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Background Low vaccination rates and under-detection of pertussis infections in adolescents and young adults have an impact on the transmission of pertussis to infants. In this study, the proportion of adolescents and young adults with IgG antibodies against B. pertussis antigens, representing recent infection or vaccination, was estimated in a population-based probabilistic survey in Mexico. Methods Sera and data from 1,581 subjects, including 1,102 adolescents and 479 young adults (10–19 and 20–25 years old, respectively) randomly selected from Mexico’s 2012 National Health and Nutrition Survey, were analyzed. IgG antibodies against pertussis toxin (PT) were measured with the CDC/FDA ELISA. A subset of 234 samples was additionally tested with Bp-IgG PT ELISA kit (EUROIMMUN AG, Lubeck, Germany). Threshold values from corresponding test kits were used to identify recent infection or vaccination. Results Overall anti-PT IgG seroprevalence was 3.9% (95% CI: 2.3–6.3); 3.1% (95% CI: 1.9–5.0) in adolescents, and 4.9% (95% CI: 2.2–11) in young adults. Seroprevalence did not significantly vary by sex, socioeconomic status, region or rural/urban location. Compared to the CDC/FDA ELISA, the EUROIMMUN test showed a 76% sensitivity and 88% specificity. The weighted estimates represent a considerable burden of recent infection in adolescents and young adults; however, most adolescents and adults were seronegative and, therefore, susceptible to pertussis infection. Conclusion Since booster vaccination to B. pertussis after toddlerhood is not recommended in the Mexican national policy, anti-PT IgG seropositivity may be reasonably attributed to recent infection. Assessing pertussis seroprevalence requires careful consideration of the diagnostic test threshold interpretation and epidemiological model used.

Purpose In April 2007, Panama introduced Hepatitis A universal vaccination using a two-dose schedule (Havrix® junior; GSK Vaccines, Belgium). We assessed the impact of this hepatitis A vaccine three years after it was recommended for universal mass vaccination in Panama. Materials and methods Hepatitis A vaccination impact was assessed using two different approaches. The first approach used retrospective data (incidence and number of cases for all age groups), collected from the passive surveillance of the Epidemiologic Surveillance System of the Ministry of Health of hepatitis A and unspecified hepatitis before (2000–2006) and after (2008–2010) introduction of hepatitis A vaccine. The second approach was a prospective hospital-based active surveillance for hepatitis cases conducted in subjects (0–14years) during 2009–2011 at three sentinel hospitals in Panama. Results Overall, the annual incidence of hepatitis A and unspecified hepatitis in 2008, 2009 and 2010 were 13.1, 7.9 and 3.7 per 100,000 subjects, lower than the baseline incidence of 51.1 per 100,000 subjects. In comparison to the mean baseline period (2000–2006), there was an 82% mean reduction in the overall hepatitis-related outcomes (hepatitis A and unspecified hepatitis) after vaccine introduction (2008–2010) in all age groups. In the hospital-based surveillance (2009–2011), of the 42 probable viral hepatitis A cases, nine cases were confirmed as acute hepatitis A (8 in 2009, 1 in 2010). Of these confirmed cases, two belonged to the targeted vaccine group (1–4 years) but were not vaccinated. Conclusions Our study suggests that the introduction of two-dose hepatitis A vaccines in Panama has contributed to the reduction in the incidence of overall hepatitis-related outcomes for all age groups, suggesting herd protection. Additional monitoring is required to document a sustained long-term effect.

Transmission of excreted vaccine-derived infectious virus from vaccinated to unvaccinated individuals is possible within close contacts. This randomized (1:1), double-blind study evaluated the potential for transmission of human rotavirus vaccine strain, HRV (Rotarix™) from vaccine recipients to unvaccinated close contacts (twins). 100 pairs of healthy twins aged 6–14 weeks at the time of Dose 1 of HRV vaccine/placebo were enrolled and one randomly selected twin from each pair received two vaccine doses and the other received placebo doses (at 2 and 4 months of age). Presence of vaccine strain in the stool samples of placebo recipients was an indicator of transmission. Serial stool samples were tested for rotavirus using ELISA at pre-determined time points; rotavirus positive stool samples were tested with RT-PCR and reverse hybridization assay to identify G1P[8] vaccine strain. If G1P[8] vaccine strain was detected, the complete genome was sequenced to assess the similarity between viral isolates. Immunogenicity and safety of HRV vaccine in transmission cases was assessed. 15 transmission cases were reported in 80 evaluable twins who received placebo and the transmission rate was 18.8% (95% CI: 10.9–29.0%). None of the transmission cases was associated with gastroenteritis symptoms. Anti-rotavirus IgA seroconversion was 62.5% (95% CI: 51.0–73.1%) (HRV) and 21.3% (95% CI: 12.9–31.8%) (placebo) 7-weeks post-Dose 2; seroconversion in transmission cases was 26.7% (95% CI: 7.8–55.1%). Genetic variations or amino acid substitutions in transmission cases were similar to that seen in corresponding vaccine recipients. Transmission of HRV vaccine strain to unvaccinated twins living in close contact occurred, however, they were not associated with increased of gastroenteritis. Whether transmission leads to indirect protection among unvaccinated individuals remains unknown at this stage.

We estimated the seroprevalences of varicella-zoster virus (VZV), herpes simplex virus (HSV) and cytomegalovirus (CMV) in this cross-sectional database study. Serum samples collected during the National Health and Nutrition survey (ENSANUT 2006) were obtained from subjects aged 1-70 years between January and October 2010. Serological assays for the determination of antibodies against VZV, HSV and CMV were performed. The overall seroprevalences of VZV, HSV-1, HSV-2 and CMV were 85.8%, 80.9%, 9.9% and 89.2%, respectively. Seroprevalences of VZV, HSV-1 and CMV were comparable between males and females. For HSV-2, although the seroprevalence rate was higher in females when compared to males, this difference in seroprevalence was not statistically significant. Seroprevalence rates for VZV, HSV-1, HSV-2 and CMV increased with age (p-value

This paper presents the results of four separate phase III trials, which assessed the immunogenicity and reactogenicity of DTPw-HBV/Hib 2.5 in comparison with licensed Tritanrix-Hep B (GlaxoSmithKline Biologicals) and Hiberix (10 microg PRP), given as separate or mixed injections (3 trials) or with or without hepatitis B vaccine at birth (1 trial). The immunogenicity of DTPw-HBV/Hib 2.5 was non-inferior to the reference vaccine regimen in terms of seropositivity rates. The overall reactogenicity profile of DTPw-HBV/Hib 2.5 was also similar to that of the reference vaccine regimen. These results confirm the previously established immunogenicity and safety of reduced dose PRP conjugated vaccine regimens.