Antibody induced by one-dose varicella vaccine soon became weak in children: evidence from a cross-sectional seroepidemiological survey in Beijing, PRC

Abstract

Background: Numerous post-licensure studies, mostly from field epidemiological evidences such as outbreak surveys, have demonstrated the effectivenesss and insufficiency of one-dose varicella vaccine in outbreak control. Serological evidence of immunization failure is, however, relatively less reported in contrast. A cross-sectional seroepidemiological survey of Beijing residents was performed in 2012 in the People's Republic of China, after the one-dose varicella vaccine had been widely used for several years.

Methods: Multistage stratified random sampling method was designed to recruit 2 144 subjects. The ELISA method was used to test the present blood samples collected and the reserve samples collected in 2008 to assess the trends of anti-VZV seroprevalence in the past 5 years and to determine the risk factors for varicella infection.

Results: The age- and sex- adjusted overall anti-VZV seropositivity of Beijing residents in 2012 was 84.5%. Two groups' adjusted overall anti-VZV seroprevalence in 2012 showed obvious growth compared with 2008 (<1 yr old: from 6.3% to 16.9%; 1-4 yr old: from 27.6% to 57.2%). Reported one-dose vaccination history was 71.6% (149/208), 80.9% (182/225) and 82.2% (180/219) in the 1-4 yr, 5-9 yr, 10-14 yr age groups, respectively. Of subjects who had received the one-dose vaccine, 36% (216/603) showed negative anti-VZV concentrations (<110 mIU/mL); additionally 15.9% (96/603) of such subjects' anti-VZV concentrations were in the lowest positive concentration group (110-299 mIU/mL). Seropositivity in permanent residents of 1-9 yr old with verified vaccination was merely 61.8%. Various age groups (1-3 yr, 4-6 yr, and 7-9 yr) all showed seropositivity that gradually decreased with increasing of the interval between vaccination and blood sampling.

Conclusion: Mass varicella vaccination significantly improved the immunity of younger Beijing residents. However, vaccine-induced anti-VZV antibody soon became weak in children with high coverage (approximately 80%) after vaccination for several years which is significantly higher than reported in pre-licensure studies. A government-funded 2-dose immunization program with mandatory vaccination schedule for Beijing residents may need consideration in the near future.

Fig. 1

Distribution curves of anti-VZV concentration of Beijing residents in 2012 by a age group, b gender and c vaccine vaccination (n = 2157). There were statistically significant differences in anti-VZV concentrations between age groups (P < 0.001) and vaccination status (P < 0.001), but no difference between gender (P = 0.221), by x ² test

Fig. 2

Seroprevalence of 1-9 years permanent Beijing residents in 2012 who denied varicella history and had received one dose vaccine based on verified vaccination records. Distribution of different age groups by different between vaccination and blood sampling interval (n = 165)