High Levels Of Vaccination Coverage Research Articles

Assessing the impact of Australia's mass vaccination campaigns over the Delta and Omicron outbreaks.

The Australian Government implemented a national vaccination campaign against COVID-19 beginning February 22, 2021. The roll-out was criticised for being delayed relative to many high-income countries, but high levels of vaccination coverage were belatedly achieved. The large-scale Omicron outbreak in January 2022 resulted in a massive number of cases and deaths, although mortality would have been far higher if not for vigorous efforts to rapidly vaccinate the entire population. The impact of the vaccination coverage was assessed over this extended period. We considered NSW, as the Australian jurisdiction with the highest quality data for our purposes and which still reflected the national experience. Weekly death rates were derived among individuals aged 50+ with respect to vaccine status between August 8, 2021 and July 9, 2022. We evaluated deaths averted by the vaccination campaign by modelling alternative counterfactual scenarios based on a simple data-driven modelling methodology presented by Jia et al. (2023). Unvaccinated individuals had a 7.7-fold greater mortality rate than those who were fully vaccinated among people aged 50+, which rose to 11.2-fold in those who had received a booster dose. If NSW had fully vaccinated its ~2.9 million 50+ residents earlier (by July 28, 2021), only 440 of the total 3,495 observed 50+ deaths would have been averted. Up to July 9, 2022, the booster campaign prevented 1,860 deaths. In the absence of a vaccination campaign, ~21,250 COVID-19 50+ deaths (conservative estimate) could have been expected in NSW i.e., some 6 times the actual total. We also find the methodology of Jia et al. (2023) can sometimes significantly underestimate that actual number. The Australian vaccination campaign was successful in reducing mortality over 2022, relative to alternative hypothetical vaccination scenarios. The success was attributable to the Australian public's high levels of engagement with vaccination in the face of new SARS-COV-2 variants, and because high levels of vaccination coverage (full and booster) were achieved in the period shortly before the major Omicron outbreak of 2022.

A Decade of Experience in the use of 13-Valent Conjugated Polysaccharide Pneumococcal Vaccine in Russian Federation

Pneumococcal infection remains a significant global health problem, and vaccination is the main measure for its prevention. To date, the period of use of pneumococcal conjugated polysaccharide vaccines in Russia exceeds 14 years, and 13-valent conjugated polysaccharide pneumococcal vaccine (PCV13) - more than 10 years. During this time, extensive experience has been accumulated in the use of this type of vaccines, and many studies have been carried out to evaluate their effectiveness and safety.The purpose of this review is to summarize the experience of using PCV13 in Russian Federation with an assessment of its epidemiological and clinical effectiveness. A search was made for scientific publications devoted to the study of the epidemiological efficacy, the safety as well as cost-effectiveness of PCV13 use in Russian Federation. The review included original studies published in Russian journals. The results of the studies carried out indicate the efficacy and safety of PCV13 for both adults and children. The effectiveness of immunization of children at risk (premature, suffering from congenital pathology, having chronic diseases and often ill) was demonstrated, the need and safety of the timely start of vaccination (from 2 months of age) of newborns was shown, the possibility of its combination with immunization against other infections within the framework of the national vaccination schedule, the importance of following the recommended vaccination schedule in accordance with the age of the child. The effectiveness of vaccination of adults suffering from chronic diseases has been shown both in terms of preventing the aggravation of the course of the underlying pathology and reducing the risk of pneumonia. Positive experience has been gained in immunizing adults from occupational risk groups - medical workers, conscripts and persons exposed to a harmful production factor and having occupational lung diseases. The conducted studies have shown a high cost-effectiveness of PCV13 vaccination, however, with any changes in price and epidemiological parameters, it is necessary to clarify the economic feasibility of vaccination under the changed conditions. Taking into account the positive experience gained in immunization, it seems appropriate to further maintain a high level of vaccination coverage of the child population, expanding risk groups among the adult population subject to vaccination against pneumococcal infection within the framework of the National Immunization Schedule, taking into account its epidemiological, clinical and economic efficiency.

