Effect of the interval between birth and second dose of hepatitis B vaccine on perinatal transmission of hepatitis B virus.

Preventing perinatal transmission is important for hepatitis B (HepB) elimination. We conducted a retrospective cohort study to assess the interval between HepB birth-dose (HepB-BD) to second-dose (HepB-SD) vaccination on perinatal transmission. Among 39,313 infants born to HepB s-antigen (HBsAg)-positive mothers from a Korean national database 38,411 (97.7%) had completed timely immunophylaxis with HepB-BD 41,572 (99.8%) with hepatitis B immune globulin, and 1027 (2.6%) were HBsAg-positive at ≥ 9 months. Maternal factors (i.e. HepB e-antigen status, age, or nationality) were associated with an increased risk of infection whereas short gestational length decreased it. The HepB-BD - HepB-SD interval (<8 vs. ≥8 weeks) did not alter the risk.

High coverage and timeliness of vaccination of children under 6 years of age in Risaralda, Colombia.

This study determined the coverage and timeliness of immunization in children <6 y from Risaralda, Colombia. A retrospective cross-sectional study evaluated data from a vaccination coverage and timeliness verification survey conducted in 2019, including 2457 children <6 y from Risaralda, Colombia. Variables included demographics, a record of vaccinations included in the Colombian Vaccination Plan, and date of immunization. Vaccination was defined as timely until 29 d after the day established by the plan. Coverage was over 95% for all vaccinations, except the boosters of diphtheria/pertussis/tetanus (DTP) and oral polio at 18 months (91.0%), influenza (85.6%), and yellow fever (49.2%). Most surveyed children demonstrated very high timeliness of vaccination, with values close to, or over, 90%, although there were exceptions for pentavalent (DTP+Haemophilus influenzae type B+hepatitis B) and polio vaccines at 6 months (79.4%), influenza (85.6%), and yellow fever (49.2%). Before the COVID-19 pandemic, Colombian Vaccination Plan demonstrated high coverage and timeliness of vaccination of children <6 y of age; however, timeliness for the third dose of DTP-Hib-HBV and polio showed opportunities for improvement.

Pertussis in Mexico from 2000 to 2019: A real-world study of incidence, vaccination coverage, and vaccine effectiveness.

BACKGROUND: The national immunization program in Mexico includes a 3-dose primary series of pertussis vaccine and a toddler booster dose. In Mexico, whole-cell pertussis vaccines (wP) were switched in 2007 to acellular pertussis vaccines (aP). METHODS: This retrospective study using Mexican National Databases of Health and population surveillance (2000-2019) assessed the incidence of pertussis, infant pertussis vaccination coverage, and vaccine effectiveness (VE) against clinically-diagnosed and/or laboratory-confirmed pertussis in children aged 6.5-18.5 or 24.5 months for the primary series, and children aged 18.5 or 24.5-48.5 months for the toddler booster. RESULTS: The incidence of pertussis sharply increased in 2012 and was highest in 2012, 2015, and 2016 (0.84-0.94/100,000 person-years). Coverage was highest for the first dose in the primary series, decreasing for each subsequent dose. The VE against notified pertussis was 96.4% (95% CI: 94.7, 97.6) for the first three doses of wP vaccine (2000-2007) and 95.7% (95% CI: 95.1, 96.2) for the first three doses of aP vaccine (2008-2019). CONCLUSIONS: Our findings suggested high levels of vaccine effectiveness overall were achieved for the aP and wP vaccines in Mexico between 2000 and 2019.

Infant vaccination against pertussis in Argentina: Parent-reported outcomes on reactogenicity, impact on daily routine and satisfaction after pentavalent whole-cell or hexavalent acellular pertussis vaccines.

