Association between anti-capsular IgG levels at birth and risk of invasive group B streptococcus disease in Finnish newborns: a retrospective case-control study

BACKGROUND

Group B streptococcus is a major cause of neonatal disease. Natural history studies have linked maternally transferred anti-group B streptococcus capsular polysaccharide antibodies with protection against infant group B streptococcus disease. Previous studies of capsular polysaccharide antibody concentration in European populations have used maternal (not infant) sera and a non-standardised assay. This study aimed to evaluate anti-capsular polysaccharide IgG concentrations associated with protection against invasive group B streptococcus disease in Finnish infants.

METHODS

In this retrospective case-control study, we used cord sera from the Finnish DIPP study repository, which was obtained between Jan 1, 1995, and Dec 31, 2017. We included infants aged 6 months or younger with group B streptococcus infection (cases) and healthy infants (controls). We enrolled infants with invasive neonatal group B streptococcus (55 cases) and matched controls (229 controls) aged 6 months or younger after identification from Finnish health registers. We measured anti-capsular polysaccharide IgG (serotypes Ia-V) concentration using a standardised immunoassay and we estimated its relationship to disease risk using a Bayesian model. We used the derived risk-concentration curve to predict potential efficacy of six-valent group B streptococcus capsular polysaccharide vaccine (GBS6) based on previously reported immunogenicity data.

FINDINGS

Most (32 [58%] of 55 cases) group B streptococcus cases were due to serotype III and anti-serotype III streptococcus capsular IgG concentrations were higher in serotype III-matched controls than in cases (p<0·001). 0·120-0·266 μg/mL serotype III-specific IgG was estimated to confer 75-90% risk reduction against serotype III disease. A universal risk-concentration curve, aggregating results across all six serotypes, yielded similar results. Application of this curve to GBS6 immunogenicity data predicted maternal immunisation to be more than 80% efficacious for prevention of infant group B streptococcus disease.

INTERPRETATION

Higher neonatal anti-capsular polysaccharide serum IgG concentration at birth correlated with reduced risk of infant group B streptococcus disease in Finland. Based on these results, a maternal group B streptococcus capsular conjugate vaccine currently in development is predicted to be efficacious.

FUNDING

Pfizer.

High-Dose Quadrivalent Influenza Vaccine for Prevention of Cardiovascular and Respiratory Hospitalizations in Older Adults

BACKGROUND

We assessed the relative vaccine effectiveness (rVE) of high-dose quadrivalent influenza vaccine (QIV-HD) versus standard-dose quadrivalent influenza vaccine (QIV-SD) in preventing respiratory or cardiovascular hospitalizations in older adults.

METHODS

FinFluHD was a phase 3b/4 modified double-blind, randomized pragmatic trial. Enrolment of 121,000 adults ≥65 years was planned over three influenza seasons (October to December 2019-2021). Participants received a single injection of QIV-HD or QIV-SD. The primary endpoint was first occurrence of an unscheduled acute respiratory or cardiovascular hospitalization (ICD-10 primary discharge J/I codes), from ≥14 days post-vaccination until May 31. The study was terminated after one season due to COVID-19; follow-up data for 2019-2020 are presented.

RESULTS

33,093 participants were vaccinated (QIV-HD, n = 16,549; QIV-SD, n = 16,544); 529 respiratory or cardiovascular hospitalizations (QIV-HD, n = 257; QIV-SD, n = 272) were recorded. The rVE of QIV-HD versus QIV-SD to prevent respiratory/cardiovascular hospitalizations was 5.5% (95% CI, -12.4 to 20.7). When prevention of respiratory and cardiovascular hospitalizations were considered separately, rVE estimates of QIV-HD versus QIV-SD were 5.4% (95% CI, -28.0 to 30.1) and 7.1% (95% CI, -15.0 to 25.0), respectively. Serious adverse reactions were <0.01% in both groups.

CONCLUSIONS

Despite insufficient statistical power due to the impact of COVID-19, rVE point estimates demonstrated a trend toward a benefit of QIV-HD over QIV-SD. QIV-HD was associated with lower respiratory or cardiovascular hospitalization rates than QIV-SD, with a comparable safety profile. Adequately powered studies conducted over multiple influenza seasons are needed to determine statistical significance of QIV-HD compared with QIV-SD against preventing respiratory and cardiovascular hospitalizations.

TRIAL REGISTRATION

ClinicalTrials.gov number: NCT04137887.

Underreporting of SARS-CoV-2 infections during the first wave of the 2020 COVID-19 epidemic in Finland-Bayesian inference based on a series of serological surveys

In Finland, the first wave of the COVID-19 epidemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) took place from March to June 2020, with the majority of COVID-19 cases diagnosed in the Helsinki-Uusimaa region. The magnitude and trend in the incidence of COVID-19 is one way to monitor the course of the epidemic. The diagnosed COVID-19 cases are a subset of the infections and therefore the COVID-19 incidence underestimates the SARS-CoV-2 incidence. The likelihood that an individual with SARS-CoV-2 infection is diagnosed with COVID-19 depends on the clinical manifestation as well as the infection testing policy and capacity. These factors may fluctuate over time and the underreporting of infections changes accordingly. Quantifying the extent of underreporting allows the assessment of the true incidence of infection. To obtain information on the incidence of SARS-CoV-2 infection in Finland, a series of serological surveys was initiated in April 2020. We develop a Bayesian inference approach and apply it to data from the serological surveys, registered COVID-19 cases, and external data on antibody development, to estimate the time-dependent underreporting of SARS-Cov-2 infections during the first wave of the COVID-19 epidemic in Finland. During the entire first wave, there were 1 to 5 (95% probability) SARS-CoV-2 infections for every COVID-19 case. The underreporting was highest before April when there were 4 to 17 (95% probability) infections for every COVID-19 case. It is likely that between 0.5%-1.0% (50% probability) and no more than 1.5% (95% probability) of the adult population in the Helsinki-Uusimaa region were infected with SARS-CoV-2 by the beginning of July 2020.

Changes in SARS-CoV-2 seroprevalence and population immunity in Finland, 2020-2022

Studying the prevalence of SARS-CoV-2 specific antibodies (seroprevalence) allows for assessing the impact of epidemic containment measures and vaccinations and estimating the number of infections regardless of viral testing. We assessed antibody-mediated immunity to SARS-CoV-2 induced by infections and vaccinations from April 2020 to December 2022 in Finland by measuring serum IgG to SARS-CoV-2 nucleoprotein (N-IgG) and spike glycoprotein from randomly selected 18-85-year-old subjects (n = 9794). N-IgG seroprevalence remained at <7% until the last quartile (Q) of 2021. After the emergence of the omicron variant, N-IgG seroprevalence increased rapidly and was 31% in Q1/2022 and 54% in Q4/2022. Seroprevalence was highest in the youngest age groups from Q2/2022 onwards. We did not observe regional differences in seroprevalence in 2022. We estimated that 51% of the Finnish 18-85-year-old population had antibody-mediated hybrid immunity induced by a combination of vaccinations and infections by the end of 2022. In conclusion, major shifts in the COVID-19 pandemic and resulting population immunity could be observed by serological testing.

Incidence of sinus thrombosis with thrombocytopenia-A nation-wide register study

Safe vaccination is essential for mitigation of the COVID-19 pandemic. Two adenoviral vector vaccines, ChAdOx1 nCov-19 (AstraZeneca) and Ad26.COV2.S (Johnson&Johnson/Janssen) have shown to be effective and they are distributed globally, but reports on serious cerebral venous sinus thrombosis (CVST) associated with thrombocytopenia, have emerged. Our objective was to evaluate the background incidence of CVST with thrombocytopenia and to compare it to incidences following COVID-19 vaccines. We conducted a register-based nation-wide cohort study in Finland, including all 5.5 million individuals alive in Finland, 1 Jan 2020. COVID-19 vaccinations registered in the National Vaccination Register served as the exposure. We detected CVST admissions or hospital visits recorded in the hospital discharge register from Jan 1, 2020 through April 2, 2021. We confirmed the diagnosis of CVST and thrombocytopenia (platelet count <150,000 per cubic millimeter) using radiology reports and laboratory data. By Poisson regression, we compared the baseline incidences to the risks within four weeks after COVID-19 vaccinations. Out of the 167 CVST episodes identified in the registers, 117 were confirmed as CVST, 18 of which coincided with thrombocytopenia (baseline incidence 0.18 per 28 days per million persons). We found 2 episodes of CVST with thrombocytopenia within 28 days of the first ChAdOx1 nCov-19 vaccination (among 200,397 vaccinated, aged 16 or above). No cases were found following the first mRNA vaccine dose among 782,604 vaccinated. The background incidence of CVST combined with thrombocytopenia was minuscule compared to the incidence during the weeks following the ChAdOx1 nCov-19 vaccination. Accurate estimation of the baseline incidence is essential in the critical appraisal of the benefit-risk of any vaccination program.

