Vaccination Schedule under Conditions of Limited Vaccine Production Rate

The paper is devoted to optimal vaccination scheduling during a pandemic to minimize the probability of infection. The recent COVID-19 pandemic showed that the international community is not properly prepared to manage a crisis of this scale. Just after the vaccines had been approved by medical agencies, the policymakers needed to decide on the distribution strategy. To successfully fight the pandemic, the key is to find the equilibrium between the vaccine distribution schedule and the available supplies caused by limited production capacity. This is why society needs to be divided into stratified groups whose access to vaccines is prioritized. Herein, we present the problem of distributing protective actions (i.e., vaccines) and formulate two mixed-integer programs to solve it. The problem of distributing protective actions (PDPA) aims at finding an optimal schedule for a given set of social groups with a constant probability of infection. The problem of distributing protective actions with a herd immunity threshold (PDPAHIT) also includes a variable probability of infection, i.e., the situation when herd immunity is obtained. The results of computational experiments are reported and the potential of the models is illustrated with examples.

Cases of Acute Flaccid Paralysis Associated with Coxsackievirus A2: Findings of a 20-Year Surveillance in the Russian Federation

Surveillance for acute flaccid paralysis syndrome (AFP) in children under 15 is the backbone of the Global Polio Eradication Initiative. Laboratory examination of stool samples from AFP cases allows the detection of, along with polioviruses, a variety of non-polio enteroviruses (NPEV). The etiological significance of these viruses in the occurrence of AFP cases has been definitively established only for enteroviruses A71 and D68. Enterovirus Coxsackie A2 (CVA2) is most often associated with vesicular pharyngitis and hand, foot and mouth disease. Among 7280 AFP cases registered in Russia over 20 years (2001–2020), CVA2 was isolated only from five cases. However, these included three children aged 3 to 4 years, without overt immune deficiency, immunized with 4–5 doses of poliovirus vaccine in accordance with the National Vaccination Schedule. The disease resulted in persistent residual paralysis. Clinical and laboratory data corresponded to poliomyelitis developing during poliovirus infection. These findings are compatible with CVA2 being the cause of AFP. Molecular analysis of CVA2 from these patients and a number of AFP cases in other countries did not reveal association with a specific phylogenetic group, suggesting that virus genetics is unlikely to explain the pathogenic profile. The overall results highlight the value of AFP surveillance not just for polio control but for studies of uncommon AFP agents.

Effects of Loigolactobacillus coryniformis K8 CECT 5711 on the Immune Response of Elderly Subjects to COVID-19 Vaccination: A Randomized Controlled Trial

Elderly people are particularly vulnerable to COVID-19, with a high risk of developing severe disease and a reduced immune response to the COVID-19 vaccine. A randomized, placebo-controlled, double-blind trial to assess the effect of the consumption of the probiotic Loigolactobacillus coryniformis K8 CECT 5711 on the immune response generated by the COVID-19 vaccine in an elderly population was performed. Two hundred nursing home residents >60 yrs that had not COVID-19 were randomized to receive L. coryniformis K8 or a placebo daily for 3 months. All volunteers received a complete vaccination schedule of a mRNA vaccine, starting the intervention ten days after the first dose. Specific IgG and IgA antibody levels were analyzed 56 days after the end of the immunization process. No differences between the groups were observed in the antibody levels. During the intervention, 19 subjects had COVID-19 (11 receiving K8 vs. 8 receiving placebo, p = 0.457). Subgroup analysis in these patients showed that levels of IgG were significantly higher in those receiving K8 compared to placebo (p = 0.038). Among subjects >85 yrs that did not get COVID-19, administration of K8 tended to increase the IgA levels (p = 0.082). The administration of K8 may enhance the specific immune response against COVID-19 and may improve the COVID-19 vaccine-specific responses in elderly populations.

Narrowing gap in regional and age-specific excess mortality in the first year and a half of COVID-19 in Hungary

In the first year and a half of the pandemic, the excess mortality in Hungary was 28,400, which was 1,700 lower than the official statistics on COVID-19 deaths. This discrepancy can be partly explained by protective measures instated during the COVID-19 pandemic that decreased the intensity of the seasonal flu outbreak, which caused on average 3,000 deaths per year. Compared to the second wave of the COVID-19 pandemic, the third wave showed a reduction in the differences in excess mortality between age groups and regions. The excess mortality rate for people aged 75+ fell significantly in the third wave, partly due to the vaccination schedule and the absence of a normal flu season. For people aged 40-77, the excess mortality rate rose slightly in the third wave. Between regions, excess mortality was highest in Northern Hungary and Western Transdanubia, and much lower in Central Hungary, where the capital is located. The excess mortality rate for men was almost twice as high as that for women in almost all age groups.