Introduction: In Argentina, a pentavalent whole-cell pertussis vaccine (wP) is used in the National Immunization Program, however hexavalent acellular pertussis (aP) vaccines are available in the private market. Objective: To describe parent or guardians perceptions on reactogenicity, daily routine and satisfaction after a first or third dose of a wP-pentavalent plus IPV (wP-group) or the fully-liquid aP-hexavalent vaccine (aP-group) in infants. Material and methods: This was a prospective observational and analytical study. Parents or guardians of infants born at term attending a public or private vaccination center in Buenos Aires City were invited to participate. All parents or guardians had completed 12-year schooling and were asked to fill out an online 7-day post vaccination questionnaire. The questionnaire was validated as the first phase of the study. Descriptive analysis of study variables was carried out, REDCap was used for the online survey, and STATA 14 for data analysis. Results: 1071 parents or guardians answered the questionnaire (response rate 82%), 530 for wP-group and 541 for aP-group.Local and systemic adverse reactions, in groups wP and aP respectively, were: pain 83%, 28%; swelling 63%, 16%; redness 52%, 22%; irritability 72%, 52%; fever 37%, 8%; loss of appetite 36%, 19%; drowsiness 38%, 27%; and vomiting 15%, 11%.Impact on daily life: social activities 36%, 20%; routine 48%, 24%; mood 39%, 23%; vitality 47%, 24%; sleep 50%, 30%; and appetite 22%, 7%.Parents were satisfied with the vaccination process in 96% and 98% for wP-group and aP-group respectively. Parents reported willingness to bring infant for future vaccine doses in 97% and 99% for wP-group and aP-group respectively. Conclusions: Reported reactogenicity and impact on family daily routine was higher in infants receiving wP-pentavalent than aP-hexavalent vaccines. Parents in both groups conveyed vaccine acceptance and positive intentions for future immunizations.

Prenatal tetanus-diphtheria-acellular pertussis vaccine effectiveness at preventing infant pertussis.

OBJECTIVE: To evaluate the effectiveness of the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine containing five pertussis components (Tdap5; Adacel®, Sanofi) when given during pregnancy at preventing pertussis in infants less than 2 months of age. METHODS: The US Centers for Disease Control and Prevention (CDC), in collaboration with the Emerging Infections Program (EIP) Network, undertook a case-control study evaluating the effectiveness of Tdap vaccination in pregnancy against pertussis in infants less than 2 months of age based on data collected by the EIP Network from 2011 through 2014. The dataset from the CDC/EIP Network study was used to conduct this product-specific vaccine effectiveness analysis of Tdap5 vaccination in pregnancy to prevent disease in young infants. The main outcome of interest was vaccine effectiveness in infants whose pregnant parents were vaccinated with Tdap5 between 27 and 36 weeks' gestation, in accordance with the ideal timing for Tdap vaccination in pregnancy recommended by the US Advisory Committee on Immunization Practices. Odd ratios (ORs) and 95 % confidence intervals (CIs) were estimated using conditional logistic regression, and vaccine effectiveness was calculated as (1-OR) × 100 %. RESULTS: There were 160 infant pertussis cases and 302 matched controls included in this Tdap5-specific study. Tdap5 effectiveness in preventing pertussis in infants whose pregnant parents were vaccinated between 27 and 36 weeks' gestation was 92.5 % (95 % CI, 38.5 %-99.1 %). Effectiveness of Tdap5 against pertussis-related hospitalization in infants whose pregnant parents were vaccinated between 27 and 36 weeks' gestation could not be calculated due to lack of discordance among matched cases and controls. Vaccination of the parents after pregnancy or less than 14 days before delivery did not protect infants from pertussis. CONCLUSIONS: Tdap5 vaccination in pregnancy between 27 and 36 weeks' gestation is highly effective at protecting young infants from pertussis. STUDY REGISTRATION: ClinicalTrials.gov, NCT05040802.

Hepatitis B surface antigen prevalence and the rates of mother-to-child transmission of hepatitis B virus after the introduction of infant vaccination programs in South East Asia and Western Pacific regions: a systematic review.

OBJECTIVES: Infant vaccination against the hepatitis B virus began in the World Health Organization South East Asia Region and the Western Pacific Region between 1983 and 2016. This systematic review examined the seroprevalence of hepatitis B surface antigen (HBsAg) in children and the rate of mother-to-child transmission (MTCT) in these regions between 1990 and 2020. METHODS: MEDLINE and EMBASE were searched for articles published between January 1990 and September 2020, which reported seroprevalence of HBsAg in children aged 0-15 years and/or the rate of MTCT in the South East Asia Region and Western Pacific Region. A pragmatic review identified supporting information. This review was registered in the International Prospective Register of Systematic Reviews (#CRD42020211707). RESULTS: Of 115 included studies, 77 (24 countries) reported HBsAg prevalence, and 38 (nine countries) reported MTCT. The seroprevalence of HBsAg ranged between 0.0% and 27.4%, with a decreasing trend over time in each country. MTCT rates were 0.0-5.2% in infants of mothers who are hepatitis B e antigen-negative and 2.7-53.0% in infants of mothers who are hepatitis B e antigen-positive. CONCLUSION: After the introduction of infant hepatitis B virus vaccination programs, the countries in South East Asia Region and Western Pacific Region observed a reduction in HBsAg seroprevalence in children. Nevertheless, the risk of MTCT persists, emphasizing the importance of antenatal screening to identify high-risk pregnancies.

