Effectiveness of 10-valent pneumococcal conjugate vaccine estimated with three parallel study designs among vaccine-eligible children in Finland

Overview of childhood vaccination coverage in Brazil and the impact of the COVID-19 pandemic: Is our children's health at risk? A review of pre-COVID-19 periods and during the COVID-19 pandemic

Introduction

The coronavirus disease (COVID)-19 has had a great impact on several aspects related to the population's health, including the vaccination adherence rate. This study describes how childhood vaccination coverage (CVC) in Brazil was affected by the pandemic in the period from 2020 to 2022 and explores the relationship between this data and the Human Development Index (HDI), and the number of votes received in the government with a right-wing political ideology.

Methods

An ecological analysis of CVC was carried out including 12 vaccines. The HDI was evaluated considering the HDI-General, HDI-Income, HDI-Longevity, and HDI-Education. The percentage of valid votes received by the former president (right-wing political ideology) was also obtained. Spearman correlation tests were applied to compare markers.

Results

During the period analyzed, it was observed a linear growth trend in CVC between 2015 and 2018 regarding all vaccines. However, from 2018 onwards, after the presidential elections in Brazil, the CVC reduced significantly, showing an even more pronounced decrease with the start of the COVID-19 pandemic. This reduction in CVC observed for some vaccines was related to the higher percentage of votes for the government with a right-wing political ideology, especially in relation to the BCG (bacillus Calmette and Guerin) and pentavalent (protecting against diphtheria, tetanus, pertussis, hepatitis B, and Haemophilus influenzae type b bacteria) vaccines. In addition, when analyzing the HDI, it was observed that the lowest values of this indicator were associated with a more expressive reduction in CVC, mainly related to yellow fever, pentavalent, 10-valent pneumococcal conjugate, Human rotavirus, and triple viral (protecting against measles, mumps, and rubella - MMR) vaccines.

Conclusion

Although Brazil has a successful and exemplary record in combating several diseases, mainly due to the high rate of CVC, the continuous reduction in this coverage must be thoroughly evaluated by health managers.

Effectiveness of 10 and 13-valent pneumococcal conjugate vaccines against invasive pneumococcal disease in European children: SpIDnet observational multicentre study

BACKGROUND

Pneumococcal conjugate vaccines covering 10 (PCV10) and 13 (PCV13) serotypes have been introduced in the infant immunization schedule of most European countries in 2010-11. To provide additional real-life data, we measured the effectiveness of PCV10 and PCV13 against invasive pneumococcal disease (IPD) in children of 12 European sites (SpIDnet).

METHODS

We compared the vaccination status of PCV10 and PCV13 serotype IPD (cases) to that of nonPCV13 serotype IPD (controls) reported in 2012-2018. We calculated pooled effectiveness as (1-vaccination odds ratio)*100, and measured effectiveness over time since booster dose.

RESULTS

The PCV13 and PCV10 studies included 2522 IPD cases from ten sites and 486 cases from four sites, respectively. The effectiveness of ≥ 1 PCV13 dose was 84.2% (95 %CI: 79.0-88.1) against PCV13 serotypes (n = 2353) and decreased from 93.1% (87.8-96.1) < 12 months to 85.1% (72.0-92.1) ≥ 24 months after booster dose. PCV13 effectiveness of ≥ 1 dose was 84.7% (55.7-94.7) against fatal PCV13 IPD, 64.5% (43.7-77.6), 83.2% (73.7-89.3) and 85.1% (67.6-93.1) against top serotypes 3, 19A and 1, respectively, and 85.4% (62.3-94.4) against 6C. Serotype 3 and 19A effectiveness declined more rapidly. PCV10 effectiveness of ≥ 1 dose was 84.8% (69.4-92.5) against PCV10 serotypes (n = 370), 27.2% (-187.6 to 81.6) and 85.3% (35.2-96.7) against top serotypes 1 and 7F, 32.5% (-28.3 to 64.5) and -14.4% (-526.5 to 79.1) against vaccine-related serotypes 19A and 6C, respectively.

CONCLUSIONS

PCV10 and PCV13 provide similar protection against IPD due to the respective vaccine serotype groups but serotype-specific effectiveness varies by serotype and vaccine. PCV13 provided individual protection against serotype 3 and vaccine-related serotype 6C IPD. PCV10 effectiveness was not significant against vaccine-related serotypes 19A and 6C. PCV13 effectiveness declined with time after booster vaccination. This multinational study enabled measuring serotype-specific vaccine effectiveness with a precision rarely possible at the national level. Such large networks are crucial for the post-licensure evaluation of vaccines.

Effectiveness of 7-Valent Pneumococcal Conjugate Vaccine Against Invasive Pneumococcal Disease in Medically At-Risk Children in Australia: A Record Linkage Study

BACKGROUND

Children with chronic medical conditions are at higher risk of invasive pneumococcal disease (IPD), but little is known about the effectiveness of the primary course of pneumococcal conjugate vaccine (PCV) in these children.

