The problem of clustered drops in herd immunity
September 30, 2015 1 Comment
There are many reasons anti-vaccine lobbyists push the falsehood that herd immunity “is a myth”, is not important or simply doesn’t exist.
To listen to recent untruths from Meryl Dorey, one should eagerly accept that it is “documented” in peer reviewed literature as being more or less non-existent. Indeed, “it is a lie” lies Dorey. By essentially mocking the importance of herd immunity, garden variety anti-vaccine tricksters can shirk the responsibility that not vaccinating may harm the wider community, innocent infants or children, and deny larger scale resistance to infection that the immune-compromised rely on.
Herd immunity is an impressive function of mass vaccination. More so it is remarkably easy to understand. But the anti-vaccine lobby refuse to accept any need for or benefit from, mass vaccination. It is even more bizarre when one considers the parallels to so-called “natural immunity” – such as with marvellous measles, or “right of passage” infection and immunity. With mass vaccination we can control the spread of immunity and thus the spread and ultimate impact of vaccine preventable disease.
We should never forget that claims of raising impeccably healthy and disease-free unvaccinated children can exist only for as long as vaccine-induced herd immunity remains at a crucial level. The level that permits a free ride and protection from most vaccine preventable diseases for these very children.
Once again the formula frequently relied upon is “< 100% = 0%” – such as this 1973 article. One popular mode is that if a child is vaccinated against X, they should be safe from infection with X. Even worse is a distortion of epidemiological factors at play. This involves citing nationwide or statewide vaccination rates – which level out as reasonably high – along with reported outbreaks, such as those seen of pertussis or measles. Or including individuals who have had just one MMR jab (in the case of measles) or those whose vaccine-induced pertussis immunity has certainly waned.
This not-very-clever deception ignores the fact that areas with low vaccination uptake provide the ideal conditions for infection to spread rapidly.
The video below compares the difference in infection spread in the sparsely located unvaccinated compared to a cluster of unvaccinated individuals.