Global Health Now: The Myth about Herd Immunity

11 December, 2019

This article in Global Health Now highlights the myth about 'herd immunity'. Extracts and a comment from me below. Full text here: https://www.globalhealthnow.org/2019-12/myth-about-herd-immunity

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One common argument some parents make for declining vaccines for their children is that vaccines are not necessary — that their children are unlikely to get sick even if they are not vaccinated. Perversely, this argument relies in part on parents’ confidence that many other children are being vaccinated, creating “herd immunity” that makes it difficult for outbreaks to spread. In other words, if all my neighbors’ children get vaccines, my own unvaccinated children will benefit from the protection of the herd. But what happens if several neighbors also decline vaccines for their children?...

Typically, 93% to 95% of a population must be vaccinated to achieve herd immunity and prevent an outbreak of measles... Relocation, travel or even a new circle of friends can change the composition of one’s herd, and thus its shared protection against infection.

Such a scenario unfolded in December 2015, when several thousand visitors to a California amusement park were exposed to measles. In total, 147 people were infected — most of whom were unvaccinated. In a scenario like this, where close contact with an infected individual occurs, the last line of defense is an individual’s own immunity to the disease...

A good place to start is by dispelling the myths about herd immunity—explaining to parents how herd immunity works, and when it doesn’t, and ensuring they understand the consequences to the larger community of the supposedly “individual” choice to forgo or delay immunizations...

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Comment (NPW): It seems to me that the medical profession is at least partly to blame for this false belief, by using the misleading term 'herd *immunity*' (my emphasis). The term 'herd immunity' continues to be widely used and clearly causes confusion. According to Wikipedia, the term was first used in 1923. https://en.wikipedia.org/wiki/Herd_immunity A century later, a different term should perhaps be used to avoid continued confusion. What do you think?

Best wishes, Neil

Coordinator, HIFA Project on Information for Citizens, Parents and Children

http://www.hifa.org/projects/citizens-parents-and-children

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HIFA profile: Neil Pakenham-Walsh is coordinator of the HIFA global health campaign (Healthcare Information For All - www.hifa.org ), a global community with more than 19,000 members in 177 countries, interacting on six global forums in four languages. Twitter: @hifa_org FB: facebook.com/HIFAdotORG neil@hifa.org