Cohort Profile: Childhood morbidity and potential non-specific effects of the childhood vaccination programmes in the Nordic countries (NONSEnse): register-based cohort of children born 1990-2017/2018

PURPOSE

The aim of the NONSEnse project is to investigate the non-specific effects of vaccines and immunisation programmes on the overall health of children by using information from the extensive nationwide registers on health and sociodemographic factors in Denmark, Finland, Norway and Sweden.

PARTICIPANTS

The cohort covers 9 072 420 children aged 0-17 years, born 1990-2017/2018 and living in Denmark, Finland, Norway or Sweden. All countries use a unique identification number for its permanent residents, which makes it possible to link individual-level information from different registers.

FINDINGS TO DATE

Data collection and harmonisation according to a common data model was completed in March 2022. As a prerequisite for comparing the effects of childhood vaccinations on the overall health of children across the Nordic countries, we have identified indicators measuring similar levels of infectious disease morbidity across these settings. So far, studies pertaining to non-specific effects of vaccines are limited to investigations that could be undertaken using aggregated data sets that were available before the NONSEnse cohort with individual-level information was completely set up.

FUTURE PLANS

We are currently performing several studies of the effects on non-targeted infectious disease morbidity across the countries following vaccination against measles, mumps, rubella, diphtheria, tetanus, pertussis, human papillomavirus, rotavirus and influenza. Multiple studies are planned within the next years using different study designs to facilitate triangulation of results and enhance causal inference.

REGISTRATION

No clinical trials will be conducted within the NONSEnse project.

A retrospective nationwide register-based study to evaluate the non-specific effects of first MMR vaccination among children in Finland

BACKGROUND

According to earlier studies, live vaccines like measles-mumps-rubella (MMR) vaccine could reduce also other infections than only the infections they are targeted against. This non-specific effect has been seen especially in studies in low-income countries and results from high-income countries have not been unambiguous. In 2011 Finland changed the recommended schedule for the first MMR vaccination from 18 months to 12 months of age. This change created a natural experiment for evaluating the potential non-specific effects.

METHODS

This is a retrospective nationwide register-based cohort study of Finnish children born between 2008 and 2012. Children were divided into two cohorts by age at MMR vaccination: children administered early MMR vaccination (11 through 12 months of age) and late MMR vaccination (18 through 19 months of age). Morbidity was evaluated during the main follow-up period (from 13 to 17 months of age) and before any MMR vaccination (3 to 10 months) and after all were vaccinated with MMR (20 to 35 months) as control follow-up periods. We analyzed all infections and did additional analyzes for urinary tract infections (UTI) and bronchitis. Injuries were analyzed as a control outcome.

RESULTS

Early MMR vaccinated children (N = 79949) had fewer infections compared to late MMR vaccinated (N = 60965) during the main follow-up period. The incidence rate ratio (IRR) was 0.84 (95 % confidence interval (95 % CI) 0.81-0.87). However, similar differences were also observed during the control follow-up periods. MMR vaccinated children had less UTI in the main follow-up period (IRR 0.73, 0.60-0.89) but not in the control follow-up periods. When stratified by sex, the difference was observed among girls but not in boys.

CONCLUSION

No clear evidence was found for non-specific effects in infectious diseases morbidity. However, there could be a nonspecific effect on UTI. Confirmation is needed from other studies, especially from high-income countries.

Pneumococcal vaccine schedules (PVS) study: a cluster-randomised, non-inferiority trial of an alternative versus standard schedule for pneumococcal conjugate vaccination-statistical analysis plan

RATIONALE

The effectiveness of universal immunisation with pneumococcal conjugate vaccine (PCV) has been evident in many countries. However, the global impact of PCV is limited by its cost, which has prevented its introduction in several countries. Reducing the cost of PCV programmes may facilitate vaccine introduction in some countries and improve the sustainability of PCV in EPIs in low-income countries when they transition away from subsidised vaccine supply.

METHODS AND DESIGN

PVS is a real-world field trial of an alternative schedule of one dose of PCV scheduled at age 6 weeks with a booster dose at age 9 months (i.e. the alternative '1+1' schedule) compared to the standard schedule of three primary doses scheduled at 6, 10, and 14 weeks of age (i.e. the standard '3+0' schedule). Delivery of the interventions began in late 2019 in 68 geographic clusters and will continue for 4 years. The primary endpoint is the prevalence of nasopharyngeal vaccine-type pneumococcal carriage in children aged 2-260 weeks with clinical pneumonia in year 4. Secondary endpoints are the prevalence of vaccine-type pneumococcal carriage among all ages in year 4 and the incidence of radiological pneumonia in children enrolled to receive the interventions. Additional disease and carriage endpoints are included.

PURPOSE

This statistical analysis plan (SAP) describes the cohorts and populations, and follow-up criteria, to be used in different analyses. The SAP defines the endpoints and describes how adherence to the interventions will be presented. We describe how analyses will account for the effect of clustering and stratified randomisation. The SAP defines the approach to non-inferiority and other analyses. Defining the SAP early in the trial will avoid bias in analyses that may arise from prior knowledge of trial findings.

Strong Neutralizing Antibody Responses to SARS-CoV-2 Variants Following a Single Vaccine Dose in Subjects With Previous SARS-CoV-2 Infection

BACKGROUND

Previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection primes the immune system; thus individuals who have recovered from infection have enhanced immune responses to subsequent vaccination (hybrid immunity). However, it remains unclear how well hybrid immunity induced by severe or mild infection can cross-neutralize emerging variants. We aimed to compare the strength and breadth of antibody responses in vaccinated recovered and uninfected subjects.

METHODS

We measured spike-specific immunoglobulin (Ig)G and neutralizing antibodies (NAbs) from vaccinated subjects including 320 with hybrid immunity and 20 without previous infection. From 29 subjects with a previous severe or mild infection, we also measured NAb responses against Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529/BA.1) variants following vaccination.

RESULTS

A single vaccine dose induced 2-fold higher anti-spike IgG concentrations and up to 4-fold higher neutralizing potency of antibodies in subjects with a previous infection compared with vaccinated subjects without a previous infection. Hybrid immunity was more enhanced after a severe than a mild infection, with sequentially decreasing NAb titers against Alpha, Beta, Delta, and Omicron variants. We found similar IgG concentrations in subjects with a previous infection after 1 or 2 vaccine doses.

CONCLUSIONS

Hybrid immunity induced strong IgG responses, particularly after severe infection. However, the NAb titers were low against heterologous variants, especially against Omicron.

High vaccine effectiveness against severe COVID-19 in the elderly in Finland before and after the emergence of Omicron

Background

The elderly are highly vulnerable to severe COVID-19. Waning immunity and emergence of Omicron have caused concerns about reduced effectiveness of COVID-19 vaccines. The objective was to estimate vaccine effectiveness (VE) against severe COVID-19 among the elderly.

Methods

This nationwide, register-based cohort analysis included all residents aged 70 years and over in Finland. The follow-up started on December 27, 2020, and ended on March 31, 2022. The outcomes of interest were COVID-19-related hospitalization and intensive care unit (ICU) admission timely associated with SARS-CoV-2 infection. VE was estimated as one minus the hazard ratio comparing the vaccinated and unvaccinated and taking into account time since vaccination. Omicron-specific VE was evaluated as the effectiveness observed since January 1, 2022.

Results

The cohort included 896,220 individuals. Comirnaty (BioNTech/Pfizer) VE against COVID-19-related hospitalization was 93% (95% CI 89–95%) and 85% (95% CI 82–87%) 14–90 and 91–180 days after the second dose; VE increased to 95% (95% CI 94–96%) 14–60 days after the third dose. VE of other homologous and heterologous three dose series was similar. Protection against severe COVID-19 requiring ICU treatment was even better. Since January 1, 2022, Comirnaty VE was 98% (95% CI 92–99%) and 92% (95% CI 87–95%) 14–90 and 91–180 days after the second and 98% (95% CI 95–99%) 14–60 days after the third dose.

Conclusions

VE against severe COVID-19 is high among the elderly. It waned slightly after two doses, but a third restored the protection. VE against severe COVID-19 remained high even after the emergence of Omicron.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07814-4.

