PAEDIATRIC AND NEONATAL INFECTIONS: Edited by Paul T. HeathVaccination and herd immunity: what more do we know?Rashid, Harunora; Khandaker, Gulama; Booy, Roberta,bAuthor Information aNational Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases (NCIRS), The Children's Hospital at Westmead and The University of Sydney bThe Sydney Institute for Emerging Infections and Biosecurity (SEIB), Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia Correspondence to Professor Robert Booy, National Centre for Immunisation Research and Surveillance of Vaccine Preventable Disease, The Children's Hospital at Westmead, Cnr Hawkesbury Road and Hainsworth St, Locked Bag 4001, Westmead, NSW 2145, Australia. Tel: +612 9845 1415; fax: +612 9845 1418; e-mail: firstname.lastname@example.org Current Opinion in Infectious Diseases: June 2012 - Volume 25 - Issue 3 - p 243-249 doi: 10.1097/QCO.0b013e328352f727 Buy Metrics Abstract Purpose of review This review summarizes herd immunity, focusing on conceptual developments with application to vaccination programs. Recent findings The conventional idea of herd immunity is based on the relationship between the transmission dynamics of infectious agents and population immunity. However, there have been some recent conceptual developments in vaccine ‘herd immunity’ or ‘herd protection’ that address the complexities of imperfect immunity, heterogeneous populations, nonrandom vaccine uptake and ‘freeloaders’. Some vaccines may provide better protection than others; for instance, meningococcal conjugate vaccines are superior to polysaccharide vaccines, as is true of pneumococcal and Haemophilus influenzae type b vaccines. Achieving a very high uptake rate should be the target for certain vaccines, for example, measles vaccine, in order to prevent the disease effectively. Emerging issues, for example, waning of immunity after pertussis vaccination, are fresh challenges. Summary Herd immunity is a complex issue inherent to a vaccine and the population receiving the vaccine. We have more to learn and apply. © 2012 Lippincott Williams & Wilkins, Inc.