Laboratory investigations of vaccinated patients with varicella.
BACKGROUND
Accompanying varicella vaccination in children in Germany recommended with one (2004) and two (2009) doses, sentinel surveillance of varicella with a sample (n∼900) of private physicians was established in 2005. Physicians reported monthly aggregated data on all varicella cases and case-based on vaccinated patients, of whom skin lesion samples were laboratory investigated to identify varicella-zoster virus (VZV). We analyzed the impact of vaccination frequency on the number of cases and on laboratory results within the sentinel.


METHODS
Swabs were obtained with a Teflon tip and sent together with a case-based questionnaire to the reference laboratory. VZV wild-type and vaccine-type was identified by polymerase chain-reaction (PCR) and pyrosequencing methods. Case-based data and laboratory results were analyzed descriptively.


RESULTS
From April 2005 to March 2014, of all monthly reported cases (n=111,456) 4789 were vaccinated and eligible for further analysis. No differences were found between laboratory investigated and not investigated cases (1017 vs. 3772) except that the proportion of cases vaccinated twice was higher in lab-cases (29.4% vs. 16.1%). PCR remained negative in 69.6% (197/283) of breakthrough-cases vaccinated twice, in comparison to 22.7% (147/649) breakthrough-cases vaccinated once. VZV was confirmed in 500 (81) patients with breakthrough varicella after one (two) vaccination(s); identification of VZV wild-type, vaccine-type, or no further differentiation was possible in 485 (72), 5 (6), and 10 (3) cases, respectively.


CONCLUSIONS
Varicella breakthrough disease is rare in Germany and suspected clinical cases require laboratory confirmation. The lower confirmation rate of VZV after two vaccine doses suggests a better protection compared to one dose.
Robert Koch-Institute, Department for Infectious Disease Epidemiology, Berlin, Germany. Electronic address: siedlera@rki.de.
Anette
A
Siedler
Robert Koch-Institute, Department for Infectious Disease Epidemiology, Berlin, Germany.
Marleen
M
Dettmann
Robert Koch-Institute, Department for Infectious Disease Epidemiology, Berlin, Germany.
Kristin
K
Tolksdorf
Technical University Dresden, Dresden, Germany.
Carolin
C
Polte
Robert Koch-Institute, Department of Infectious Diseases, Berlin, Germany.
Cornelia
C
Walter
Robert Koch-Institute, Department of Infectious Diseases, Berlin, Germany.
Bernhard
B
Ehlers
D002644:Chickenpox / Q000453:epidemiology* / Q000266:history / Q000276:immunology*; D019433:Chickenpox Vaccine / Q000276:immunology; D005260:Female; D005858:Germany / Q000453:epidemiology; D014645:Herpesvirus 3, Human / Q000145:classification / Q000235:genetics; D049674:History, 21st Century; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011159:Population Surveillance; D014611:Vaccination
D019433:Chickenpox Vaccine
Breakthrough varicella; Vaccine-type virus; Varicella Zoster virus; Varicella vaccination; Wild-type virus