Time and labour costs of preventive health care, including vaccinations, in Finnish child health clinics

In Finland all children are entitled to regular health check-up visits at child health clinics (CHC). During the visits public health nurses and physicians follow-up the growth and development of the child, evaluate the welfare of the family, give health counselling and vaccinate the children. The aim of this study was to measure the time used by the nurses and physicians for different tasks during the visits and evaluate the costs of preventive health care procedures. Special emphasis was on time and costs used for administering vaccinations. The study was conducted in four CHCs. Trained observers measured the time used for predefined tasks with a stopwatch application operating on a tablet computer. Labour costs of visits and vaccinations were evaluated by using the gross average salary costs of health care personnel. Time used for vaccine logistics and other administrative tasks was obtained by interviewing the nurses in charge of the vaccine logistics at each CHC. Altogether 325 CHC visits of children <13 months were followed. Public health nurse used for a visit in average 49 (range 12-101) minutes, and the corresponding labour costs were 17 (4-35) Euros. Vaccines were administered at 183 visits. Children got on average 2.4 (1-4) vaccine doses per visit. The observed time used for vaccinations was 10.2 (1.6-25) minutes and the costs 3.58 (0.57-8.62) Euros per visit. The observed time included guidance, preparation, administration, and documentation of vaccinations. Adding one dose into a visit increased the time spent on vaccination on average 2.8 minutes (0.99 Euros). The mean non-observed time used for vaccine logistics outside the visits was 3.4 minutes and cost 1.19 Euros per dose. Administering of the vaccines of the Finnish vaccination programme is relatively simple and inexpensive because Finnish children have regular scheduled visits to CHCs.

Trends in Antibiotic Use in Danish, Finnish, Norwegian and Swedish Children

Objective

To compare the use of antibiotics in children in four Northern European countries.

Methods

We conducted a register-based study based on individual-level prescription data from national prescription registers. We identified all redeemed outpatient prescriptions for systemic antibiotics in children aged 0–14 years from July 2006 to June 2017 in Denmark, Finland, Norway, and Sweden. We computed incidence rates and incidence rate ratios of treatment episodes with any antibiotic and different antibiotic classes.

Results

In 2016/2017, the rates of antibiotic treatment episodes per 1000 person-years in children aged 0–14 years were 429, 284, 219, and 184 in Finland, Denmark, Sweden, and Norway, respectively, and the rate ratios (95% confidence intervals) compared with Norway were 2.33 (2.33–2.34), 1.54 (1.54–1.55), and 1.19 (1.19–1.20) in Finland, Denmark, and Sweden, respectively. The rate of antibiotic treatment episodes declined over time in all countries. The relative reductions in 2016/2017 compared with 2006/2007 were 36% in Finland, 40% in Denmark, 49% in Sweden, and 29% in Norway. Treatment episodes peaked between age 12 and 18 months. The most used antibiotic class was beta-lactamase sensitive penicillins among all children in Norway and Sweden and among children above two years in Denmark, while penicillins with extended spectrum were most used in Finland and among the youngest children in Denmark.

Conclusion

In all countries, the use of antibiotics in children declined between 2006 and 2017. However, there were still considerable differences in antibiotic use between otherwise quite similar Nordic countries, with a more than 2-fold difference between the countries with the lowest and highest rates. Interventions to reduce the number of antibiotic treatment episodes in the countries with higher rates could reduce the total antibiotic use.

Effectiveness of trivalent influenza vaccines against hospitalizations due to laboratory-confirmed influenza a in the elderly: Comparison of test-negative design with register-based designs

INTRODUCTION

Measuring influenza vaccine effectiveness (IVE) seasonally is important and has been conducted utilizing several observational study designs. The active test-negative design has been most widely used and the validity of passive register-based studies has been debated. We aimed to explore the potential differences, advantages, and weaknesses of different study designs in estimating influenza vaccine effectiveness.

METHODS

We compared three study designs in estimating IVE against hospitalization in the elderly aged 65 years or more over three influenza seasons 2015/16, 2016/17 and 2017/18. Designs compared were active test-negative design (TND), register-based cohort design and register-based case-control design with different selection criteria for cases and controls.

RESULTS

Adjusted IVE estimates for the three consecutive seasons 2015-18 in active test-negative design were 82% (95% confidence interval 26, 96), 21% (-179, 77), 15% (-113, 66). For case-control design, estimates from different analyses ranged in 2015/16 from 47% (-16, 76) to 52% (-48, 84), in 2016/17 from 10% (-42, 43) to 29% (-20, 58), and in 2017/18 from -27% (-91, 15) to 1% (-40, 30). In the cohort design, the adjusted IVE estimates were 48% (-9, 75), 29% (1, 49), 13% (-21, 37) for the three seasons.

CONCLUSIONS

The register-based cohort design produced results more concordant with the active test-negative design than the case-control design. Furthermore, the register-based cohort design yielded most precise estimates with narrower confidence intervals. In Finland with the availability of near real-time nationwide register data, the register-based cohort design is the method of choice to continue the annual surveillance of influenza vaccine effectiveness.

High secondary attack rate and persistence of SARS-CoV-2 antibodies in household transmission study participants, Finland 2020–2021

Background

Household transmission studies offer the opportunity to assess both secondary attack rate (SAR) and persistence of SARS-CoV-2 antibodies over time.

Methods

In Spring 2020, we invited confirmed COVID-19 cases and their household members to four visits, where we collected nasopharyngeal and serum samples over 28 days after index case onset. We calculated SAR based on the presence of SARS-CoV-2 neutralizing antibodies (NAb) and assessed the persistence of NAb and IgG antibodies (Ab) against SARS-CoV-2 spike glycoprotein and nucleoprotein.

Results

SAR was 45% (39/87), including 35 symptomatic secondary cases. During the initial 28-day follow-up, 62% (80/129) of participants developed NAb. Of those that seroconverted, 90% (63/70), 85% (63/74), and 78% (45/58) still had NAb to early B-lineage SARS-CoV-2 3, 6, and 12 months after the onset of the index case. Anti-spike IgG Ab persisted in 100% (69/69), 97% (72/74), and 93% (55/59) of seroconverted participants after 3, 6, and 12 months, while anti-nucleoprotein IgG Ab levels waned faster, persisting in 99% (68/69), 78% (58/74), and 55% (39/71) of participants, respectively.

Conclusion

Following detection of a COVID-19 case in a household, other members had a high risk of becoming infected. NAb to early B-lineage SARS-CoV-2 persisted for at least a year in most cases.

Analysis of Thromboembolic and Thrombocytopenic Events After the AZD1222, BNT162b2, and MRNA-1273 COVID-19 Vaccines in 3 Nordic Countries

IMPORTANCE

Vaccinations are paramount to halt the COVID-19 pandemic, and safety data are essential to determine the risk-benefit ratio of each COVID-19 vaccine.

OBJECTIVE

To evaluate the association between the AZD1222, BNT162b2, and mRNA-1273 vaccines and subsequent thromboembolic and thrombocytopenic events.

DESIGN, SETTING, AND PARTICIPANTS

This self-controlled case series used individual-level data from national registries in Norway, Finland, and Denmark. Participants included individuals with hospital contacts because of coronary artery disease, coagulation disorders, or cerebrovascular disease between January 1, 2020, and May 16, 2021.

EXPOSURES

AZD1222, BNT162b2, or mRNA-1273 vaccine.

MAIN OUTCOMES AND MEASURE

Relative rate (RR) of hospital contacts for coronary artery disease, coagulation disorders, or cerebrovascular disease in a 28-day period following vaccination compared with the control period prior to vaccination.

RESULTS

We found 265 339 hospital contacts, of whom 112 984 [43%] were for female patients, 246 092 [93%] were for patients born in 1971 or earlier, 116 931 [44%] were for coronary artery disease, 55 445 [21%] were for coagulation disorders, and 92 963 [35%] were for cerebrovascular disease. In the 28-day period following vaccination, there was an increased rate of coronary artery disease following mRNA-1273 vaccination (RR, 1.13 [95% CI, 1.02-1.25]), but not following AZD1222 vaccination (RR, 0.92 [95% CI, 0.82-1.03]) or BNT162b2 vaccination (RR, 0.96 [95% CI, 0.92-0.99]). There was an observed increased rate of coagulation disorders following all 3 vaccines (AZD1222: RR, 2.01 [95% CI, 1.75-2.31]; BNT162b2: RR, 1.12 [95% CI, 1.07-1.19]; and mRNA-1273: RR, 1.26 [95% CI, 1.07-1.47]). There was also an observed increased rate of cerebrovascular disease following all 3 vaccines (AZD1222: RR, 1.32 [95% CI, 1.16-1.52]; BNT162b2: RR, 1.09 [95% CI, 1.05-1.13]; and mRNA-1273: RR, 1.21 [95% CI, 1.09-1.35]). For individual diseases within the main outcomes, 2 notably high rates were observed: 12.04 (95% CI, 5.37-26.99) for cerebral venous thrombosis and 4.29 (95% CI, 2.96-6.20) for thrombocytopenia, corresponding to 1.6 (95% CI, 0.6-2.6) and 4.9 (95% CI, 2.9-6.9) excess events per 100 000 doses, respectively, following AZD1222 vaccination.

