention, 74 of the 1806 students were seronegative for measles vaccination (4.1%) and 0.7% contracted the virus. 14 of the 74 (19%) with no seroconversion fell ill while 0% of those with seroconversion did (an additional 3 seronegatives turned seropositive from seemingly asymptomatic infections). These are very good statistics that support the concept of herd immunity, as the number of people who fell ill was substantially less than what would have happened had 70% or 50% been vaccinated. It is important to take note that, as the study infers, most vaccines (like those for measles) do not confer immunity in 100% of people (it's also important to note that this outbreak occurred in a school, where people come into close contact with a large number of other people every day, increasing the likelihood of others becoming infected). This means that some of those who are vaccinated may contract the disease, as seen in this outbreak. But this is just a reason to have higher percentages of the population vaccinated so that more will be immune and won't be likely to spread the disease. Thanks to a low vaccine failure rate and high vaccine uptake, the majority of people with no immunity were protected by those with immunity, which is what you would expect if herd immunity in a population has been achieved. ComfyKem (talk) 09:12, 18 June 2013 (UTC)


 * This is offensively disrespectful, and completely in opposition to the premise of science being about the observed data, that only constrains the acceptable interpretations to what fits the facts. First, there are dissensions, anti-vaxers, and non-vaxers among medical personnel. Second, there are other scientists than medical personnel who are quite capable of looking at the data and coming to informed opinions. "Scientists" who are unwilling to have the review of people from other disciplines, or even the general public review their work and challenge them on it, have degenerated to the level of snake oil salesmen. If the response to a challenge by such people can not be adequately met, then until it can, the hypothesis must be considered unsupported or at best incompletely supported. It is the responsibility of the person presenting the hypothesis to either explain it in terms that others can understand, or point them to the information that they can research to understand better. It is the responsibility of the person challenging to be willing to do their best to understand what is being explained, acknowledge when there is something that they just can't understand and/or don't have the time to gain the understanding, and give the hypothesizer the benefit of the doubt, allowing the hypothesis to continue until and unless they can challenge it from understanding. But if a garbage man understands the concepts and brings a challenge on the basis of the data, then the most renowned scientist must respond as if he is talking with a peer. Otherwise, science would be nothing more than the opinions of an oligarchy. I submit to you that it will be better for everyone if we can improve the level of respect involved. Leolore (talk) 07:05, 11 February 2015 (UTC)


 * The graphic demonstrates a misleading conceptual problem. In the second line, in fact all of the population should be yellow except the five, because they have all been exposed to the disease, and gained natural immunity. In general, this discussion of Herd Immunity correspondingly does not seem to include much about the immunity of people who have (naturally) gotten the disease, basically claiming that Herd Immunity can only come from vaccines. This is a serious logical flaw: if ONLY the vaccine leads to herd immunity, then the antibodies produced by exposure to the disease would be ineffective in preventing the disease, but this is the whole basis of the science behind a vaccine (thus serious logical flaw).
 * The graphic demonstrates a misleading conceptual problem. In the second line, in fact all of the population should be yellow except the five, because they have all been exposed to the disease, and gained natural immunity. Leolore (talk) 07:05, 11 February 2015 (UTC)


 * I see that there is concern about the Herd Immunity for Measles among other things. The yearly data between 1950 and 2011 from the CDC shows that cases of the measles were on a downward trend from at least 1956, years before the introduction of the vaccine, and the trend for measles cases after the vaccine had no statistically significant deviation from the trend. The vaccine seems to have ridden the trend, not caused it. I do not have numeric data from before this time, but have seen graphs that seem to greatly reinforce that the trend was downward far before introduction of the vaccine. Leolore (talk) 07:05, 11 February 2015 (UTC)


 * Placing the blame on parents who choose not to vaccinate appears to be politically motivated, not scientific. For example, the most likely reason for resurgence of disease in an population that has previously had Herd Immunity is a large turnover in the population - i.e. a spike in immigration, a similar reason might be a large spike in births (although some resistance can be passed down by this means). There could be other reasons. Given the previous paragraph, it is also not unreasonable to expect spikes in cases from time to time, such as the one that we saw around 1990, and the one previous to that around 1971. It would be far better to keep to the science: to simply state that there is a concern about the loss of Herd Immunity, and that those who believe that vaccinations brought about Herd Immunity in the first place also believe that increasing the percentage of the population vaccinated will help. This way, you acknowledge the concern without placing blame. You might also acknowledge the contrasting medical opinion that the proliferation of vaccinations is actually contributing to the loss of Herd Immunity, replacing the more effective natural resistance with less effective artificial resistance, and that we are just now getting to the point in our population where significant numbers of people who had gotten the actual disease are now starting to be lower than people who have not, but had the vaccination. Leolore (talk) 07:05, 11 February 2015 (UTC)


 * Just because dissenting views exist doesn't mean said views should be included. Including anti-vaccination opinions on this article would violate Wikipedia's policy of neutrality, specifically rules relating to due and undue weight, fringe theories, balance, and pseudoscience. If one wants to add any information into this article, then it should be reliably sourced, meaning that it must also be verifiable. & as I said before, Wikipedia should not be a public opinion venue on medical issues. Medical articles should reflect current scientific consensus so as to ensure that the public is well informed. ComfyKem (talk) 09:30, 11 February 2015 (UTC)

definition of the term?
it seems the page is describing how we try to achieve herd immunity, not what it actually is? The uneditable top section reads