What is the true burden of diphtheria, tetanus, pertussis and poliovirus in children aged 3-18 years in Asia? A systematic literature review.

OBJECTIVES: In recent years, outbreaks and a rising incidence of diphtheria, tetanus, and pertussis have occurred in Asia, particularly in older children. METHODS: A systematic search of MEDLINE and Embase was conducted from January 2000 to October 2020 to identify the epidemiology of diphtheria, tetanus, pertussis, and poliomyelitis in children and adolescents (aged 3-18 years) in Asia. The results were then related to vaccination schedules, booster coverage rates, pertussis source of infection, and booster immunogenicity, as identified by a pragmatic review. The International Prospective Register of Systematic Reviews (PROSPERO) registration: #CRD42020222445. RESULTS: A total of 35 studies were included in this review. Limited data were reported on the epidemiology of diphtheria, tetanus, pertussis, and poliomyelitis. Data from studies reporting the incidence of diphtheria and pertussis exemplify the shift in epidemiology to older children/adolescents. Seroprevalence data suggest that immunity to pertussis and diphtheria is below the level of herd immunity in several Asian countries in this population. CONCLUSION: The true burden of diphtheria, pertussis, and tetanus in children aged 3-18 years in Asia is unknown because of weak or absent nationwide surveillance systems. The available evidence highlights the inadequacies in immunity, either by gaps in a recommendation or suboptimal booster coverage, supporting the public health need for booster vaccinations in this population.

Duration of protection against Bordetella pertussis infection elicited by whole-cell and acellular vaccine priming in Polish children and adolescents.

BACKGROUND: In the context of reported resurgence of pertussis in the last decade, researchers hypothesized that acellular (aP) pertussis vaccines elicit a shorter-lived protection compared to whole-cell (wP) pertussis vaccines. However, in the studies seeking to demonstrate this hypothesis, exposure to each vaccine type was not concurrent, and contradictory epidemiologic modeling questioned its validity. The context of pertussis vaccination history in Poland, with both vaccine types used concurrently in comparable proportions, provided an opportunity to investigate this hypothesis. We sought to compare waning of protection by primary series vaccine type by measuring anti-pertussis toxin antibody concentrations as proxy for recent infection. MATERIALS AND METHODS: Serological samples from 2,745 children and adolescents aged ≥5 years and <16 years and with completed 5-dose pertussis vaccination series were tested by ELISA for pertussis toxin (PT) antibodies. Participants were stratified by type of priming vaccine (wP or aP). Vaccination timeliness and priming-specific trends in anti-PT antibody levels by time since last vaccine dose were analyzed. RESULTS: A total of 1,161 (42.5%) children received wP vaccines, and 1,314 (48.1%) received aP vaccines for their primary series and toddler booster. Overall, 53.57% of the subjects received doses 2-4 in a timely manner, while only 41.52% received all 5 doses at the recommended intervals. Using GMCs or seropositivity measures, both priming groups showed a re-increase in anti-PT antibody levels signing infection in recent years from 8 years after the school-entry booster onward. Comparisons did not show any significant differences between the two groups in the timing or intensity of this re-increase. CONCLUSION: Our results clearly confirm that vaccine-elicited immunity against pertussis wanes among adolescents even after a complete infant, toddler and school-entry vaccination series. The timing and intensity of the waning of protection appear similar with whole-cell as with acellular pertussis vaccines.

Impact of COVID-19 on routine immunisation in South-East Asia and Western Pacific: Disruptions and solutions.

