Estimated number of reported vaccine-preventable disease cases averted following the introduction of routine vaccination programs in Sweden, 1910-2019.

BACKGROUND: Routine childhood vaccination programs have had enormous positive public health impacts worldwide. However, in some areas, these benefits may be impeded by vaccine hesitancy and undervaccination. We estimated the number of reported cases of measles, pertussis, mumps and poliomyelitis averted in Sweden after the introduction of routine childhood vaccination programs. METHODS: We used annual national data on population size and the number of reported cases of measles (1911-2019), pertussis (1911-2019), mumps (1914-2019) and poliomyelitis (1910-2019) for Sweden. For each disease, we calculated the median and 95% confidence interval of the annual pre-vaccination incidence to estimate the number of counterfactual cases; that is, the estimated number of cases that would have been observed in the post-vaccination period had no vaccine been introduced (median incidence × average annual population). For the post-vaccination periods, we calculated reported cases averted and assumed all decreases were due to vaccines. RESULTS: In total, for all four diseases combined, over 2.1 million cases were reported over the respective surveillance periods. Since the introduction of vaccinations, we estimate that over 1.5 million reported cases of these four diseases combined have been averted: measles (633 091), pertussis (608 670), mumps (262 951) and poliomyelitis (58 240). However, due to underreporting, especially during pre-vaccination years, these are likely underestimates. CONCLUSIONS: Since the introduction of these routine childhood vaccination programs in Sweden, a substantial number of reported cases of vaccine-preventable diseases have been averted. Vigilance against both failure to vaccinate and undervaccination is necessary to prevent future increases of these vaccine-preventable diseases.

Primary diphtheria immunisation of adolescents and adults with low-dose vaccine, a survey of historic evidence from the literature.

The Public Health Agency of Sweden carried out a literature review on diphtheria vaccinations for seronegative people above 6 years of age with an uncertain vaccine history. The aim was to harmonise national Swedish recommendations with the current World Health Organization recommendations. There was no firm conclusion about dosage. Some low-dose vaccines used in the past had suboptimal potency, while others evoked adequate levels of antitoxin after three primary doses. We concluded that low-dose diphtheria vaccines that have been approved by a national medical products agency can be used for primary vaccination against diphtheria for individuals above 6 years of age.

National Swedish survey showed that child health services and routine immunisation programmes were resilient during the early COVID-19 pandemic.

AIM: Routine immunisation programmes are at risk of disruption due to the COVID-19 pandemic. This study aimed to investigate the resilience of the Swedish national immunisation programme for children up to the age of five years during the early stages of the pandemic. METHODS: This was a cross-sectional, web-based survey of regional child health offices in Sweden between 10 September and 9 October 2020. It explored the organisation of child health services during the early stages of the pandemic, focusing on routine child immunisation. RESULTS: All 21 Swedish regional child health offices responded. They stated that child immunisation had been prioritised, communication with families had been intensified and there was greater flexibility at all organisational levels of child health services. In addition, the vaccine supply was sustained and child health centres remained open. However, there were periodic staff shortages, increased numbers of health visits cancelled by parents and most parent education groups were paused. CONCLUSION: The Swedish immunisation programme was resilient during the early COVID-19 pandemic, thanks to sustainable organisation co-ordinated by Sweden's network of regional child health offices.

Global Landscape Review of Serotype-Specific Invasive Pneumococcal Disease Surveillance among Countries Using PCV10/13: The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) Project.

Serotype-specific surveillance for invasive pneumococcal disease (IPD) is essential for assessing the impact of 10- and 13-valent pneumococcal conjugate vaccines (PCV10/13). The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project aimed to evaluate the global evidence to estimate the impact of PCV10/13 by age, product, schedule, and syndrome. Here we systematically characterize and summarize the global landscape of routine serotype-specific IPD surveillance in PCV10/13-using countries and describe the subset that are included in PSERENADE. Of 138 countries using PCV10/13 as of 2018, we identified 109 with IPD surveillance systems, 76 of which met PSERENADE data collection eligibility criteria. PSERENADE received data from most (n = 63, 82.9%), yielding 240,639 post-PCV10/13 introduction IPD cases. Pediatric and adult surveillance was represented from all geographic regions but was limited from lower income and high-burden countries. In PSERENADE, 18 sites evaluated PCV10, 42 PCV13, and 17 both; 17 sites used a 3 + 0 schedule, 38 used 2 + 1, 13 used 3 + 1, and 9 used mixed schedules. With such a sizeable and generally representative dataset, PSERENADE will be able to conduct robust analyses to estimate PCV impact and inform policy at national and global levels regarding adult immunization, schedule, and product choice, including for higher valency PCVs on the horizon.

Cost-effectiveness of pneumococcal vaccination for elderly in Sweden.