Vaccination coverage survey of children aged 1–3 years in Beijing, China, 2005–2021

BackgroundThe routine immunization program for children is a primary strategy and a core part of vaccination. Achieving and maintaining high level of vaccination coverage are important to reduce morbidity and mortality caused by vaccine-preventable diseases. In Beijing, annual coverage surveys have been conducted since 2005. It is necessary and possible to assess the level and trend of routine vaccination coverage of children in Beijing as well as the disruption of coronavirus disease 2019 (COVID-19) pandemic and provide the reference for the further improve the vaccination coverage. MethodsThe data of 61,521 children aged 1–3 years in the vaccination coverage surveys during 2005–2021 were analyzed by Beijing Center for Disease Control and Prevention. Descriptive epidemiological method was used to analyze the data and the difference of vaccination coverage within the time period. ResultsMore than 99 % of participants had immunization cards and electronic immunization records. The concordance rate of both records were also over 99 %. During 2011–2019, the rates of on-time and in-time vaccination of each routine vaccine reached 96 % or more and increased significantly (all P values <0.05), compared with that of 2005–2010. All rates of the investigated vaccine, except for Bacillus Calmette-Guérin vaccine (BCG) and the first dose of hepatitis B vaccine (HepB), decreased in 2020–2021 significantly (all P values <0.05). For the causes of failing to vaccinate on time, delayed vaccination accounted for 47.82 %. The top two vaccines to be missed were the first dose of hepatitis A vaccine and the 4th dose of diphtheria-tetanus-acellular pertussis vaccine, accounting for 21.41 % and 20.79 %, respectively. The main reason for zero-dose/drop-out vaccination was “Guardians regarded the immunization service time as inappropriate”, accounting for 72.27 %. ConclusionThe coverage level and service quality of routine immunization in Beijing were relatively high. However, as influenced by COVID-19 epidemics, both on-time and in-time vaccination rates decreased significantly, except for BCG and HepB. Under the background of COVID-19 pandemic, the keys to maintain high level of vaccination coverage include flexible immunization service time to ensure the guardians bringing their children for vaccination timely, and more attention from providers to the doses after children’s first birthday.

The effectiveness of medical personnel vaccination against hepatitis B

Medical personnel belong to the occupational risk group of hepatitis B virus (HBV) infection due to the increase of parenteral interventions and procedures using sophisticated equipment, constant contact with biological fluids of patients, the widespread use of antibiotics and cytostatics that have an immunosuppressive effect, etc. Insufficient objectivity in assessing the quality of hepatitis B (HBV) immunoprophylaxis only according to documentation may be associated with a violation of immunization regimens, the presence of chronic pathology in vaccinated, age-related immunodeficiency. Despite the effectiveness of HCV vaccination, the protective activity of specific humoral immunity (antibodies to HBsAg — anti-HBs) among vaccinated medical workers has not been sufficiently studied. The results of studying the intensity and duration of the immune response in 2075 employees of two large multidisciplinary hospitals vaccinated against HBV (average age 46.3 ± 10.1 years) are presented. A high level of vaccination coverage of medical personnel in hospitals No. 1 and No. 2 was established, amounting to 96.6 % and 97.2 %, and the level of collective immunity was equal to 1645.5±72.5 IU/l and 886±123.7 IU/l, respectively. The absence of cases of HBV in vaccinated individuals during immunoprophylaxis according to the standard scheme was noted. It seems advisable to use an individual approach to the tactics of revaccination when reducing the content of anti-HBs in the blood to low concentrations (10–100 IU / l), preventing them from falling below the protective level.

HPV-associated cervical cancer: Current status and prospects

Every year, 570,000 new cases of cervical cancer (CC) are diagnosed in the world, and 311,000 people die from this disease. CC is the fourth most common type of cancer and therefore the fourth leading cause of cancer death in women worldwide. Numerous data on the occurrence and development of cervical cancer indicate an association in most cases (up to 90 %) with human papillomaviruses (HPV) of high carcinogenic risk (HCR).CC prevention strategies are based on screening, and deaths from this oncopathology can be prevented through vaccination and treatment with early detection of the disease.In this review, much attention is paid to current issues of detection and prevention of HPV-associated pathologies, and cervical cancer in particular, aiming to summarize and analyze the latest international literature data on this issue. As a result of this study, it was shown that for countries implementing the National program of vaccination against HPV of high carcinogenic risk, a decrease in the incidence of both cervical pathologies of varying severity and other cancers associated with the HPV carriage was registered.While effective implementation of actual experience and future advances in human papillomavirus vaccine prophylaxis may make it possible for all countries to move to the high levels of vaccination coverage required to eliminate HPV-associated pathologies, the results also suggest that the path to complete cervical cancer elimination as a global public health problem can be extremely difficult due to a number of existing limitations.