CONCLUSIONS AND RELEVANCE

In this self-controlled case series, there was an increased rate of hospital contacts because of coagulation disorders and cerebrovascular disease, especially for thrombocytopenia and cerebral venous thrombosis, following vaccination with AZD1222. Although increased rates of several thromboembolic and thrombocytopenic outcomes following BNT162b2 and mRNA-1273 vaccination were observed, these increases were less than the rates observed after AZD1222, and sensitivity analyses were not consistent. Confirmatory analysis on the 2 mRNA vaccines by other methods are warranted.

Hospital Contacts for Infectious Diseases Among Children in Denmark, Finland, Norway, and Sweden, 2008-2017

Purpose

Comparing rates of childhood infectious disease hospitalisations across countries may uncover areas for improvement in the prevention of severe childhood infections. We compared rates of childhood infectious disease hospital contacts across Denmark, Finland, Norway, and Sweden with the overall objective to elucidate potential differences in burden of disease and in organisational and registration practices.

Methods

Using national registries, we estimated incidence rates for infectious disease hospital contacts between 2008 and 2017 among children aged 0–14 years. We investigated the rates for different types of contacts (inpatient or outpatient including emergency room), duration of admission, and by sex.

Results

During the study period, the rate of all hospital contacts per 1000 person-years was highest in Sweden (125.2) followed by Finland (87.1), Denmark (79.0), and Norway (62.1). The rates aligned for inpatient contacts with overnight stays; 19.3 (Denmark), 16.6 (Finland), 16.3 (Norway), and 13.0 (Sweden); these were highest in early infancy in all countries. A peak around 1 year of age was seen in all countries except in Sweden. The rates were higher among boys compared with girls in early childhood, after 13 years of age the rates among girls surpassed the boys.

Conclusion

Large cross-country differences were observed for outpatient and short-term hospital contacts for infectious diseases, affected by differences in organisational structures and coding practices across and within countries over time. Inpatient contacts requiring overnight stays reflected more comparable levels of severe infections across countries. Childhood infectious disease morbidity was greatest among boys and before 2 years of age.

Neutralizing antibodies to SARS-CoV-2 Omicron variant after third mRNA vaccination in health care workers and elderly subjects

The emergence of SARS-CoV-2 Omicron variant (B.1.1.529) with major spike protein mutations has raised concern over potential neutralization escape and breakthrough infections among vaccinated and previously SARS-CoV-2-infected subjects. We measured cross-protective antibodies against variants in health care workers (HCW, n = 20) and nursing home residents (n = 9) from samples collected at 1-2 months, following the booster (3rd) dose. We also assessed the antibody responses in subjects infected before the Omicron era (n = 38) with subsequent administration of a single mRNA vaccine dose. Following booster vaccination, HCWs had high IgG antibody concentrations to the spike protein and neutralizing antibodies (NAb) were detectable against all variants. IgG concentrations among the elderly remained lower, and some lacked NAbs against the Beta and Omicron variants. NAb titers were significantly reduced against Delta, Beta, and Omicron compared to WT virus regardless of age. Vaccination induced high IgG concentrations and variable titers of cross-reactive NAbs in previously infected subjects, whereas NAb titers against Omicron were barely detectable 1 month postinfection. High IgG concentrations with cross-protective neutralizing activity were detected after three Coronavirus Disease 2019 (COVID-19) vaccine doses in HCWs. However, lower NAb titers seen in the frail elderly suggest inadequate protection against Omicron breakthrough infections, yet protection against severe COVID-19 is expected.

Cohort study of Covid-19 vaccine effectiveness among healthcare workers in Finland, December 2020 - October 2021

Recently, Covid-19 vaccine effectiveness has decreased especially against mild disease due to emergence of the Delta variant and waning protection. In this register-based study among healthcare workers in Finland, the vaccine effectiveness of two-dose mRNA vaccine series against SARS-CoV-2 infection decreased from 82% (95% CI 79-85%) 14-90 days after vaccination to 53% (43-62%) after 6 months. Similar trend was observed for other series. Waning was not observed against Covid-19 hospitalization. These results facilitate decision-making of booster doses for healthcare workers.

A cluster-randomised, non-inferiority trial of the impact of a two-dose compared to three-dose schedule of pneumococcal conjugate vaccination in rural Gambia: the PVS trial

BACKGROUND

Pneumococcal conjugate vaccines (PCV) effectively prevent pneumococcal disease but the global impact of pneumococcal vaccination is hampered by the cost of PCV. The relevance and feasibility of trials of reduced dose schedules is greatest in middle- and low-income countries, such as The Gambia, where PCV has been introduced with good disease control but where transmission of vaccine-type pneumococci persists. We are conducting a large cluster-randomised, non-inferiority, field trial of an alternative reduced dose schedule of PCV compared to the standard schedule, the PVS trial.

METHODS

PVS is a prospective, cluster-randomised, non-inferiority, real-world field trial of an alternative schedule of one dose of PCV scheduled at age 6 weeks with a booster dose at age 9 months (i.e. the alternative '1 + 1' schedule) compared to the standard schedule of three primary doses scheduled at 6, 10, and 14 weeks of age (i.e. the standard '3 + 0' schedule). The intervention will be delivered for 4 years. The primary endpoint is the population-level prevalence of nasopharyngeal vaccine-type pneumococcal carriage in children aged 2 weeks to 59 months with clinical pneumonia in year 4 of the trial. Participants and field staff are not masked to group allocation while measurement of the laboratory endpoint will be masked. Sixty-eight geographic population clusters have been randomly allocated, in a 1:1 ratio, to each schedule and all resident infants are eligible for enrolment. All resident children less than 5 years of age are under continuous surveillance for clinical safety endpoints measured at 11 health facilities; invasive pneumococcal disease, radiological pneumonia, clinical pneumonia, and hospitalisations. Secondary endpoints include the population-level prevalence of nasopharyngeal vaccine-type pneumococcal carriage in years 2 and 4 and vaccine-type carriage prevalence in unimmunised infants aged 6-12 weeks in year 4. The trial includes components of mathematical modelling, health economics, and health systems research.

DISCUSSION

Analysis will account for potential non-independence of measurements by cluster, comparing the population-level impact of the two schedules with interpretation at the individual level. The non-inferiority margin is informed by the 'acceptable loss of effect' of the alternative compared to the standard schedule. The secondary endpoints will provide substantial evidence to support the interpretation of the primary endpoint. PVS will evaluate the effect of transition from a standard 3+ 0 schedule to an alternative 1 + 1 schedule in a setting of high pneumococcal transmission. The results of PVS will inform global decision-making concerning the use of reduced-dose PCV schedules.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial Number 15056916 . Registered on 15 November 2018.

Persistence of neutralizing antibodies a year after SARS-CoV-2 infection in humans

Most subjects develop antibodies to SARS‐CoV‐2 following infection. In order to estimate the duration of immunity induced by SARS‐CoV‐2 it is important to understand for how long antibodies persist after infection in humans. Here, we assessed the persistence of serum antibodies following WT SARS‐CoV‐2 infection at 8 and 13 months after diagnosis in 367 individuals. The SARS‐CoV‐2 spike IgG (S‐IgG) and nucleoprotein IgG (N‐IgG) concentrations and the proportion of subjects with neutralizing antibodies (NAb) were assessed. Moreover, the NAb titers among a smaller subset of participants (n = 78) against a WT virus (B) and variants of concern (VOCs): Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.2) were determined. We found that NAb against the WT virus persisted in 89% and S‐IgG in 97% of subjects for at least 13 months after infection. Only 36% had N‐IgG by 13 months. The mean S‐IgG concentrations declined from 8 to 13 months by less than one third; N‐IgG concentrations declined by two‐thirds. Subjects with severe infection had markedly higher IgG and NAb levels and are expected to remain seropositive for longer. Significantly lower NAb titers against the variants compared to the WT virus, especially after a mild disease, suggests reduced protection against VOCs.

Long-term population effects of infant 10-valent pneumococcal conjugate vaccination on pneumococcal meningitis in Finland

BACKGROUND

No previous studies have reported long-term follow-up of ten-valent pneumococcal conjugate vaccine (PCV10) program impact on pneumococcal meningitis (PM). We assessed the effects of infant PCV10 program on PM incidence, mortality and serotype distribution in children and adults during 7 years after introduction.

METHODS

We conducted a population-based observational study. A case of PM was defined as isolation of Streptococcus pneumoniae from cerebrospinal fluid or, a patient with S. pneumoniae isolated from blood and an ICD-10 hospital discharge diagnosis of bacterial meningitis within 30 days before or after positive culture date.We compared age- and serotype-specific incidence and associated 30-day mortality rates in 2011-2017 (PCV10 period) with those in 2004-2010 (pre-PCV10 baseline) by using Poisson regression models. Absolute rate differences and 95% confidence intervals (CIs) were calculated from the parameter estimates by using delta method.