INTRODUCTION: The aim was to assess cost-effectiveness of including pneumococcal vaccination for elderly in a national vaccination programme in Sweden, comparing health-effects and costs of pneumococcal related diseases with a vaccination programme versus no vaccination. METHOD: We used a single-cohort deterministic decision-tree model to simulate the current burden of pneumococcal disease in Sweden. The model accounted for invasive pneumococcal disease (IPD) and pneumonia caused by pneumococci. Costs included in the analysis were those incurred when treating pneumococcal disease, and acquisition and administration of the vaccine. Health effects were measured as quality-adjusted life years (QALY). The time-horizon was set to five years, both effects and costs were discounted by 3% annually. Health-effects and costs were accumulated over the time-horizon and used to create an incremental cost-effectiveness ratio. The 23-valent polysaccharide vaccine (PPV23) was used in the base-case analysis. The 13-valent pneumococcal conjugate vaccine PCV13 was included in sensitivity analyses. RESULTS: A vaccination programme using PPV23 would reduce the burden of pneumococcal related disease significantly, both when vaccinating a 65-year-old cohort and a 75-year-old cohort. IPD would decrease by 30% in the 65-year-old cohort, and by 29% in the 75-year-old cohort. The corresponding figures for CAP (communicable acquired pneumonia) are 19% and 15%. The cost per gained QALY was estimated to EUR 94,000 for vaccinating 65-year-olds and EUR 29,500 for 75-year-olds. With one dose PCV13 given instead of PPV23, the cost per gained QALY would increase by around 400% for both cohorts. The results were robust in sensitivity analyses. CONCLUSION: Introducing a vaccination programme against pneumococcal disease for 65-year-olds in Sweden is unlikely to be cost-effective, whereas it for 75 year-olds and using PPV23 can be considered good value for money. Our model indicates that vaccine price needs to be reduced by 55% for vaccination of 65-year-olds to be cost-effective, given a threshold of EUR 50,000.

Validation of the new Swedish vaccination register - Accuracy and completeness of register data.

OBJECTIVE: The aims of this study are to validate infant vaccination data in the Swedish Vaccination Register (SVR) to the Swedish administrative coverage reports, and to assess differences in register-based vaccination coverage estimates between providers using different data reporting methods. METHODS: The study population included all infants born in Sweden with a Swedish Personal Identity Number during 2014 and 2015 (n = 230,220). Data on all National Immunisation Programme vaccinations administered before 24 months of age were collected from the SVR and from administrative coverage reports. Information regarding data registration methods in the SVR were collected from national and regional authorities. Coverage from health care providers using single registration methods, where vaccination data were transferred automatically from the electronic health care record to the SVR, was compared to that from providers using double registration methods where data had to be added into the SVR in a separate process. RESULTS: For 98,4% of the study population at least one vaccination was recorded in the SVR. The coverage of 3-dose DTP-containing (87,1%) and 1 dose MMR (91,1%) in the register did not reach administrative data coverage (97,4% for 3-dose DTP-containing and 97,0% for MMR). Single registration procedures yielded significantly higher coverage than double registration procedures (92,24% vs 87,10%, p < 0,0001). A regional switch from double to single registration increased coverage from 80,0 to 95,2%. CONCLUSIONS: The SVR is a valuable data source for vaccination coverage monitoring. For research purposes, the SVR provides valuable data, since every health care provider is obliged to register all vaccine doses given within the national immunisation program. The SVR shows a high completeness validated by comparison to a very well-functioning administrative data system. Single-registration procedures give more complete data and should be supported by health systems while creating health care registers.

Mode of HPV vaccination delivery and equity in vaccine uptake: A nationwide cohort study.

Ten years after its introduction, equity in human papillomavirus (HPV) vaccine uptake remains unattained, not least for the groups at highest risk of cervical cancer. In Sweden, three different delivery modes of the vaccine have been in effect since May 2007. We used this as a natural experiment to investigate girls' HPV vaccine uptake in relation to parental country of birth and socioeconomic characteristics, by mode of delivery. Our nationwide study cohort comprised 689,676 girls born between 1990 and 2003. Data on HPV vaccination of the girls and parental birth/socioeconomic characteristics were retrieved from national registers. We examined the association between girls' vaccine uptake and parental characteristics, stratified by mode of delivery. The cumulative uptake of at least one dose of HPV vaccine was 37%, 48% and 79% for subsidised opportunistic, free-of-charge catch-up outside-school and free-of-charge school-based vaccination, respectively. In the subsidised vaccination, having parents born outside of Sweden, with low education and low family income was strongly associated with lower uptake [HR (95% confidence interval (CI)) = 0.49 (0.48-0.50), 0.32 (0.31-0.33), 0.53 (0.52-0.54), respectively]. The associations were partially reduced in catch-up outside-school, and strongly reduced in school-based vaccination delivery [HR (95% CI) =0.82 (0.81-0.83), 0.92 (0.91-0.94), 0.87 (0.85-0.88), respectively]. Free-of-charge school-based HPV vaccination achieved the highest uptake and displayed the least disparity in country of birth and socioeconomic background of the parents. This appears to be the most effective and equitable delivery mode for reaching high population vaccination coverage, including high-risk groups for cervical cancer.