The impact of the COVID-19 pandemic and the expansion of free vaccination policy on influenza vaccination coverage: An analysis of vaccination behavior in South Korea.

Annual vaccination for influenza is globally recommended for some prioritized groups due to its high morbidity and mortality. Until 2019, South Korea has provided free influenza vaccination to children aged ≤12, adults aged ≥65, and pregnant women to enhance vaccination coverage. In 2020, with the COVID-19 pandemic, free flu vaccination was temporarily broadened to adults aged 62-64 and children aged 13-18. We analyzed the trends in influenza vaccination coverages in South Korea and evaluated the impact of the COVID-19 pandemic and the expansion of the free vaccination policy on influenza vaccination coverage. We conducted a cross-sectional study with nationwide survey data from Korea National Health and Nutrition Examination Survey (KNHANES). We evaluated the trends in influenza vaccination coverages of target populations from 2010 to 2020. Influenza vaccination coverages of children aged 13-18, adults aged 62-64, and adults aged ≥65 were compared between 2019 and 2020. In total, 72,443 individuals were analyzed. From 2019 to 2020, with the expansion of free influenza vaccination and the COVID-19 pandemic, the vaccination coverage of children aged 13-18 increased from 27.8% to 43.5% (P<0.001) but that of people aged 62-64 showed insignificant change from 57.4% to 51.5% (P = 0.266). Furthermore, the vaccination coverage in adults aged ≥65 declined from 87.2% to 79.1% (P<0.001). In 2020, along with COVID-19 outbreaks, a decline of influenza vaccination coverage in older adults was observed regardless of free immunizations. It is likely due to behavioral changes to reduce the risk of COVID-19 transmission. This is supported by a greater reduction of influenza vaccination coverage in regions with higher COVID-19 outbreaks, as well as by South Korea's high medical accessibility and highly congested medical facilities. To sustain a high level of vaccination coverage of high-risk population during epidemics, additional efforts beyond free vaccination policies should be implemented.

Защитное действие вакцинации против кори, краснухи и паротита в отношении COVID-19

Based on the results of studies, it has been shown that vaccination against measles, mumps rubella (MMR) can prevent mortality and severe forms of COVID-19 in vulnerable groups of the population. It was found that the high level of vaccination coverage against MMR was inversely correlated with the mortality rate from COVID-19 – the higher the vaccination rate against MMR, the lower the number of mortality from COVID-19 and severe forms. The effect of MMR immunization on the incidence of COVID-19 is explained by correspondence between COVID-19 virus proteins and MMR viruses. The results of studies conducted in various countries and have shown that the effect of protection against COVID-19 is based on the homology of individual sequences of SARS-CoV-2 coronavirus proteins with MMR viruses. The similarity of the SARS-COV-2 virus with the MMR viruses allows the MMR vaccine to be used for mass use for non-specific protection against COVID-19. In order to increase the effectiveness of vaccination against MMR in people with impaired health, the use of immunomodulatory drugs is recommended. This approach not only increases specific immunity against vaccinated infections, but also enhances nonspecific protection against COVID-19. Key words: SARS-CoV-2 virus, live vaccines, COVID-19 disease, immunization, measles, rubella, mumps

Quality analysis of a combined domestic vaccine for the prevention of measles, rubella and mumps

The need to maintain a high level of vaccination coverage against measles, rubella and mumps in conditions of an increased risk of outbreaks of infections due to violations of vaccination tactics associated with the pandemic of coronavirus infection and due to the unfavorable epidemic situation in neighboring countries determines the advisability of using a combined vaccine for the simultaneous prevention of these three socially significant infections. to analyze the quality of commercial series of a new domestic combined cultured live vaccine against measles, rubella and mumps (MRM) throughout the entire time of its manufacturing according to all specification indicators in regulatory documentation (RD). The object of the study was the combined cultured live vaccine against measles, rubella and mumps. The analysis of the quality of the drug was carried out according to 86 consolidated production protocols of manufactured series, as well as according to the results of control of these series in the Testing Center for Quality Expertise of the Federal State Budgetary Institution NCESMP of the Ministry of Health of the Russian Federation. It is shown that the quality of the combined drug for the prevention of measles, rubella and mumps corresponds to the RD in all studied indicators. The drug does not contain an antibiotic. Bovine serum albumin, which is a technological impurity, is detected in quantities more than 5 times lower than the established norm. A comparison of the specific activity of the viral components of new combined domestic vaccine and the components of the bivalent vaccine against measles and mumps produced by the company in 20192021 showed that the spread of the activity values of the viral components in the new drug and in the series of mumps-measles vaccine was minimal, which allowed us to make a conclusion about the stability of the production technology. The quality of the new domestic combined vaccine for the prevention of measles, rubella and mumps meets WHO requirements. The results of the conducted studies indicate the stability of production and the standard quality of the drug. The use of a combined vaccine against three significant infections will ensure the necessary level of vaccination coverage in the population. Information about the results of studies can help reduce the number of vaccination refusal.