RESULTS

During the PCV10 period, the overall incidence of PCV10 serotype meningitis decreased by 68% (95%CI 57%-77%), and the overall PM incidence by 27% (95%CI: 12%-39%). In age groups 0-4, 50-64, and ≥ 18 years, the overall PM incidence was reduced by 64%, 34% and 19%, respectively. In adults ≥ 65 years of age, a 69% reduction in PCV10 serotypes was offset by 157% (56%-342%) increase in non-PCV10 serotypes. The overall PM-related mortality rate decreased by 42% (95%CI 4%-65%). Overall case fatality proportion (CFP) was 16% in pre-PCV10 period and 12% in PCV10 period (p = 0.41); among persons 50-64 years the CFP decreased from 25% to 10% (p = 0.04).

CONCLUSIONS

We observed substantial impact and herd protection for vaccine-serotype PM and associated mortality after infant PCV10 introduction. However, in older adults ≥ 65 years of age, PM burden remains unchanged due to serotype replacement.

Similar impact and replacement disease after pneumococcal conjugate vaccine introduction in hospitalised children with invasive pneumococcal disease in Europe and North America

High incidence of childhood invasive pneumococcal disease (IPD) in the US declined steeply after 7-valent pneumococcal conjugate vaccine (PCV7) introduction, outweighing reductions observed elsewhere. We re-analysed aggregate published data and compared pre- and post-PCV IPD-incidence in different countries to explore PCV impact on hospitalised and outpatient IPD separately. The proportion of hospitalised IPD cases was consistently high (>80%) in England&Wales, Finland, the Netherlands, and Quebec/Canada, but only 32% in the US before PCV introduction, increasing to 69% during the PCV era. In the US, a higher reduction in outpatient IPD incidence (94% in 2015 versus 1998-99) was observed compared to hospitalised IPD (79%); a 51% reduction in the non-PCV13-type IPD incidence among outpatient cases was estimated compared to a >2-fold increase for hospitalised cases. After stratification by hospitalization status, PCV programmes resulted in similar impact and serotype replacement in hospitalised IPD in US when compared to other countries.

Effectiveness of the 10-valent pneumococcal conjugate vaccine among girls, boys, preterm and low-birth-weight infants - Results from a randomized, double-blind vaccine trial

BACKGROUND

Several studies have shown differences in susceptibility to infections and immune response to vaccines by sex. Prematurely born infants are at higher risk for pneumococcal diseases, with lower effectiveness for some vaccines compared to term infants. We have reported the effectiveness of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) on several endpoints in the Finnish Invasive Pneumococcal disease (FinIP) vaccine trial. Now, we present the results of a post-hoc analysis evaluating PHiD-CV10 effectiveness in subgroups by sex, gestational age, and birth weight.

METHODS

The FinIP trial was a phase III/IV cluster-randomized, double-blind trial. Infants enrolled < 7 months of age received PHiD-CV10 in two thirds of clusters (3 + 1 or 2 + 1 schedule) and hepatitis B vaccine as control in remaining third. Outcome data included invasive pneumococcal disease, pneumonia, tympanostomy tube placements, and antimicrobial purchases collected through national, routinely used health registers. Negative binomial model was used in the incidence and vaccine effectiveness estimation, and differences in incidences between subgroups were tested among control children.

RESULTS

Of the 30,527 infants enrolled 51% were boys. The incidences of hospital-diagnosed pneumonia and otitis-related outcomes were higher among boys in control groups. There were no significant sex differences in the vaccine effectiveness estimates. Altogether, 1519 (5%) infants were born before 37th gestational week. The incidences of pneumonia outcomes were higher among premature infants when compared to term infants. The vaccine effectiveness estimates among preterm infants were not statistically significant except for antimicrobial purchases, but all point estimates were at the same level among preterm infants as among term infants. There was no significant difference between 2 + 1 and 3 + 1 schedules in any of the subgroups analysed.

CONCLUSION

PHiD-CV10 had a similar effectiveness in both sexes, and seemed to be protective in preterm infants.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00861380 and NCT00839254.

Culture of all sputum samples irrespective of quality adds value to the diagnosis of pneumococcal community-acquired pneumonia in the elderly

Culture of expectorated sputum in the microbiological diagnosis of community-acquired pneumonia (CAP) is considered valid only if high-quality (HQ) samples are obtained, but evidence regarding pneumococcal etiology specifically is lacking. We studied 323 radiologically confirmed CAP cases in patients aged ≥ 65 years. Sputum samples were assessed for quality microscopically and cultured. Two quality criteria sets were applied to delineate HQ from low-quality (LQ) sputa: leukocytes/epithelial cells ratio > 5 and ≤ 2.5 epithelial cells/400× magnification field (HQ1), or leukocytes/epithelial cells ratio > 1 (HQ2). A sputum sample was obtained and the quality assessed in 224 cases; 47% were HQ1 and 76% HQ2. Encapsulated pneumococci (EPnc) were cultured in 25 (24%), 14 (12%), 35 (21%), and 4 (7%) of the HQ1-, LQ1-, HQ2-, and LQ2-samples, respectively. If another pneumococcal test (blood culture, urine antigen, or ≥ twofold increase in CbpA or PsaA antibodies) was positive, EPnc were cultured at similar proportions in HQ1- and LQ1-sputa; if the other test was negative, EPnc were cultured less often in LQ1- than HQ1-sputa. EPnc were found less often in LQ2- than in HQ2-sputa. Our results suggest similar specificity in LQ- and HQ-sputum cultures. All sputum samples add value to the pneumococcal CAP-diagnosis in the elderly.

Nasal swab bacteriology by PCR during the first 24-months of life: A prospective birth cohort study

BACKGROUND

Most respiratory bacterial carriage studies in children are based on cross-sectional samples or longitudinal studies with infrequent sampling points. The prospective Observational Research in Childhood Infectious Diseases birth cohort study intensively evaluated the community-based epidemiology of respiratory viruses and bacteria during the first 2-years of life. Here we report the bacteriologic findings.

METHODS

Pregnant women in Brisbane, Australia were recruited between September 2010 and October 2012, and their healthy newborn children were followed for the first 2-years of life. Parents kept a daily symptom diary for the study child, collected a weekly anterior nose swab and completed an illness burden diary when their child met pre-defined illness criteria. Specimens were tested for respiratory bacteria by real-time polymerase chain reaction (PCR) assays and those containing human genomic DNA, deemed as high-quality, were analyzed.

RESULTS

Altogether 8100 high-quality nasal swab specimens from 158 enrolled children were analyzed. Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae were detected in 42.4%, 38.9%, and 14.8% of these samples, respectively. Concomitant detection of bacteria was common. In contrast, Bordetella pertussis, B. parapertussis, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Simkania negevensis were rarely identified. The prevalence of the three major bacteria was higher with increasing age and in the winter and spring months. Siblings and childcare attendance were the other risk factors identified.

CONCLUSIONS

We confirmed the feasibility of frequent nasal swabbing by parents for studying bacterial colonization. PCR detected the major respiratory tract bacteria with expected high frequencies, but atypical bacteria were found rarely in this cohort.

Effectiveness and impact of the 10-valent pneumococcal conjugate vaccine, PHiD-CV: review of clinical trials and post-marketing experience

INTRODUCTION

Pneumococcal diseases (including septicemia, meningitis, pneumonia, and upper respiratory infections) constitute a major public health problem. The World Health Organization recommends pneumococcal conjugate vaccine immunization of young children worldwide.

AREAS COVERED

We reviewed evidence on the effects of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV), which is used in childhood immunization programs in over 45 countries or regions. The effectiveness of PHiD-CV against invasive pneumococcal disease (IPD), pneumonia, and acute otitis media was assessed. We also present its effect on pneumococcal nasopharyngeal carriage (NPC) and indirect effects (herd protection) among unvaccinated individuals.

EXPERT COMMENTARY

Results from randomized, double-blind trials and post-marketing studies in various countries provide evidence of the protective efficacy, effectiveness, and impact of PHiD-CV against pneumococcal diseases. Data from different geographic locations also show reductions in NPC of vaccine pneumococcal serotypes, laying the foundation for indirect protection against pneumococcal disease. In countries where PHiD-CV is included in childhood immunization programs, there are signs of herd protection for vaccine serotypes among unvaccinated individuals. Although increases in non-vaccine serotype IPD and NPC rates were observed, there was an overall reduction of pneumococcal disease.

The prevalence of otitis media in 2-3 year old Cameroonian children estimated by tympanometry

BACKGROUND

Acute otitis media is a common illness in children under-five years of age and associated with major health care resources in high-income countries. However, there is paucity of data on its epidemiology and clinical presentation in low-income countries. We estimated the prevalence of otitis media and assessed risk factors among children in Cameroon.

