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Varicella zoster virus (VZV) infection.

Lier, E.A. van, Boot, H.J., Kemmeren, J.M., Luytjes, W., Stirbu-Wagner, I., Rots, N.Y., Melker, H.E. de. Varicella zoster virus (VZV) infection. In: T.M. van 't Klooster; H.E. de Melker. The National Immunisation Programme in the Netherlands: developments in 2011. Bilthoven: RIVM, 2011. p. 71-76.
This report presents the developments of the National Immunisation Programme (NIP) in 2011, supported by updated surveillance data on current and potential target diseases. For many years, the participation level in the NIP has been high, which resulted in low incidences for most target diseases in 2011, i.e. diphtheria, tetanus, poliomyelitis, Haemophilus influenzae type b disease, rubella and meningococcal serogroup C disease. As in previous years, the NIP was effective and safe in the reporting period. Continuous monitoring is needed to further optimise the programme.

Pertussis, pneumococcal disease and meningococcal C disease
In 2010, the number of pertussis cases in young children was reduced due to the switch from whole-cell to acellular vaccine in 2005. The protective effect of the preschool booster introduced in 2001 at 4 years of age remained visible up to 13 years of age. In contrast, the incidence of pertussis has been increasing in adolescents and adults since 2004. The decrease in the number of cases of invasive pneumococcal disease (IPD) was caused by a decrease in the incidence of vaccine types in the vaccinated cohorts (87 percent in children < 2 years of age) and to a lesser extent in other age groups. However, this effect is partly counterbalanced by the increased incidence of non-vaccine types due to type replacement. On 1st March 2011, the 10-valent pneumococcal vaccine replaced the 7-valent vaccine. In 2009 and 2010, the first two cases of meningococcal group C disease in previously vaccinated persons were reported since the introduction of vaccination in 2002. Both persons had an immune disorder.

Hepatitis B
For hepatitis B the number of cases in 2010 was 8 percent lower than in 2009, mostly due to the decreasing number of acute HBV notifications in men who have sex with men (MSM). This suggests that the targeted vaccination programme introduced in 2002 has been effective. From birth cohort August 2011 onwards, a universal infant HBV vaccination has been included in the NIP.

Measles, mumps and human papillomavirus (HPV)
In Western Europe, the incidence of measles that increased in 2010 and 2011 reflected an increase in the number of imported cases in the Netherlands in 2011. The mumps outbreak that started among the highly vaccinated student population in late 2009, continued throughout 2010 and 2011. In 2011, interim vaccination coverage for three doses HPV vaccine in the first cohort of 12-yearold girls was 52.5 percent; the coverage among girls for the catch-up campaign increased from 47 percent to 52.3 percent.

Future candidates
With regard to potential new target diseases, it is noteworthy that the incidence of meningococcal serogroup B disease has further decreased every year since 2001. The incidence of rotavirus associated gastroenteritis, however, continued to rise in 2010. In 2010, the number of hepatitis A cases increased to the level of 2006 (1.6 cases per 100,000 inhabitants). For varicella and herpes zoster no striking changes occurred in 2010.

Safety
There were no unusual reports in the past year regarding the safety of the vaccines used in the NIP.