[Polio close to eradication]. / Polio närmar sig utrotning.

Polio close to eradication The WHO Global Polio Eradication Initiative has been highly successful. With a dramatic decrease in polio since it started in 1988, the number of globally reported cases reached a record low of 37 in 2016. This article describes the WHO Endgame Strategic Plan including milestones that have been reached and challenges that have to be overcome in order to reach the goal of polio eradication by 2020. Efforts to strengthen immunizations systems and to detect and interrupt polio virus transmission focus on the three remaining endemic countries, namely Pakistan, Afghanistan and Nigeria. In 2016 the WHO took the first step to withdraw the oral polio vaccine (OPV) by globally shifting from trivalent to bivalent OPV.  The role of the inactivated vaccine (IPV) in the final phase of eradication and in the post-eradication situation is also considered. Certification of eradication and containment of all polio virus by the end of 2020 is a key objective. Legacy planning includes mainstreaming polio functions into ongoing public health programmes.

Pertussis vaccination in infancy lowers the incidence of pertussis disease and the rate of hospitalisation after one and two doses: analyses of 10 years of pertussis surveillance.

OBJECTIVES: Shortly after pertussis vaccination was reintroduced in Sweden in 1996, an intensified pertussis disease surveillance programme was set up. In this study, we report on in-depth analyses of age-dose-number-specific incidences and the rate of pertussis hospitalisation for children with no, 1 or 2 doses of an acellular pertussis vaccine before pertussis disease. Vaccine coverage, the timeliness of childhood vaccination and the effect of later than scheduled pertussis vaccination(s) are also examined. STUDY DESIGN: Children with notified laboratory-confirmed (culture or PCR) pertussis disease were evaluated among the surveillance population of about 1 million infants, born between 1996 and 2007 and followed for pertussis disease from October 1997 to December 2007, for nearly 6 million person-years. Birth and vaccination dates of the diseased children are known from the surveillance programme. To estimate denominators of the age-dose-number-specific pertussis incidences, we used birth and vaccination dates from a vaccine trial with more than 72,000 infants combined with national pertussis vaccine coverage data for children in the surveillance population. RESULTS: For infants from 3 to <5 months of age, the incidence of pertussis disease with at least 14 days of cough decreased from 264/100,000 for unvaccinated infants to 155/100,000 for infants with one dose of a pertussis vaccine prior to onset of the disease. In the age range 5 to <12 months, the age-dose specific incidences were 526, 95, and 24/100,000 for infants with no, 1 and 2 doses, respectively. The rate of hospitalisation for infants with 1 dose of a pertussis vaccine prior to onset of the disease was significantly lower than for unvaccinated infants of the same age. For many infants, there is a delay in administration of the vaccine doses according to the regular 3-5-12 month schedule (which has been the case for many years). Hypothetically, if all infants had been vaccinated exactly on schedule, we would expect about 28% fewer pertussis cases with at least 14 days of cough and 38% fewer hospitalisations due to pertussis, of cases possible to influence by vaccinations on schedule. CONCLUSION: Pertussis vaccination had a significant effect among infants already after the first dose. This is particularly important for premature infants and infants with severe respiratory and cardiac diseases. A moderate decrease in the incidence of pertussis disease in infants and rate of hospitalisation could be expected if primary vaccinations were carried out closer to the scheduled time than is currently the practice in Sweden.

Do we need a booster of Hib vaccine after primary vaccination? A study on anti-Hib seroprevalence in Sweden 5 and 15 years after the introduction of universal Hib vaccination related to notifications of invasive disease.

The prevalence of IgG ELISA antibodies against Haemophilus influenzae polyribosyl ribitol phosphate (anti-Hib) was studied in two Swedish seroepidemiologic materials. One study was performed in 1997 5 years after the introduction of universal Hib vaccination (N=3320). Ten years later, a similar study was carried out to analyze the effect of vaccination on anti-Hib prevalence (N=2383). The median values of anti-Hib concentrations (EU/mL) were almost identical in the two materials. The antigenic pressure including vaccination, natural infections and possible cross-immunizations was thus assumed to be constant. The joint median was 0.50 EU/mL (95% confidence interval: 0.46, 0.56). However, there were also indications of reduced exposure to 'Hib-antigens' over a 10-year period. The proportion above the cut-off point for protection, 0.15 EU/mL, decreased significantly for children aged 2-19 years from 78% in 1997 to 74% in 2007 (p=0.034), and there was a significant increase in values below the minimal level of detection for adults from 17% in 1997 to 20% in 2007 (p=0.009). In the 2007 material no specific age group could be identified with a lower immune profile than other age groups older than 3 years and there was a significant downward trend of invasive infections caused by Hib according to notification data for the period 1997-2008. Therefore, the conclusion is that presently there is no need for a booster dose of Hib vaccine in Sweden after primary vaccination but the situation should be carefully monitored.