METHODS

A community-based cross-sectional prevalence study of otitis media (OM) was performed on randomly selected children aged 2-3 years in Yaoundé, Cameroon from March to June 2013. OM was assessed by clinical inspection for chronic suppurative otitis media (CSOM) and tympanometry for otitis media with effusion (OME). CSOM was defined as draining of the middle ear with duration of more than two weeks and OME was defined as a flat 'type B' tympanogram.

RESULTS

Out of 529 children enrolled in the study, 433 (56% males) subjects with available tympanograms were evaluated. Altogether, 9.7% (42/433) of children met the case definition of CSOM, OME or its complications. This consisted of 3 (0.7%) children identified with unilateral CSOM; 7 (1.6%) children with bilateral OME; 31 (7.2%) with unilateral OME and 1 (0.2%) subject with unilateral dry tympanic membrane perforation. Logistic regression analyses showed statistically significant association between OM and parental reporting of "current symptoms of upper respiratory tract infections", Prevalence Odds Ratio (POR) = 3.71; 95% CI = 1.69-8.14).

CONCLUSION

As many as two out of a hundred children between the ages of 2-3 years were affected by significant middle ear disease i.e. CSOM or bilateral OME. These data could be useful as a baseline for estimating the impact of pneumococcal conjugate vaccines (PCV13) introduced in July 2011 for infants in Cameroon.

Register-Based Ecologic Evaluation of Safety Signals Related to Pneumococcal Conjugate Vaccine in Children

Background:

In clinical trials of Pneumococcal Conjugate Vaccines (PCV), some adverse events have been reported more frequently in the PCV vaccinated. Ten-valent PCV (PCV10) was introduced into the Finnish National Vaccination Programme (NVP) in September 2010.

Objective:

We conducted an ecologic register-based study to investigate further the reported adverse events after PCV.

Methods:

This study included data obtained from the Finnish nationwide, population-based registers. First diagnoses of febrile seizures, breath-holding, urticarial rash, asthma and Kawasaki’s disease were included as outcomes obtained from the hospital discharge register. Data from Finnish Population Register during 2000-2014 for children age from 3 months to 10 years were used to estimate annual incidence rates. Incidence rate ratios of the outcomes were calculated between the target cohort of children eligible for PCV10 during 2010-2014 and a reference cohort before the NVP introduction (2004-2008).

Results:

No increases in the incidence of the adverse events after PCV10 introduction were found except for urticarial rash (incidence rate 2.48 vs. 1.60/1000 pyrs; incidence rate ratio, 1.54;95% CI 1.42-1.67). This increase was seen also in the unvaccinated older age groups in the post-vaccination era. The higher incidence of urticarial rash after the PCV10 introduction was due to the inclusion of diagnoses made in general medicine specialty in the discharge register because of a concomitant administrative change.

Conclusion:

The results do not support public health concerns related to the previously reported adverse events. Concomitant changes in health care administration and coding introduced bias, which was controlled after further evaluation of the data. We consider this register-based approach with real-world data feasible in the signal validation process after any signal detection.

Vaccine-preventable disease incidence of pneumococcal conjugate vaccine in the Finnish invasive pneumococcal disease vaccine trial

Estimation of the full disease burden caused by Streptococcus pneumoniae is challenging due to the difficulties in assigning the aetiology especially in lower and upper respiratory infections. We estimated the pneumococcal disease burden by using the vaccine-preventable disease incidence (VPDI) of PHiD-CV10 vaccine (GSK) in our clinical trial setting. Finnish Invasive Pneumococcal disease (FinIP) trial was a cluster-randomized, double-blind trial in children <19 months who received PHiD-CV10 in 52 clusters or hepatitis B/A vaccine as control in 26 clusters according to 3+1 or 2+1 schedules (infants < 7 months) or catch-up schedules (children 7-18 months). Outcome data were collected using Finnish routine health-care registers, consisting of THL National Infectious Diseases Register, THL Care register, and Benefits Register of Social Insurance Institution of Finland. Blinded follow-up lasted from the date of first vaccination (trial enrolment Feb-2009 through Aug-2010) to January 31, 2012 for Invasive Pneumococcal Disease (IPD) and to end of December 2011 for four other outcomes: non-laboratory-confirmed IPD, hospital-diagnosed pneumonia, tympanostomy tube placements, and antimicrobial purchases. VPDI was estimated as difference in disease incidences between PHiD-CV10 clusters and control clusters. Altogether >47,000 children were enrolled. In 30,527 vaccinated infants <7 months at first dose, the VPDIs per 100,000 person-years were 75 for laboratory-confirmed IPD, 210 for non-laboratory-confirmed IPD, 271 for hospital-diagnosed pneumonia, 1143 for any tympanostomy tube placements and 11,381 for antimicrobial outpatient prescription, mainly due to otitis media. In a European developed-country setting, over 95% of the disease episode reductions in vaccinated children were seen in mild upper respiratory infections. The VPDIs of severe diseases are underestimated, because the majority of invasive disease goes undetected with routine blood-culture-based definitions. Evaluation of the absolute reduction achievable with vaccinations using sensitive case detection is essential for understanding the full disease burden, for valid cost-effectiveness analyses and for appropriate vaccination policy decisions. Registration: ClinicalTrials.gov, NCT00861380 and NCT00839254.

The association of adverse events with bivalent human papilloma virus vaccination: A nationwide register-based cohort study in Finland

BACKGROUND

A bivalent HPV vaccine (Cervarix®; HPV2, GlaxoSmithKline) was introduced into the Finnish national vaccination programme (NVP) in November 2013 for girls aged 11-13 years with a catch-up for 14-15 year-olds. We evaluated the association between HPV2 and selected autoimmune diseases and clinical syndromes by conducting a nation-wide retrospective register-based cohort study.

METHODS

First life-time occurrences of the relevant ICD-10 codes in girls aged 11-15 years between Nov-2013 and Dec-2016 were obtained from the national hospital discharge register. Population denominators were obtained from the Population Information System and vaccination records from the National Vaccination Register. Registers were linked using unique personal identity codes. Association between HPV2 and 38 selected outcomes were studied using Cox regression, with age as the main time-scale and the first vaccination dose as the time-dependent exposure. The hazard ratios (HR) with 95%CI were assessed according to the time since exposure (entire follow-up, 0-180/181-365/>365 days).

RESULTS

Of 240 605 girls eligible for HPV2 vaccination, 134 615 (56%) were vaccinated. After adjustment for geographical area (6 hospital districts), country of origin (Finnish-born/not) and number of hospital contacts from 9 through 10 years of age, HRs ranged from 0.34 (95%CI 0.11-1.05) to 8.37 (95%CI 0.85-82.54) and HPV2 vaccination was not statistically significantly associated with a higher risk of any outcome during the entire follow-up.

CONCLUSIONS

This study found no significantly increased risk for the selected outcomes after the HPV vaccination in girls 11-15 years of age. These results provide valid evidence to counterbalance public scepticism, fears of adverse events and possible opposition to HPV vaccination and consequently can contribute to increase HPV vaccination coverage in Finland as well as elsewhere.

Testing Pneumonia Vaccines in the Elderly: Determining a Case Definition for Pneumococcal Pneumonia in the Absence of a Gold Standard

Clinical assessments of vaccines to prevent pneumococcal community-acquired pneumonia (CAP) require sensitive and specific case definitions, but there is no gold standard diagnostic test. To develop a new case definition suitable for vaccine efficacy studies, we applied latent class analysis (LCA) to the results from 7 diagnostic tests for pneumococcal etiology on clinical specimens from 323 elderly persons with radiologically confirmed pneumonia enrolled in the Finnish Community-Acquired Pneumonia Epidemiology study during 2005-2007. Compared with the conventional use of LCA, which is mainly to determine sensitivities and specificities of different tests, we instead used LCA as an appropriate instrument to predict the probability of pneumococcal etiology for each CAP case based on individual test profiles, and we used the predictions to minimize the sample size that would be needed for a vaccine efficacy trial. When compared with the conventional laboratory criteria of encapsulated pneumococci in culture, in blood culture or high-quality sputum culture, or urine antigen positivity, our optimized case definition for pneumococcal CAP resulted in a trial sample size that was almost 20,000 subjects smaller. We believe that the novel application of LCA detailed here to determine a case definition for pneumococcal CAP could also be similarly applied to other diseases without a gold standard.

A pneumococcal conjugate vaccination programme reduced clinically suspected invasive disease in unvaccinated children

AIM

The 10-valent pneumococcal conjugate vaccine was introduced to the Finnish national vaccination programme for children born since June 2010. We evaluated the changes in the rates of clinically suspected invasive pneumococcal disease (IPD) in unvaccinated children to estimate the indirect herd protection impact of the programme.

METHODS

The target cohort for this ecological before and after comparison were unvaccinated children born from January 2008 to May 2010 and ineligible for the vaccination programme, who were followed up from 2011 to 2014. The reference cohort was age and season-matched children born in January 2003 to 2005 and followed up from 2006 to 2009. National data on hospital discharge codes compatible with IPD or unspecified sepsis were collected.