Impact of disruptions to routine vaccination programs, quantifying burden of measles, and mapping targeted supplementary immunization activities

Measles is a highly transmissible disease that requires high levels of vaccination coverage for control and elimination. Areas that are unable to achieve and maintain high coverage levels are at risk for measles outbreaks resulting in increased morbidity and mortality. Public health emergencies, such as the current COVID-19 pandemic, pose a threat to the functioning of health systems by disrupting immunization services which can derail measles vaccination efforts. Efforts to bridge coverage gaps in immunization include the rapid return to fully functioning services as well as deploying supplementary immunization activities (SIAs), which are additional vaccination campaigns intended to catch-up children who have missed routine services. However, SIAs, which to date tend to be national efforts, can be difficult to mobilize quickly, resource-intensive, and even more challenging to deploy during a public health crisis. By mapping expected burden of measles, more effective SIAs that are setting-specific and resource-efficient can be planned and mobilized. Using a spatial transmission model of measles dynamics, we projected and estimated the expected burden of national and local measles outbreaks in Zambia with the current COVID-19 pandemic as a framework to inform disruptions to routine vaccination. We characterize the impact of disruptions to routine immunization services on measles incidence, map expected case burden, and explore SIA strategies to mitigate measles outbreaks. We find that disruptions lasting six months or longer as well as having low MCV1 coverage prior to disruptions resulted in an observable increase of measles cases across provinces. Targeting provinces at higher risk of measles outbreaks for SIAs is an effective strategy to curb measles virus incidence following disruptions to routine immunization services.

Susceptibility to Resurgent COVID-19 Outbreaks Following Vaccine Rollouts: A Modeling Study.

Using the recently proposed Susceptible–Asymptomatic–Infected–Vaccinated–Removed (SAIVR) model, we study the impact of key factors affecting COVID-19 vaccine rollout effectiveness and the susceptibility to resurgent epidemics. The SAIVR model expands the widely used Susceptible–Infectious–Removed (SIR) model for describing epidemics by adding compartments to include the asymptomatic infected (A) and the vaccinated (V) populations. We solve the model numerically to make predictions on the susceptibility to resurgent COVID-19 epidemics depending on initial vaccination coverage, importation loads, continuing vaccination, and more contagious SARS-CoV-2 variants, under persistent immunity and immunity waning conditions. The parameters of the model represent reported epidemiological characteristics of the SARS-CoV-2 virus such as the disease spread in countries with high levels of vaccination coverage. Our findings help explain how the combined effects of different vaccination coverage levels and waning immunity lead to distinct patterns of resurgent COVID-19 epidemics (either surges or endemic), which are observed in countries that implemented different COVID-19 health policies and achieved different vaccinated population plateaus after the vaccine rollouts in the first half of 2021.

Planning and Organization of the COVID-19 Vaccination Campaign: An Overview of Eight European Countries.

The initial progress of the COVID-19 vaccination campaign worldwide depended on several aspects, including programmatic/practical issues. This paper focused on the planning and organization of COVID-19 vaccination campaigns in eight European countries (Sweden, Denmark, Romania, Hungary, Italy, Spain, Germany, and France), from the launch to August 2021. Information on the planning of the vaccination campaign (release and update of a national immunization plan, types of vaccines being used and their limitations/suspensions) and its organization (vaccination target groups, possibility of citizens’ choice, vaccination workforce and settings, vaccines procurement) were obtained through desk research of international and national reports, plans, and websites. Eventually, data on vaccination coverage were drawn from Our world in data and analyzed through join point regression. The eight countries showed differences in groups prioritization, limitations/suspensions of use of specific vaccines, citizens’ possibility to choose vaccines, and vaccination workforce involved. These issues could have contributed to the different progress towards high levels of vaccination coverage. In respect to vaccination coverage, Romania reached much lower levels than other countries. Further comparative research is needed in order to identify best practices in vaccination campaign that could be useful for the next phases of the COVID-19 pandemic, and be better prepared for future potential pandemic.

