Biology Now, 2e

In 1999, the United Kingdom began a meningitis vaccination

program for children up to the age of 18. Meningitis rates

rapidly fell off throughout the population—children and adults

alike—thanks to both the effectiveness of the vaccine and

the protective effects of herd immunity. Models show that

without herd immunity, the number of meningitis cases would

have rebounded. The U.S. CDC recommends meningitis

vaccination up to the age of 23, as outbreaks have been

reported on college campuses in recent years.

Safety in Numbers

Meningitis cases in

England and Wales

19 years old

and younger

20 years old

and older

Observed cases

Predicted cases

(with herd immunity)

Predicted cases

(no herd immunity)

1999 2001 2003 2005 2007 2009

0

200

400

600

800

1,000

1995 1997 1999 2001 2003 2005 2007

0

200

400

600

800

1993

Prevaccination Postvaccination

Postvaccination

Assessment available in