"Herd immunity or herd effect, also called community immunity, describes a form of immunity[1] that occurs when the vaccination of a significant portion of a population (or herd) provides a measure of protection for individuals who have not developed immunity.[2] Herd immunity theory proposes that, in contagious diseases that are transmitted from individual to individual, chains of infection are likely to be disrupted when large numbers of a population are immune or less susceptible to the disease. The greater the proportion of individuals who are resistant, the smaller the probability that a susceptible individual will come into contact with an infectious individual.[3]"

seems it should read more like ... Herd immunity or herd effect, also called community immunity, describes a form of immunity[1] that occurs when a significant portion of a population (or herd) is immune, providing a measure of protection for individuals who have not developed immunity. [2] Herd immunity theory proposes that, in contagious diseases that are transmitted from individual to individual, chains of infection are likely to be disrupted when large numbers of a population are immune or less susceptible to the disease. The greater the proportion of individuals who are resistant, the smaller the probability that a susceptible individual will come into contact with an infectious individual.[3] — Preceding unsigned comment added by 207.216.63.191 (talk) 00:03, 18 January 2015 (UTC)
 * For clarity, I took the liberty of striking out the part of the lead that is the same in both versions. Meters (talk) 00:12, 18 January 2015 (UTC)
 * The first sentence might be improved by a bit of tweaking, but since we're discussing the public health aspect of herd immunity I think it's important that we still mention vaccination. Meters (talk) 00:32, 18 January 2015 (UTC)

No critics mentioned
There is no mention of expert critical response on this theory in practice. Please complete. --Imhotepie (talk) 10:59, 15 November 2016 (UTC)

rewrite
I've rewritten this article to do several things: 1) to correct inaccurate information, 2) to expand existing information, and 3) to include information that was not included. I searched through a lot of medical articles to make this change, so the article should closely reflect current consensus on this topic. Also, all past discussions on this talk page have been archived. I've temporarily removed the basic reproduction number table; it will be re-added shortly after I make some changes to it. ComfyKem (talk) 09:05, 13 March 2015 (UTC)


 * Why did you blank the talk page? SW3 5DL (talk) 18:39, 13 March 2015 (UTC)

I've done some more reading and found some things I could touch on more and some small changes that could be made, so I will be making another major edit to this article sometime in the near future. I hope to complete this by the end of the month, and I believe that this article could be at least GA afterwards. We'll see. ComfyKem (talk) 11:09, 19 March 2015 (UTC)

The major edit previously mentioned is done. About images, there could be an image added illustrating vaccine effectiveness in the form of one of those before and after introduction charts. I'd also like to add a picture of ring vaccination to the History section, but I couldn't find one with adequate licensing to use here. Most herd immunity images are different forms of the same thing, and we have 1 of these images as the lead image, so I think that even after more images are added this article is still likely to seem under-illustrated. ComfyKem (talk) 02:24, 25 March 2015 (UTC)


 * The article reads much better now. Well done. Check the CDC for a free image. Also the U.S. Public Health Service, and likely many state public health departments have their own images. These should be free usage. SW3 5DL (talk) 20:04, 25 March 2015 (UTC)

Comments
Article is well done. Made a few minor changes. A few more comments:
 * Infants also get immunity from breastfeeding during the first few months of life
 * Should we mention smallpox and polio in the lead? Doc James  (talk · contribs · email) 10:24, 2 April 2015 (UTC)


 * The passive immunity subsection has a sentence that refers to breastfeeding: After birth, newborns can also acquire these antibodies from colostrum. If that's not good enough then you're free to reword it. & I changed the ref for the smallpox sentence you added and expanded it to cover other diseases. ComfyKem (talk) 14:50, 2 April 2015 (UTC)

Inaccuracies in HIT numbers?
I checked the source given for the R0 numbers and HIT numbers of the various diseases. The R0 values appear to be correct, but the HIT numbers differ from the one on the source. IE, Measles' HIT is stated to be 83-94% instead of 92-95%, Diphtherias HIT is stated to be 83-86% instead of 85%, etc. — Preceding unsigned comment added by 130.179.244.141 (talk) 17:50, 10 November 2015 (UTC)

Content
This was added "The effects of herd immunity can be examined within the history of the chickenpox vaccine. Since its’ debut in 1995, the death rate among children and infants dropped significantly by about 97%. Between 2004 and 2007, no infants died of chickenpox due to the mass vaccination of adults and young children. Because of herd immunity, the disease was contained and indirectly protected infants who were too young to receive the vaccination."

The ref however does not support any of that? It does not mention 2004, 2007 or 97%? Ref actually says "Although controlled trials confirm approximately 100% relative risk reduction for severe disease, no deaths have been reported for subjects in either vaccine or placebo groups. No trial to date has had sufficient power to examine this outcome" Doc James  (talk · contribs · email) 02:23, 28 November 2015 (UTC)