TY - JOUR
T1 - Nasopharyngeal colonization
T2 - A target for pneumococcal vaccination
AU - Käyhty, Helena
AU - Auranen, Kari
AU - Nohynek, Hanna
AU - Dagan, Ron
AU - Mäkelä, Helena
AU - Jokinen, Jukka
AU - Kilpi, Terhi
AU - Lucero, Marilla
AU - Tallo, Veronica
AU - Madhi, Shabir
AU - Adrian, Peter
AU - Klugman, Keith
AU - Goldblatt, David
AU - Scott, Anthony
AU - O'Brien, Kate
AU - Mulholland, Kim
AU - Russel, Fiona
PY - 2006/10/1
Y1 - 2006/10/1
N2 - The pneumococcal conjugate vaccine (PCV), licensed in 2000, is highly efficient in preventing serious disease caused by serotypes in the vaccine and also prevents symptomless colonization of the nasopharynx. Prevention of this first step in the infection cycle has important consequences: it reduces chances of spread of the infection and indirectly protects from disease. Through these indirect effects, the protection afforded by the vaccine extends to the whole population, including those not vaccinated (herd immunity). Already now, after 5 years of wide use of PCV for infant immunization in the USA, more cases are prevented through the indirect effects than by vaccine-induced immunity in those vaccinated. The extended protection increases the cost-effectiveness of PCV and should clearly encourage its use in poorly resourced countries. However, the accumulated experience also shows that the herd immunity, due to PCV, is partly offset by replacement of the vaccine serotypes by other, nonvaccine serotypes. Owing to the general reduced virulence of the latter, this has only had a modest effect on disease, but the possibility of more virulent nonvaccine serotypes arising cannot be ignored and should be the focus of continued surveillance.
AB - The pneumococcal conjugate vaccine (PCV), licensed in 2000, is highly efficient in preventing serious disease caused by serotypes in the vaccine and also prevents symptomless colonization of the nasopharynx. Prevention of this first step in the infection cycle has important consequences: it reduces chances of spread of the infection and indirectly protects from disease. Through these indirect effects, the protection afforded by the vaccine extends to the whole population, including those not vaccinated (herd immunity). Already now, after 5 years of wide use of PCV for infant immunization in the USA, more cases are prevented through the indirect effects than by vaccine-induced immunity in those vaccinated. The extended protection increases the cost-effectiveness of PCV and should clearly encourage its use in poorly resourced countries. However, the accumulated experience also shows that the herd immunity, due to PCV, is partly offset by replacement of the vaccine serotypes by other, nonvaccine serotypes. Owing to the general reduced virulence of the latter, this has only had a modest effect on disease, but the possibility of more virulent nonvaccine serotypes arising cannot be ignored and should be the focus of continued surveillance.
KW - Indirect effects of vaccination
KW - Invasive pneumococcal disease
KW - Pneumococcal carriage
KW - Pneumococcal colonization
KW - Pneumococcal conjugate vaccines
KW - Pneumococcus
UR - http://www.scopus.com/inward/record.url?scp=33845895724&partnerID=8YFLogxK
U2 - 10.1586/14760584.5.5.651
DO - 10.1586/14760584.5.5.651
M3 - Review article
C2 - 17181439
AN - SCOPUS:33845895724
SN - 1476-0584
VL - 5
SP - 651
EP - 667
JO - Expert Review of Vaccines
JF - Expert Review of Vaccines
IS - 5
ER -