METHODS

A cohort born in 2001-2004 from two Australian states and identified as medically at-risk (MAR) of IPD either using ICD-coded hospitalizations (with conditions of interest identified by 6 months of age) or linked perinatal data (for prematurity) were followed to age 5 years for notified IPD by serotype. We categorized fully vaccinated children as either receiving PCV dose 3 by <12 months of age or ≥1 PCV dose at ≥12 months of age. Cox proportional hazard modeling was used to estimate hazard ratios (HRs), adjusted for confounders, and vaccine effectiveness (VE) was estimated as (1-HR) × 100.

RESULTS

A total of 9220 children with MAR conditions had 53 episodes of IPD (43 vaccine-type); 4457 (48.3%) were unvaccinated and 4246 (46.1%) were fully vaccinated, with 1371 (32.3%) receiving dose 3 by 12 months and 2875 (67.7%) having ≥1 dose at ≥12 months. Estimated VE in fully vaccinated children was 85.9% (95% CI: 33.9-97.0) against vaccine-type IPD and 71.5% (95% CI: 26.6-88.9) against all-cause IPD.

CONCLUSION

This is the first population-based study evaluating the effectiveness of PCV in children with MAR conditions using record linkage. Our study provides evidence that the VE for vaccine-type and all-cause IPD in MAR children in Australia is high and not statistically different from previously reported estimates for the general population. This method can be replicated in other countries to evaluate VE in MAR children.

Impact and effectiveness of a conjugate vaccine against invasive pneumococcal disease in Finland - a modelling approach

The evaluation of the public health impact of a vaccination program is essential in monitoring its policy relevance. Vaccine impact (VI) is usually assessed in a before-after design, in which data on disease burden without vaccination program is required from a historical reference period. It takes into account the indirect effects and therefore aims to describe the public health performance of the vaccination program in the population. Vaccine effectiveness (VE), measured in parallel settings, quantifies the benefit for an individual of being vaccinated but does not address the indirect effects of a vaccination program. The motivation of this paper is to gain insight into patterns of how VI and VE have manifested under large-scale use of a ten-valent pneumococcal conjugate vaccine in Finnish children. We construct a simple pseudo-dynamic model that mimics typical post-vaccination trends in the incidences of pneumococcal carriage and invasive disease in children when the proportion of vaccine-type carriage decreases. In the context of the model, we define the parameters of interest for VI and VE and explore how their expected values evolve over time. For comparison, we demonstrate the application of VI and VE estimation by using register data.

Exploring the evidence behind the comparable impact of the pneumococcal conjugate vaccines PHiD-CV and PCV13 on overall pneumococcal disease

The worldwide implementation of pneumococcal conjugate vaccines (PCVs) in children has reduced the overall pneumococcal disease burden. Two PCVs are widely available for infant vaccination: the pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) and the 13-valent PCV (PCV13). While these PCVs differ in serotype composition (PCV13 includes polysaccharides of serotypes 3, 6A and 19A; PHiD-CV does not), their impact on the overall pneumococcal disease burden in children is comparable. This commentary summarizes the evidence of comparability between PHiD-CV and PCV13 and explores why differences in serotype composition may not necessarily translate into a differential clinical impact. Both vaccines confer similarly high protection against disease caused by vaccine serotypes and lead to a partial replacement by non-vaccine serotypes. PHiD-CV does not protect against serotype 3 disease (not included in the vaccine) and PCV13’s effect on this serotype has been inconsistent. PHiD-CV provides some cross-protection against disease caused by vaccine-related serotype 19A but neither vaccine has fully controlled 19A disease. While protection against 19A is higher for PCV13 than PHiD-CV, replacement by non-PCV13 serotypes in settings with a PCV13 program appears to compensate for this difference. This results in a similar residual overall disease burden with both vaccines.

What is the context?

The pneumococcus bacterium can cause infections of the meninges, blood, lung, middle ear and sinuses.

Two vaccins, Synflorix (GSK) and Prevnar 13 (Pfizer Inc.), are widely used to protect young children against these infections.

The vaccines’ compositions differ: Synflorix includes antigens from 10 pneumococcus strains (or “serotypes”) and Prevnar 13 from 13 serotypes.

However, both have a similar effect on the total pneumococcal disease burden in children.

What does this commentary highlight?

This commentary summarizes the evidence beihnd the two vaccines’ comparable impact on pneumococcal disase.

It also looks at why the vaccines have a similar effect on the total pneumococcal disease burden despite their different compositions.

What is the impact on current thinking?

Given that Synflorix and Prevnar 13 have a comparable impact on pneumococcal disease, a country’s choice between the two vaccines will depend on vaccine supply, cost, logistical factors (e.g., transport, storage, training requirements of health workers) and the local pneumococcal epidemiology.

