Perhaps the weak link in the effectiveness of vaccines is public acceptance. Individual vaccine types vary in terms of their effectiveness, but all are reasonably effective and very safe. Vaccines are, in my opinion, one of the “home runs” of modern medicine – scientists hit upon a way to marshal our own immune systems to make us resistant or even completely immune to certain infectious diseases. The result has been a dramatic decrease in diseases that used to plague humanity, and the complete eradication of one (smallpox).
It is ironic that the greatest barrier to the effectiveness of the vaccine program is public acceptance. Part of the problem is that very high acceptance is needed in order to achieve what is called “herd immunity” – where there is sufficient protection in the population that an infected individual will likely not cause an outbreak.
In the US the numbers are pretty good, and have remained so even through the recent increase in the anti-vaccine movement. About 68% of children complete the full routine vaccination series. Many of the individual vaccines have compliance rates in the 90s (MMR, for example, was 92.1% in 2008). The level required for herd immunity varies, but it is generally around 85-90%.comments (38)