BACKGROUND: Data on COVID-19-induced disruption to routine vaccinations in the South-East Asia and Western Pacific regions (SEAR/WPR) have been sparse. This study aimed to quantify the impact of COVID-19 on routine vaccinations by country, antigen, and sector (public or private), up to 1 June 2020, and to identify the reasons for disruption and possible solutions. METHODS: Sanofi Pasteur teams from 19 countries in SEAR/WPR completed a structured questionnaire reporting on COVID-19 disruptions for 13-19 routinely delivered antigens per country, based on sales data, government reports, and regular physician interactions. Data were analysed descriptively, disruption causes ranked, and solutions evaluated using a modified public health best practices framework. FINDINGS: 95% (18/19) of countries reported vaccination disruption. When stratified by country, a median of 91% (interquartile range 77-94) of antigens were impacted. Infancy and school-entry age vaccinations were most impacted. Both public and private sector healthcare providers experienced disruptions. Vaccination rates had not recovered for 39% of impacted antigens by 1 June 2020. Fear of infection, movement/travel restrictions, and limited healthcare access were the highest-ranked reasons for disruption. Highest-scoring solutions were separating vaccination groups from unwell patients, non-traditional vaccination venues, virtual engagement, and social media campaigns. Many of these solutions were under-utilised. INTERPRETATION: COVID-19-induced disruption of routine vaccination was more widespread than previously reported. Adaptable solutions were identified which could be implemented in SEAR/WPR and elsewhere. Governments and private providers need to act urgently to improve coverage rates and plan for future waves of the pandemic, to avoid a resurgence of vaccine-preventable diseases. FUNDING: Sanofi Pasteur.

Vaccine-Related Errors in Reconstitution in South Korea: A National Physicians' and Nurses' Survey.

Vaccine-related errors (VREs) result from mistakes in vaccine preparation, handling, storage, or administration. We aimed to assess physicians' and nurses' experiences of VREs in South Korea, focusing on reconstitution issues, and to understand the barriers to and facilitators of preventing them. This was a cross-sectional study using an internet-based survey to examine experiences of reconstitution-related errors, and experience or preference with regard to ready-to-use vaccines (RTU) by physicians and nurses. A total of 700 participants, including 250 physicians and 450 nurses, responded to the questionnaire. In total, 76.4% and 41.5% of the physicians and nurses, respectively, reported an error related to reconstituted vaccines. All errors had been reported as experienced by between 4.9% and 52.0% of physicians or nurses. The errors were reported to occur in more than one in 100 vaccinations for inadequate shaking of vaccines by 28.0% of physicians and 6.9% of nurses, incomplete aspiration of reconstitution vials by 28.0% of physicians and 6.4% of nurses, and spillage or leakage during reconstitution by 20.8% of physicians and 6.9% of nurses. A total of 94.8% of physicians had experience with RTU vaccines, and all preferred RTU formulations. In conclusion, this study highlights the high frequency and types of reconstitution-related errors in South Korea. RTU vaccines could help reduce the time needed for preparation and reduce the risk of errors in South Korea.

Altering the motility of Trypanosoma cruzi with rabbit polyclonal anti-peptide antibodies reduces infection to susceptible mammalian cells.

Trypanosoma cruzi's trypomastigotes are highly active and their incessant motility seems to be important for mammalian host cell infection. The kinetoplastid membrane protein-11 (KMP-11) is a protein expressed in all parasite stages, which induces a cellular and humoral immune response in the infected host, and is hypothesized to participate in the parasite's motility. An N-terminal peptide from KMP-11, termed K1 or TcTLE, induced polyclonal antibodies that inhibit parasitic invasion of Vero cells. The goal of this study was to evaluate the motility and infectivity of T. cruzi when exposed to polyclonal anti-TcTLE antibodies. Rabbits were immunized with TcTLE peptide along with FIS peptide as an immunomodulator. ELISA assay results showed that post-immunization sera contained high titers of polyclonal anti-TcTLE antibodies, which were also reactive against the native KMP-11 protein and live parasites as detected by immunofluorescence and flow cytometry assays. Trypomastigotes of T. cruzi were incubated with pre- or post-immunization sera, and infectivity to human astrocytes was assessed by Giemsa staining/light microscope and flow cytometry using carboxyfluorescein diacetate succinimidyl ester (CFSE) labeled parasites. T. cruzi infection in astrocytes decreased approximately by 30% upon incubation with post-immunization sera compared with pre-immunization sera. Furthermore, trypomastigotes were recorded by video microscopy and the parasite's flagellar speed was calculated by tracking the flagella. Trypomastigotes exposed to post-immunization sera had qualitative alterations in motility and significantly slower flagella (45.5 µm/s), compared with those exposed to pre-immunization sera (69.2 µm/s). In summary, polyclonal anti-TcTLE serum significantly reduced the parasite's flagellar speed and cell infectivity. These findings support that KMP-11 could be important for parasite motility, and that by targeting its N-terminal peptide infectivity can be reduced.