Scaling the Children Immunization App (CIMA) to Support Child Refugees and Parents in the Time of the COVID-19 Pandemic: A Social Capital Approach to Scale a Smartphone Application in Zaatari Camp, Jordan

Background Children vaccination is a key intervention for their survival, especially among refugees. Yet, children vaccination registration is done manually in refugees camps and there is no possibility to send reminders to parents to come back on time. We aimed to boost the parental registration of children’s vaccination records on a Children Immunization app (CIMA) while also availing the parents with useful parenting skills under COVID-19-related stress. Methods We incorporated United Nations Office on Drugs and Crime (UNODC) Parenting Skills under COVID-19 information material, through CIMA in Arabic and English languages. We recruited 1100 children in February–March 2021, through a community health promotion dissemination approach. A team of two nurses from the local population and two volunteers (one trained nurse and one trained social worker), from the camp, was formed. They promoted the CIMA app at two clinics and through households visits in Zaatari refugee camp. Qualitative data on impressions and observations of the interactions with the Zaatari camp community were also collected. Results A total of 1100 children, up to 15 months of age, eligible for vaccination were enrolled in CIMA, whereby the staff explained the content of the app in terms of vaccination schedule, health promotion materials for vaccination and parenting skills to their caregivers. During the household visits, the volunteers identified a total of 70 children that have incomplete history of vaccination records (n = 42/70 girls, 60%). Also, opportunities and challenges for scaling the app were documented. Conclusion The scaling of CIMA as an innovative means of dissemination of risk and health information in challenging context such as refugee camps was feasible. In the context of vaccination needs for children, in refugee settings, such a need is more eminent, particularly in the context of COVID-19.

Attitudes of Poles towards the COVID-19 Vaccine Booster Dose: An Online Survey in Poland

Introduction: COVID-19 vaccination has now become the most effective way to combat the pandemic, but there is a gradual decline in the protection that it offers over time. Therefore, the Food and Drug Administration (FDA) and EMA now recommend the use of the so-called booster dose, especially in at-risk groups. The purpose of the study was to assess the attitudes of Poles towards the recommendation to receive a booster dose of the COVID-19 vaccine and to evaluate the main reasons for refusing or delaying the decision. Material and methods: The study was based on a proprietary questionnaire distributed via the Internet. There were 1598 respondents, 54 of which did not consent to participate in the survey and/or did not complete the vaccination against SARS-CoV-2. As a result, 1528 surveys were included in the final analysis. The vast majority of the respondents, namely 1275 (83.4%), were female, and 772 (50.5%) were residents of cities with a population of over 250,000. Results: Out of all respondents, 38 (2.5%) had already received the COVID-19 vaccine booster dose and 1031 (67.4%) would like to receive it as soon as possible. Forty-five (2.9%) respondents reported that they were completely unwilling to take the booster dose. The occurrence of adverse events after primary vaccination were reported by 79.9% of the survey participants. The most common reasons why the respondents refused to be vaccinated are lack of confidence in the effectiveness of the booster dose and the occurrence of adverse events in them or their loved ones. Age, gender, residence, or relationship status were not shown to affect attitudes towards the expansion of the basic vaccination schedule. Conclusions: One in three respondents plans to delay or refrain from taking the COVID-19 vaccine booster dose. The main reason for refusal to be vaccinated is the belief that the previous vaccination provides sufficient protection.

Factors associated with the incomplete opportune vaccination schedule up to 12 months of age, Rondonópolis, Mato Grosso

Objective: To analyze factors associated with the incomplete timely vaccination schedule up to 12 months of age, in children born in 2015, in the municipality of Rondonópolis, Mato Grosso. Methods: Population survey, August/2017 to February/2018, which used the method proposed by the World Health Organization to collect information about routine vaccination. For analysis of the associated factors, the recommendations of the National Immunization Program of the Ministry of Health were considered. Univariate analysis was performed, and the factors associated with p<0.20 entered in the multiple analysis, with hierarchical entry of individual variables and contextual indicator of concentration of the income extremes. Results: The incomplete timely vaccination schedule up to 12 months was 82.03% (95%CI 78.41–86.63). In the final model, the following remained independently associated: having one or more siblings at home (OR 3.18; 95%CI 1.75–5.76) and not receiving a visit from a community health worker in the last 30 days (OR 1.93; 95%CI 1.04–3.57). Conclusions: It is necessary to implement an active search for children with vaccination delay in relation to the recommended interval for each vaccine, in addition to the need to strengthen the link of the family health strategy and child caregivers.

Predicting the impact of COVID-19 vaccination campaigns - a flexible age-dependent, spatially-stratified predictive model, accounting for multiple viral variants and vaccines