COVID-19 vaccination in the Gaza Strip: a cross-sectional study of vaccine coverage, hesitancy, and associated risk factors among community members and healthcare workers

BackgroundThe Gaza Strip, like other settings of complex humanitarian emergencies, faces immense challenges in vaccinating its population against COVID-19. This study was conducted in October 2021 among Gaza’s adult population and healthcare workers (HCWs). The primary aim was to estimate two indicators, coverage of COVID-19 vaccination and the prevalence of vaccine hesitancy. The secondary aim was to evaluate the two indicators’ associations with globally identified risk factors.MethodsA cross-sectional study was conducted using a population-based survey of adults and a purposive survey of HCWs in Gaza. A multi-stage sampling design was used for the population survey component. For the HCW component, five health facilities were purposively selected as entry points; HCWs in the facilities holding clinical or other specialized positions were approached to participate in the survey. Data were summarized as univariable descriptive statistics with unweighted and weighted point estimates. Logistic regression was used to evaluate associations of risk factors with vaccination status and vaccine hesitancy.ResultsA total of 1075 individuals were surveyed, of whom 906 were community members and 169 were HCWs. Population-weighted vaccine coverage was estimated to be 49.08% (95% CI 43.10–55.08). 89.35% of HCWs were vaccinated. Population-weighted vaccine hesitancy was estimated to be 34.08% (95% CI 28.14–40.56) in the overall population and 67.24% (95% CI 49.04–81.41) among the unvaccinated sub-group. In logistic regression vaccination was independently associated with male sex (aOR 1.88, p = 0.006, 95% CI 1.20–2.95), older age (40+ vs. 18–39 age group) (aOR 1.92, p < 0.001, 95% CI 1.73–2.13), higher education (aOR 2.19, p < 0.001, 95% CI 1.51–3.17), and confidence in the safety of the vaccine (aOR 13.8, p < 0.001, 95% CI 10.1–18.8). Risk factors for hesitancy were similar to those identified for vaccination status, however hesitant individuals were somewhat more likely to obtain vaccine information from family members (aOR 1.29, p = 0.051, 95% CI 1.00–1.67) and less likely to trust healthcare providers (aOR 0.58, p < 0.001, 95% CI 0.49–0.68).ConclusionsThe continued emergence of SARS-CoV-2 variants reinforces the importance of achieving high levels of vaccination coverage globally—a difficult undertaking in Gaza. This study estimated half of Gaza’s adult population received at least one dose of any COVID-19 vaccine by October 2021, and the majority of unvaccinated individuals were hesitant. Disparities in vaccination across the territory’s demographic groups underscore the need for targeted outreach to these populations and messaging through community-based channels to permeate social networks of the unvaccinated.

Mapping BCG vaccination coverage in Ethiopia between 2000 and 2019

IntroductionThe Bacille-Calmette–Guerin (BCG) vaccination remains the primary strategy to prevent severe disseminated TB in young children, particularly in high TB-burden countries such as Ethiopia. Accurate knowledge of vaccination coverage in small geographical areas is critically important to developing targeted immunization campaigns. Thus, this study aimed to investigate the spatiotemporal distributions and ecological level determinants of BCG vaccination coverage in Ethiopia.MethodBacille-Calmette–Guerin immunization coverage and geographical information data were obtained from five different Demographic and Health Surveys, conducted in Ethiopia between 2000 and 2019. Data for independent variables were obtained from publicly available sources. Bayesian geostatistical models were used to predict the spatial distribution of BCG vaccination coverage in Ethiopia.ResultThe overall national BCG vaccination coverage between 2000 and 2019 was 65.5%. The BCG vaccine coverage was 53.5% in 2000, 56.9% in 2005, 64.4% in 2011, 79.6% in 2016, and 79.0% in 2019. BCG vaccination coverage increased by 47.6% in Ethiopia from 2000 to 2019, but substantial geographical inequalities in BCG coverage remained at sub-national and local levels. High vaccination coverage was observed in northern, western, and central parts of Ethiopia. Climatic and demographic factors such as temperature, altitude, and population density were positively associated with BCG vaccination coverage. Whereas, healthcare access factors such as distance to health facilities and travel time to the nearest cities were negatively associated with BCG vaccine coverage in Ethiopia.ConclusionDespite substantial progress in national BCG vaccination coverage, marked spatial variation in BCG coverage persists throughout the country at sub-national and local levels. Healthcare access and climatic and demographic factors determined the spatial distribution of BCG vaccination coverage. Maintaining a high level of vaccination coverage across geographical areas is important to prevent TB in Ethiopia.