Impact and effectiveness of the 10-valent pneumococcal conjugate vaccine on invasive pneumococcal disease among children under 5 years of age in the Netherlands

BACKGROUND

In 2011, the 7-valent pneumococcal conjugate vaccine (PCV7) was replaced by the 10-valent vaccine (PCV10) in the Netherlands. We report on impact and effectiveness against invasive pneumococcal disease (IPD) in children aged under 5 years by switching from PCV7 to PCV10.

METHOD

We included IPD cases between 2004 and 2019 in children aged < 5 years reported via the national surveillance system. To assess the impact of the PCV10 vaccination program we compared IPD incidence 6-8 years after PCV10 introduction (2017-2019) to the two years just before the switch to PCV10 (2009-2011). We estimated vaccine effectiveness (VE) using the indirect cohort method, comparing vaccination status (at least two vaccine doses) in IPD-cases caused by PCV10 serotypes (cases) to non-PCV10 IPD cases (controls), in children eligible for PCV10.

RESULTS

The overall incidence decreased from 8.7 (n = 162) in 2009-2011 to 7.3 per 100.000 (n = 127) in 2017-2019 (Incidence rate ratio (IRR) 0.83, 95%CI: 0.66; 1.05). IPD caused by the additional serotypes included in PCV10 declined by 93% (IRR 0.07, 95%CI: 0.02; 0.23). Incidence of non-PCV10 IPD showed a non-significant increase (IRR 1.25, 95%CI: 0.96; 1.63). Among 231 IPD-cases eligible for PCV10, the overall VE was 91% (95%CI: 67; 97) and did not differ by sex or age at diagnosis. Effectiveness against non-PCV10 serotype 19A IPD was non-significant with an estimate of 28% (95%CI:-179; 81).

CONCLUSION

PCV10 is highly effective in protecting against IPD in Dutch children under 5 years with limited serotype replacement after switching from PCV7 to PCV10. We found no evidence for significant cross-protection of PCV10 against 19A serotype IPD.

Dynamic changes in paediatric invasive pneumococcal disease after sequential switches of conjugate vaccine in Belgium: a national retrospective observational study

BACKGROUND

Ten-valent and 13-valent pneumococcal conjugate vaccines (PCVs) have shown important benefits by decreasing invasive pneumococcal disease caused by vaccine serotypes. Belgium had an uncommon situation with sequential use of PCV7, PCV13, and PCV10 in the childhood vaccination programmes between 2007 and 2018. We aimed to analyse the changes in incidence of invasive pneumococcal disease and serotype distribution in children throughout this period.

METHODS

Streptococcus pneumoniae isolates were obtained from patients with invasive pneumococcal disease in Belgium between 2007 and 2018 by the national laboratory-based surveillance. Paediatric invasive pneumococcal disease incidence, serotype distribution, and antimicrobial susceptibility were analysed in periods during which PCV7 (2009-10), PCV13 (2013-14), both PCV13 and PCV10 (2015-16), and PCV10 (2017-18) were used. Incidence rates and trends were compared. Vaccination status was collected. For a subset of serotype 19A isolates, multilocus sequence type was identified.

FINDINGS

After a decrease in PCV7 serotype invasive pneumococcal disease was observed during the PCV7 period, total paediatric invasive pneumococcal disease incidence significantly declined during the PCV13 period (-2·6% monthly, p<0·0001). During the PCV13-PCV10 period (2015-16), the lowest mean in paediatric invasive pneumococcal disease incidence was achieved, but the incidence increased again during the PCV10 period (2017-18), especially in children younger than 2 years (+1·7% monthly; p=0·028). This increase was mainly due to a significant rise in serotype 19A invasive pneumococcal disease incidence in the PCV10 period compared with the PCV13 period (p<0·0001), making serotype 19A the predominant serotype in paediatric invasive pneumococcal disease in the PCV10 period. Genetic diversity within the 2017-18 serotype 19A collection was seen, with two predominant clones, ST416 and ST994, that were infrequently observed before PCV10 introduction. In 2018, among children younger than 5 years with invasive pneumococcal disease who were correctly vaccinated, 37% (37 of 100) had PCV13 serotype invasive pneumococcal disease, all caused by serotype 19A and serotype 3.

INTERPRETATION

After a significant decrease during the PCV13 period, paediatric invasive pneumococcal disease incidence increased again during the PCV10 period. This observation mainly resulted from a significant increase of serotype 19A cases. During the PCV10 period, dominant serotype 19A clones differed from those detected during previous vaccine periods. Whether changes in epidemiology resulted from the vaccine switch or also from natural evolution remains to be further elucidated.

FUNDING

The Belgian National Reference is funded by the Belgian National Institute for Health and Disability Insurance and the whole genome sequencing by an investigator-initiated research grant from Pfizer.