And now vaccine resistance is spreading among parents who want to free ride on the herd immunity of others.

FORBES: More Measles Outbreaks Due to Decreasing Vaccination Rates

No cattle vaccine is available, and one with the ability to provide near whole herd immunity is years away.

BBC: Cull 'not good deal' for taxpayer, says UK expert

All immunisation is intended to benefit the wider population as well as the individual through what is known as herd immunity.

BBC: Flu vaccines for all children

Vaccination levels plunged as low as 80% in the U.K., according to BMJ, well below the 95% needed to insure herd immunity.

FORBES: Thimerosol-Autism Link Was A Legal Theory In Search Of Science

If we maintain what is called "herd immunity", then even if there is an outbreak, it will not spread and become an epidemic.

BBC: Steve Jobs waits on stage, AP

As things stand, the Mac community has no herd immunity because most users seem to assume that they don't need to take preventive action.

BBC: Steve Jobs waits on stage, AP

The vaccine needs a 95% uptake to achieve the herd immunity needed to ensure the disease cannot take a hold in individuals who are not vaccinated.

BBC: Measles outbreak 'worst in years'

Yea, that study that actually tested all other conceivable factors, performed a detailed analysis, replicated the analysis among multiple populations and proved conclusively that herd immunity can be conferred in the population if 95% of it is vaccinated.

FORBES: Anti-Vaccine Movement Causes The Worst Whooping Cough Epidemic In 70 Years