Outcomes of SARS-CoV-2 omicron infection in residents of long-term care facilities in England (VIVALDI): a prospective, cohort study

BackgroundThe SARS-CoV-2 omicron variant (B.1.1.529) is highly transmissible, but disease severity appears to be reduced compared with previous variants such as alpha and delta. We investigated the risk of severe outcomes following infection in residents of long-term care facilities.MethodsWe did a prospective cohort study in residents of long-term care facilities in England who were tested regularly for SARS-CoV-2 between Sept 1, 2021, and Feb 1, 2022, and who were participants of the VIVALDI study. Residents were eligible for inclusion if they had a positive PCR or lateral flow device test during the study period, which could be linked to a National Health Service (NHS) number, enabling linkage to hospital admissions and mortality datasets. PCR or lateral flow device test results were linked to national hospital admission and mortality records using the NHS-number-based pseudo-identifier. We compared the risk of hospital admission (within 14 days following a positive SARS-CoV-2 test) or death (within 28 days) in residents who had tested positive for SARS-CoV-2 in the period shortly before omicron emerged (delta-dominant) and in the omicron-dominant period, adjusting for age, sex, primary vaccine course, past infection, and booster vaccination. Variants were confirmed by sequencing or spike-gene status in a subset of samples.Results795 233 tests were done in 333 long-term care facilities, of which 159 084 (20·0%) could not be linked to a pseudo-identifier and 138 012 (17·4%) were done in residents. Eight residents had two episodes of infection (>28 days apart) and in these cases the second episode was excluded from the analysis. 2264 residents in 259 long-term care facilities (median age 84·5 years, IQR 77·9–90·0) were diagnosed with SARS-CoV-2, of whom 253 (11·2%) had a previous infection and 1468 (64·8%) had received a booster vaccination. About a third of participants were male. Risk of hospital admissions was markedly lower in the 1864 residents infected in the omicron-period (4·51%, 95% CI 3·65–5·55) than in the 400 residents infected in the pre-omicron period (10·50%, 7·87–13·94), as was risk of death (5·48% [4·52–6·64] vs 10·75% [8·09–14·22]). Adjusted hazard ratios (aHR) also indicated a reduction in hospital admissions (0·64, 95% CI 0·41–1·00; p=0·051) and mortality (aHR 0·68, 0·44–1·04; p=0·076) in the omicron versus the pre-omicron period. Findings were similar in residents with a confirmed variant.InterpretationObserved reduced severity of the omicron variant compared with previous variants suggests that the wave of omicron infections is unlikely to lead to a major surge in severe disease in long-term care facility populations with high levels of vaccine coverage or natural immunity. Continued surveillance in this vulnerable population is important to protect residents from infection and monitor the public health effect of emerging variants.FundingUK Department of Health and Social Care.

Основні питання вакцинації дітей та підлітків проти COVID-19

The main principles of specific immunoprophylaxis of COVID-19 in children and adolescents were determined based on the accumulated scientific data. It was established that only two vaccines, Pfizer-BioNTech (BNT162b2) «Comirnaty» and Moderna mRNA-1273 «Spikevax» were approved by the WHO for emergency use in children and only the first of them was approved for use in Ukraine. Both vaccines have a proven safety and efficacy profile according to the results of clinical trials. The current analysis of side effects associated with Pfizer-BioNTech (BNT162b2) "Comirnaty" and Moderna mRNA-1273 "Spikevax" vaccination indicates a favorable clinical course of local, systemic reactions and myocarditis following a vaccination with regression of symptoms in all patients. The risk of the multisystem inflammatory syndrome in children following acute infection, the potential for other sequelae of SARS-CoV-2 infection, the risk of severe disease in children with underlying medical conditions, remain compelling reasons for vaccination of children and outweigh possible risks of side effects associated with vaccination. In the context of the global shortage of vaccines in the world, immunization programs should focus on groups of highest risk of hospitalizations and deaths, according to the Prioritization Roadmap. Children vaccination against COVID-19 with risk factors, comorbidities, immunodeficiency is a priority. Before vaccinating children and adolescents at low risk of serious disease, children from high-risk groups should be actively identified and vaccinated, justifying the importance of their vaccination. Despite the widespread introduction of vaccination, appropriate preventive measures for fighting COVID-19 should be taken, including physical distancing, frequent handwashing, wearing masks. It is extremely important to maintain a high level of vaccination coverage against other infectious diseases and not to delay the planned vaccination of children. No conflict of interests was declared by the authors. Key words: vaccination, COVID-19, children.