RESULTS

We compared the follow-up periods of 2007-2009 in the reference cohort and 2012-2014 in the target cohort. The incidence of non-laboratory-confirmed IPD in unvaccinated children fell by 68%, from 47 to 15/100 000 person-years. When unspecified sepsis was added, the decrease was 39%, from 171 to 104/100 000 person-years. Laboratory confirmed IPD fell by 44%, from 15 to 8/100 000 person-years.

CONCLUSION

The pneumococcal vaccination programme provided herd protection against clinically suspected IPD. The absolute reduction was almost 10-times higher than for just laboratory-confirmed disease.

Population-level impact of infant 10-valent pneumococcal conjugate vaccination on adult pneumonia hospitalisations in Finland

Introduction

Limited data are available on population-level herd effects of infant 10-valent pneumococcal conjugate vaccine (PCV10) programmes on pneumonia. We assessed national trends in pneumococcal and all-cause pneumonia hospitalisations in adults aged ≥18 years, before and after infant PCV10 introduction in 2010.

Methods

Monthly hospitalisation rates of International Statistical Classification of Diseases, 10th revision (ICD-10)-coded primary discharge diagnoses compatible with pneumonia from 2004–2005 to 2014–2015 were calculated with population denominators from the population register. Trends in pneumonia before and after PCV10 introduction were assessed with interrupted time-series analysis. Rates during the PCV10 period were estimated from adjusted negative binomial regression model and compared with those projected as continuation of the pre-PCV10 trend. All-cause hospitalisations were assessed for control purposes.

Results

Before PCV10, the all-cause pneumonia rate in adults aged ≥18 years increased annually by 2.4%, followed by a 4.7% annual decline during the PCV10 period. In 2014–2015, the overall all-cause pneumonia hospitalisation rate was 109.3/100 000 (95% CI 96.5 to 121.9) or 15.4% lower than the expected rate. A significant 6.7% decline was seen in persons aged ≥65 years (131.5/100 000), which translates to 1456 fewer pneumonia hospitalisations annually. In comparison, hospitalisations other than pneumonia decreased by 3.5% annually throughout the entire study period.

Conclusion

These national data suggest that herd protection from infant PCV10 programme has reversed the increasing trend and substantially decreased all-cause pneumonia hospitalisations in adults, particularly the elderly.

Similar Antibody Levels in 3-Year-Old Children Vaccinated Against Measles, Mumps, and Rubella at the Age of 12 Months or 18 Months

BACKGROUND

Measles-mumps-rubella (MMR) vaccinations have been offered to Finnish children at 14-18 months and 6 years of age. In May 2011, the recommended age for the first vaccine dose was lowered to 12 months because of the European measles epidemic.

METHODS

Fingertip capillary blood samples were collected from 3-year-old Finnish children vaccinated once with MMR vaccine at 11-19 months of age. The immunoglobulin G (IgG) antibodies to all 3 MMR antigens were measured with enzyme-linked immunosorbent assay. Neutralizing antibodies and the avidity of antibodies were measured for measles virus.

RESULTS

From April through October 2013, 187 children were enrolled. Equally high proportions of the samples were seropositive for measles virus, mumps virus, or rubella virus antibodies, and there were no significant differences in the IgG antibody concentrations in children vaccinated at 11-13 months of age, compared with those vaccinated at 17-19 months of age. However, among children vaccinated at 11-13 months of age, boys had lower antibody concentrations than girls. Neutralizing measles virus antibody titers were above the threshold for protective immunity in all 78 samples analyzed. The measles virus antibody avidity indexes were high for all children.

CONCLUSIONS

MMR induces similar antibody responses in 12-month-old children as compared to 18-month-old children, but in boys increasing age appears to improve the antibody responses.

Pneumococcal Conjugate Vaccine and Clinically Suspected Invasive Pneumococcal Disease

OBJECTIVE

Ten-valent pneumococcal conjugate vaccine (PCV10) was earlier shown to reduce clinically suspected, non-laboratory-confirmed invasive pneumococcal disease (IPD) in a cluster-randomized trial (the Finnish Invasive Pneumococcal disease trial). PCV10 was introduced into the Finnish national vaccination program in September 2010 using a 3-dose schedule. We evaluated the impact of PCV10 on clinically suspected IPD among vaccine-eligible children in a population-based nationwide study.

METHODS

The target cohort eligible for vaccination program (children born June 2010-September 2013) was compared with 2 season- and age-matched (ages 3-42 months) reference cohorts before PCV10 introduction. The trial period (January 2009-August 2010) was excluded. Hospitals' inpatient and outpatient discharge notifications with International Classification of Diseases, 10th Revision, diagnoses compatible with IPD (A40.3/B95.3/G00.1/M00.1) and unspecified sepsis (A40.9/A41.9/A49.9/G00/G00.9/I30.1/M00/M00.9/B95.5) were collected from the national Care Register. Laboratory-confirmed IPD cases were excluded. Rates of register-based non-laboratory-confirmed IPD (or unspecified sepsis) before and after PCV10 implementation were calculated.

RESULTS

The rate of register-based non-laboratory-confirmed IPD episodes was 32 in 100 000 person-years in the vaccine-eligible target cohort and 94 in the combined reference cohorts. Relative rate reduction was 66% (95% confidence interval: 59-73) and absolute rate reduction 62 in 100 000 person-years. For the more sensitive case definition of register-based non-laboratory-confirmed IPD or unspecified sepsis, the relative rate reduction was 34% (95% confidence interval 29-39), but the absolute reduction was as high as 122 in 100 000 person-years.

CONCLUSIONS

This is the first report demonstrating nationwide PCV impact on clinically suspected IPD during routine vaccination program. The large absolute rate reductions observed have major implications for cost-effectiveness of PCVs.

Vaccine effectiveness of the pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) against clinically suspected invasive pneumococcal disease: a cluster-randomised trial

BACKGROUND

Vaccine effectiveness of pneumococcal conjugate vaccines against culture-confirmed invasive pneumococcal disease has been well documented. In the Finnish Invasive Pneumococcal disease (FinIP) trial, we reported vaccine effectiveness and absolute rate reduction against laboratory-confirmed invasive pneumococcal disease (confirmation by culture or antigen or DNA detection irrespective of serotype). Here, we assessed vaccine effectiveness of PHiD-CV10 against clinically suspected invasive pneumococcal disease in children by use of diagnoses coded in hospital discharge registers.

METHODS

For this phase 3/4 cluster-randomised, double-blind trial, undertaken between Feb 18, 2009, and Dec 31, 2011, in municipal health-care centres and the Tampere University Vaccine Research Centre (Finland), we randomly assigned (2:2:1:1) 78 clusters into PHiD-CV10 three plus one, PHiD-CV10 two plus one, control three plus one, control two plus one groups (26:26:13:13 clusters) to give PHiD-CV10 in either three plus one or two plus one schedule (if enrolled before 7 months of age; infant schedules), two plus one (if enrolled between 7 and 11 months; catch-up schedules), and two doses at least 6 months apart (if enrolled between 12 and 18 months; catch-up schedules). Children were eligible if they had not received and were not anticipated to receive any of the study vaccines and had no general contraindications to vaccinations. We collected all inpatient and outpatient discharge notifications from the national hospital discharge register with International Classification of Diseases (ICD) 10 diagnoses compatible with invasive pneumococcal disease or unspecified sepsis, and verified data with patient files. We excluded invasive pneumococcal disease cases confirmed by positive culture or DNA/RNA detection from normally sterile body fluid. The primary objective was to estimate vaccine effectiveness against all register-based non-laboratory-confirmed invasive pneumococcal disease or unspecified sepsis and patient-file verified non-laboratory-confirmed invasive pneumococcal disease in infants younger than 7 months at enrolment. Masked follow-up lasted from the date of the first vaccination to Dec 31, 2011. Vaccine effectiveness was calculated against all episodes. This trial is registered with ClinicalTrials.gov, numbers NCT00861380 and NCT00839254.

FINDINGS

We enrolled 47,366 children. On the basis of ICD-10 diagnoses, we recorded 264 episodes of register-based non-laboratory-confirmed invasive pneumococcal disease or unspecified sepsis, of which 102 were patient-file verified non-laboratory-confirmed invasive pneumococcal disease. The vaccine effectiveness was 50% (95% CI 32-63) in the 30,527 infants with three plus one and two plus one schedules combined and the absolute incidence rate reduction was 207 episodes per 100,000 person-years (95% CI 127-286). The vaccine effectiveness against the patient-file verified non-laboratory-confirmed invasive pneumococcal disease was 71% (95% CI 52-83) in infant three plus one and two plus one schedules combined. The absolute rate reduction was 142 episodes per 100,000 person-years (95% CI 91-191) in infant cohorts.