Background: After COVID-19 vaccines received approval, vaccination campaigns were launched worldwide. Initially, these were characterized by a shortage of vaccine supply, and specific risk groups were prioritized. Once supply was guaranteed and vaccination coverage saturated, the focus shifted from risk groups to anti-vaxxers, the underaged population, and regions of low coverage. At the same time, hopes to reach herd immunity by vaccination campaigns were put into perspective by the emergence and spread of more contagious and aggressive viral variants. Particularly, concerns were raised that not all vaccines protect against the new-emerging variants. Methods and findings: A model designed to predict the effect of vaccination campaigns on the spread of viral variants is introduced. The model is a comprehensive extension of the model underlying the pandemic preparedness tool CovidSim 2.0 (http://covidsim.eu/). The model is age and spatially stratified, incorporates a finite (but arbitrary) number of different viral variants, and incorporates different vaccine products. The vaccines are allowed to differ in their vaccination schedule, vaccination rates, the onset of vaccination campaigns, and their effectiveness. These factors are also age and/or location dependent. Moreover, the effectiveness and the immunizing effect of vaccines are assumed to depend on the interaction of a given vaccine and viral variant. Importantly, vaccines are not assumed to immunize perfectly. Individuals can be immunized completely, only partially, or fail to be immunized against one or many viral variants. Not all individuals in the population are vaccinable. The model is formulated as a high-dimensional system of differential equations, which is implemented efficiently in the programming language Julia. As an example, the model was parameterized to reflect the epidemic situation in Germany until November 2021 and predicted the future dynamics of the epidemic under different interventions. In particular, without tightening contact reductions, a strong epidemic wave is predicted. At the current state, mandatory vaccination would be too late to have a strong effect on reducing the number of infections. However, it would reduce mortality. An emergency brake, i.e., an incidence-based stepwise lockdown would be efficient to reduce the number of infections and mortality. Furthermore, to specifically account for mobility between regions, the model was applied to two German provinces of particular interest: Saxony, which currently has the lowest vaccine rollout in Germany and high incidence, and Schleswig-Holstein, which has high vaccine rollout and low incidence. Conclusions: A highly sophisticated and flexible but easy-to-parameterize model for the ongoing COVID-19 pandemic is introduced. The model is capable of providing useful predictions for the COVID-19 pandemic, and hence provides a relevant tool for epidemic decision-making. The model can be adjusted to any country, to derive the demand for hospital and ICU capacities as well as economic collateral damages.

Determination of diphtheria risk indicators based on the study of antidiphtheria immunity in the population of Dnipropetrovsk region

Background. Vaccination is the most effective part of primary prevention. Serological monitoring of infectious diseases covered by national immunization programs is very important as it provides up-to-date information on the burden of the infection and the immunological status of the population. The study was aimed to present an analysis of epidemiological monitoring of the protection against diphtheria of the population, to show the generalized epidemiological situation regarding diphtheria, and to determine the risk of diphtheria among the population of Dnipropetrovsk region. Materials and methods. Epidemiological analysis of diphtheria immunity (2017–2019) was performed based on the results of enzyme-linked immunosorbent assay of IgG antibodies levels against diphtheria toxin in 271 residents of Dnipropetrovsk region. Results. Analysis of the results revealed that only 30.6 % (n = 83) of the population have levels of antitoxic antibodies of 1.0 IU/ml or more, which provides sufficient protection against diphtheria in the next 5–7 years of life. At that time, the majority of the population (69.4 %) needs immediate one-time booster vaccination (n = 134; 49.5 %) or immediate basic vaccination (n = 54; 19.9 %) due to low levels of antitoxic diphtheria antibodies. In the age group 8–15 years, 65.9 % (n = 62) of patients require immediate basic or booster vaccination, which indicates that children of this age do not have basic immunological protection due to violations of the vaccination schedule or its absence. In the group aged 27 years and older, 79.1 % (n = 72) of the subjects do not have protective levels of anti-diphtheria antibodies, which indicates a lack of actual protection against diphtheria. Conclusions. The results indicate insufficient protection of the population against diphtheria. In this regard, the development of strategic measures for mass immunoprophylaxis of diphtheria both in children and adults is relevant. The country should conduct regular epidemiological monitoring, which would study the population’s immunity against diphtheria and other controlled infections, and draw up a long-term strategic and tactical plan to address shortcomings in the work of mass immunoprophylaxis of the population.

Development and Evaluation of a Child Vaccination Chatbot Real-Time Consultation Messenger Service during the COVID-19 Pandemic

The decreased rate of children’s vaccination has resulted in outbreaks of vaccine-preventable diseases, and vaccination hesitancy is being brought about by the uncertainty caused by the continuing COVID-19 pandemic. With this study, we aimed to assess the efficacy of a child vaccination chatbot based on changes in variables such as vaccination information, motivation, self-efficacy, and vaccination behavioral intention. From 30 January to 15 February 2020, 65 parents raising children ≤35 months old who were expected to be vaccinated within three months participated in the trial through online recruitment. Participants were randomly assigned to either the experimental group (n = 34) or the control group (n = 31) and were followed up with over a period of 12 weeks. During this period, both groups of participants were provided with vaccination schedule reminders. The experimental group were additionally provided with vaccination-related information and motivation boosters by a chatbot (real-time consultation messenger service); the control group was provided the same information by brochure. Comparing both groups, the experimental group that used the chatbot scored higher on vaccination information, motivation, self-efficacy, and vaccination behavioral intention than the control group. This suggests that the chatbot provided useful and timely information to parents, increasing vaccination motivation, self-efficacy, and vaccination rates. This study provides evidence that chatbots are useful tools to encourage immunization through the provision of reminders and real-time consultation messenger services during the global health crisis and beyond.