Evolution of Responses to COVID-19 and Epidemiological Characteristics in South Korea.

The characteristics of COVID-19 have evolved at an accelerated rate over the last two years since the first SARS-CoV-2 case was discovered in December 2019. This evolution is due to the complex interplay among virus, humans, vaccines, and environments, which makes the elucidation of the clinical and epidemiological characteristics of COVID-19 essential to assess ongoing policy responses. In this study, we carry out an extensive retrospective analysis on infection clusters of COVID-19 in South Korea from January 2020 to September 2021 and uncover important clinical and social factors associated with age and regional patterns through the sophisticated large-scale epidemiological investigation using the data provided by the Korea Disease Control and Prevention Agency (KDCA). Epidemiological data of COVID-19 include daily confirmed cases, gender, age, city of residence, date of symptom onset, date of diagnosis, and route of infection. We divide the time span into six major periods based on the characteristics of COVID-19 according to various events such as the rise of new variants, vaccine rollout, change of social distancing levels, and other intervention measures. We explore key features of COVID-19 such as the relationship among unlinked, asymptomatic, and confirmed cases, serial intervals, infector–infectee interactions, and age/region-specific variations. Our results highlight the significant impact of temporal evolution of interventions implemented in South Korea on the characteristics of COVID-19 transmission, in particular, that of a high level of vaccination coverage in the senior-aged group on the dramatic reduction of confirmed cases.

A BEHAVIORAL CHANGE MODEL TO ASSESS VACCINATION-INDUCED RELAXATION OF SOCIAL DISTANCING DURING AN EPIDEMIC

The success of mass vaccination campaigns may be jeopardized by human risky behaviors. For example, high level of vaccination coverage may induce early relaxation of social distancing. In this paper, we focus on the mutual influence between the decline in prevalence, due to the rise in the overall immunization coverage, and the consequent decrease in the compliance to social distancing measures. We consider an epidemic model where both the vaccination rate and the disease transmission rate are influenced by human behavior, which in turn depends on the current and past information about the spread of the disease. We highlight the impact of the information-related parameters on the transient and asymptotic behavior of the system that is on the early stage of the epidemic and its final outcome. Among the main results, we evidence that sustained oscillations may be triggered by the behavioral memory in the prevalence-dependent vaccination rate. However, the relaxation of social distancing may induce a switch from a cyclic regime to damped oscillations.

Review of Vaccination Coverage Assessed by the Kindergarten Immunization Survey in Delaware

Vaccinations are the primary means used in public health to avert morbidity and mortality from preventable diseases and are crucial for reducing the development of infectious disease outbreaks. To ensure a high level of vaccine coverage, the State of Delaware requires that all children receive specific vaccinations against dangerous pathogens prior to enrolling in a school. By requiring all children to be vaccinated against certain diseases, individuals who have religious or medical exemptions for receiving vaccines are also protected. The percentage of vaccine coverage among kindergarten students is surveyed annually by the Delaware Immunization Program and the Centers for Disease Control and Prevention (CDC), via random sampling. Data acquired during the period from 2016 to 2021 shows that vaccine coverages have a declining trend, which may be due in part to the COVID-19 pandemic and increased vaccine hesitancy. Reviewing these data allows for a more robust understanding of disease trends and provides an indication as to where resources may need to be allocated to address lagging vaccine rates.