INTERPRETATION

This vaccine-probe analysis is the first report showing the effect of pneumococcal conjugate vaccines on clinically suspected invasive pneumococcal disease. The absolute rate reduction was markedly higher compared with laboratory-confirmed invasive pneumococcal disease, which implies low sensitivity of the laboratory-based case definitions and subsequently higher public health effect of pneumococcal conjugate vaccines against invasive pneumococcal disease than previously estimated.

FUNDING

GlaxoSmithKline Biologicals SA and National Institute for Health and Welfare (THL), Finland.

Incidence and etiology of community-acquired pneumonia in the elderly in a prospective population-based study

BACKGROUND

We conducted a prospective population-based epidemiological study to prepare a setting for documentation of the efficacy of novel vaccines against pneumococcal (Pnc) community-acquired pneumonia (CAP) in the elderly. Specific objectives were to demonstrate setting feasibility, to construct a case definition for Pnc CAP, and to estimate its incidence.

METHODS

We prospectively enrolled patients with clinical and radiological findings compatible with CAP at municipal on-call clinics serving an elderly population (age ≥ 65 y) of approximately 29,500. Sputum, urine, nasopharyngeal swab (NPS), and blood samples were analyzed using diverse methods for the identification of Pnc (culture, PCR, antigen tests, serology) and of other pathogens. The following case definition for Pnc CAP was derived: encapsulated Pnc in blood culture or in high-quality sputum culture or at least 2 of the following: positive urine Pnc antigen; ≥ 2-fold increase in serum anti-PsaA or anti-CbpA antibodies; encapsulated Pnc culture or LytA PCR in either sputum or NPS.

RESULTS

We enrolled 490 clinical CAP patients during the 2-y follow-up, 53% of all clinical CAP patients in the source population; 323 were radiologically confirmed. The incidence of radiologically confirmed CAP was 5.5/1000 person-y (95% confidence interval (CI) 4.9-6.1) and 10.5/1000 person-y when adjusted for non-captured patients. The proportion of radiologically confirmed CAP caused by Pnc was estimated at 17%; i.e. 0.95/1000 person-y (95% CI 0.7-1.2) and 1.8 when adjusted for non-captured patients.

CONCLUSIONS

We developed and documented a feasible methodology for capturing endpoints in a vaccine trial for the prevention of pneumonia. CAP incidence in the elderly population remains considerable and Streptococcus pneumoniae was one of the most commonly detected causative agents.

Effectiveness of the ten-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) against invasive pneumococcal disease: a cluster randomised trial

BACKGROUND

The Finnish Invasive Pneumococcal disease (FinIP) vaccine trial was designed to assess the effectiveness of a pneumococcal vaccine containing ten serotype-specific polysaccharides conjugated to Haemophilus influenzae protein D, tetanus toxoid, and diphtheria toxoid as the carrier proteins (PHiD-CV10) against invasive pneumococcal disease.

METHODS

In this cluster-randomised, double-blind trial, children aged younger than 19 months received PHiD-CV10 in 52 clusters or hepatitis vaccines as control in 26 clusters. Infants aged younger than 7 months at the first vaccination received either a 3+1 or a 2+1 vaccination schedule, children aged 7-11 months received a 2+1 schedule, and those 12-18 months of age received a two-dose schedule. The primary and secondary objectives were to assess vaccine effectiveness against culture-confirmed invasive pneumococcal disease due to any of the ten vaccine serotypes for the 3+1 and 2+1 schedules, respectively, in children who received at least one PHiD-CV10 dose before 7 months of age. Masked follow-up of pneumococcal disease lasted from the first vaccination (from February, 2009, to October, 2010) to January 31, 2012. Invasive disease data were retrieved from data accumulated in the national infectious diseases register. This trial and the nested acute otitis media trial are registered with ClinicalTrials.gov, numbers NCT00861380 and NCT00839254, respectively.

FINDINGS

47,369 children were enrolled from February, 2009, to October, 2010. 30,528 participants were assessed for the primary objective. 13 culture-confirmed vaccine-type cases of invasive pneumococcal disease were detected: none in the PHiD-CV10 3+1 group, one in the PHiD-CV10 2+1 group, and 12 in the control groups. The estimates for vaccine effectiveness were 100% (95% CI 83-100) for PHiD-CV10 3+1 and 92% (58-100) for PHiD-CV10 2+1 groups. Two cases of any culture-confirmed invasive disease irrespective of serotype were detected in combined PHiD-CV10 infant cohorts compared with 14 in the corresponding control cohorts (vaccine effectiveness 93%, 75-99). In catch-up cohorts, seven cases of invasive disease were reported, all in the control group: two cases in the children enrolled at 7-11 months of age; and five cases in children enrolled at 12-18 months of age (vaccine effectiveness 100%, 79-100). Non-fatal serious adverse events suspected to be vaccine-related were reported via routine post-immunisation safety surveillance in 18 children.

INTERPRETATION

This nationwide trial showed high PHiD-CV10 effectiveness against invasive pneumococcal disease when given in different schedules. For the first time, effectiveness of a 2+1 schedule in infants was confirmed in a clinical trial.

FUNDING

GlaxoSmithKline Biologicals SA and National Institute for Health and Welfare, Finland.

Presence of capsular locus genes in immunochemically identified encapsulated and unencapsulated Streptococcus pneumoniae sputum isolates obtained from elderly patients with acute lower respiratory tract infection

The principal virulence factor of Streptococcus pneumoniae is capsular polysaccharide, and encapsulated pneumococci are more common causes of disease than unencapsulated strains. This study analysed the presence of capsular genes in 59 pneumococcal isolates using two PCR methods targeted at the cpsA and cpsB genes of the capsular biosynthesis locus. The PCR method targeted at the cpsB gene, reported to be essential for encapsulation, was developed in this study. Of 59 pneumococcal isolates, 49 (83 %) were obtained from the sputum samples of elderly patients (≥65 years) with community-acquired pneumonia (CAP) and 10 (17 %) were from those with other acute lower respiratory tract infections (ARIs). Forty (82 %) of the CAP isolates and two (20 %) of the ARI isolates were encapsulated, as assessed by conventional immunochemical methods. Forty-one (98 %) of the 42 encapsulated strains had the cpsB gene present, and in 38 strains the cpsA gene was also detected. One of the unencapsulated isolates gave a positive result for the cpsB gene, and neither of the capsular locus genes were present in all the other unencapsulated strains. The distribution of encapsulated and unencapsulated isolates differed significantly between the two patient groups regardless of whether the presence of capsule was determined immunochemically (P<0.001) or by cpsB PCR (P=0.002). The cpsB PCR developed here was found to be a rapid and reliable method to detect the pneumococcal capsule locus and may have potential in sputum diagnostics when investigating the pneumococcal aetiology of CAP.

Efficacy of pneumococcal conjugate vaccine against PCR-positive acute otitis media

We aimed to assess the efficacy of a pneumococcal conjugate vaccine against acute otitis media (AOM) positive by pneumolysin-PCR (Ply-PCR). 1662 infants vaccinated with PncCRM or control vaccine using random allocation were followed for AOM up to 24 months of age. When AOM was diagnosed a middle ear fluid sample was obtained for etiological assays. During the per protocol follow-up period the PncCRM vaccine efficacy was 19% against Ply-PCR-positive AOM but only 3% when culture-positive cases were excluded. The data do not support effect of PncCRM on AOM in which only Ply-PCR suggests pneumococcal etiology.

Bacterial etiology of acute myringitis in children less than two years of age

BACKGROUND

Acute myringitis is an inflammation of the tympanic membrane that occurs alone or in association with external otitis or otitis media. The two clinical entities, based on physical examination, are bullous myringitis and hemorrhagic myringitis.

OBJECTIVES

To investigate the association of concomitant middle ear disease with acute myringitis and to analyze the bacteriologic findings of the middle ear fluid in children with acute myringitis.

METHODS

A prospective longitudinal cohort study of 2028 children age 7 to 24 months at primary care level in the Finnish Otitis Media Vaccine Trial. Matched case-control design for analysis of bacterial pathogen distribution.

RESULTS

There were 82 children in whom 92 ears were diagnosed with acute bullous myringitis and 37 children in whom 40 ears were diagnosed with hemorrhagic myringitis during the follow-up. Middle ear disease was associated with bullous myringitis in 97% of ears and with hemorrhagic myringitis in 82% of ears. Bacterial pathogen distribution was similar to that of acute otitis media, although a higher proportion of Streptococcus pneumoniae was detected in both bullous and hemorrhagic acute myringitis.

CONCLUSIONS

Middle ear fluid was present in vast majority of ears with acute myringitis in young children. The same etiologic bacteria were found in acute myringitis as in acute otitis media, but S. pneumoniae was the major pathogen. Acute bullous myringitis should be treated as acute otitis media in children <2 years of age.