Mitigating the SARS-CoV-2 Delta disease burden in Australia by non-pharmaceutical interventions and vaccinating children: a modelling analysis

BackgroundIn countries with high COVID-19 vaccination rates the SARS-CoV-2 Delta variant resulted in rapidly increasing case numbers. This study evaluated the use of non-pharmaceutical interventions (NPIs) coupled with alternative vaccination strategies to determine feasible Delta mitigation strategies for Australia. We aimed to understand the potential effectiveness of high vaccine coverage levels together with NPI physical distancing activation and to establish the benefit of adding children and adolescents to the vaccination program. Border closure limited SARS-CoV-2 transmission in Australia; however, slow vaccination uptake resulted in Delta outbreaks in the two largest cities and may continue as international travel increases.MethodsAn agent-based model was used to evaluate the potential reduction in the COVID-19 health burden resulting from alternative vaccination strategies. We assumed immunity was derived from vaccination with the BNT162b2 Pfizer BioNTech vaccine. Two age-specific vaccination strategies were evaluated, ages 5 and above, and 12 and above, and the health burden determined under alternative vaccine coverages, with/without activation of NPIs. Age-specific infections generated by the model, together with recent UK data, permitted reductions in the health burden to be quantified.ResultsCases, hospitalisations and deaths are shown to reduce by (i) increasing coverage to include children aged 5 to 11 years, (ii) activating moderate NPI measures and/or (iii) increasing coverage levels above 80%. At 80% coverage, vaccinating ages 12 and above without NPIs is predicted to result in 1095 additional hospitalisations per million population; adding ages 5 and above reduces this to 996 per million population. Activating moderate NPIs reduces hospitalisations to 611 for ages 12 and over, and 382 per million for ages 5 and above. Alternatively, increasing coverage to 90% for those aged 12 and above is estimated to reduce hospitalisations to 616. Combining all three measures is shown to reduce cases to 158, hospitalisations to 1 and deaths to zero, per million population.ConclusionsDelta variant outbreaks may be managed by vaccine coverage rates higher than 80% and activation of moderate NPI measures, preventing healthcare facilities from being overwhelmed. If 90% coverage cannot be achieved, including young children and adolescents in the vaccination program coupled with activation of moderate NPIs appears necessary to suppress future COVID-19 Delta-like transmission and prevent intensive care unit surge capacity from being exceeded.

Multi-Level Monitoring of Vaccination Adherence of Various Population Groups in the Context of the COVID-19 Pandemic: Problematic Issues

Relevance. Despite significant progress in the prevention of many infectious diseases, a number of organizational issues remain in the area of special attention. One of them is to ensure the timeliness and completeness of vaccination coverage in the decreed age groups, which is possible only with a high level of public commitment to vaccination. During the pandemic of the new coronavirus infection (COVID-19), achieving a high level of vaccination coverage of the National Calendar of Preventive vaccinations is of particular relevance. Aim. Using state-of-the-art online resources, assess population vaccination adherence to develop effective communication risk management technologies for immunoprophylaxis in the COVID-19 pandemic. Materials and methods. To assess the commitment of various population groups and professional contingents of a large industrial city to vaccine prevention, a survey of 965 parents was conducted at the initial stage, and subsequently a survey of 2,632 employees of medical organizations, including 1,422 people in the period before the COVID - 19 pandemic, 572 people in the «first wave» of the pandemic and 638 people in the «second wave». Instagram Facebook, Instagram, and VKontakte social networks were used to quickly obtain the necessary information (Google forms, corporate e-mails, WhatsApp, Telegram messengers, etc.). The work uses epidemiological, sociological and statistical methods of research. Results and discussion. When assessing the attitude of parents to vaccination, it was found that 78.8% of respondents were positive about vaccinations, 14.6% doubted their effectiveness and safety, and 6.6% denied their need. The main source of information that forms the attitude to vaccinations of parents was the opinion of medical professionals. In a survey of 1,422 employees, 190 people (13.3%) were identified, mainly from among the trained specialists, who themselves had a negative attitude to vaccination. When assessing the commitment of employees of medical organizations to the vaccination of a new coronavirus infection, the attitude to vaccination was ambiguous, especially in the group of secondary medical personnel and female employees of non-medical specialties, who are a potential risk group for forming a negative attitude to vaccinations and can act as «opinion leaders» on this issue for other categories of the population. Insufficient adherence to COVID-19 vaccine prevention has also been observed in other countries among various population groups, which is a serious problem on a global scale, hindering the fight against the pandemic of a new disease, which requires corrective measures. Conclusion. In this study, using modern online resources, a rapid assessment of the vaccination adherence of various population groups (parents and medical professionals) was carried out. It is shown that the use of modern technologies and software tools makes it possible to analyze a large array of data to solve problems of overcoming communication risks. The results obtained point to the need for prompt corrective measures in terms of the introduction of educational programs to increase adherence to vaccination, especially in groups at potential risk of the disease, including medical professionals, which is a priority for health care in all countries.