Future Vaccine Policy Research Articles

The resurgence of pertussis in Central Serbia in the period from June to December 2023

Abstract Background There was a registered increase in the number of confirmed pertussis cases in Central Serbia between June and December 2023. Among the possible causes of pertussis resurgence are increased awareness of pertussis among healthcare workers, availability of the sensitive RT PCR method in diagnostic, the limited duration of vaccine-induced immunity as well as decline of immunization coverage influenced by the COVID-19 pandemic. Methods The nasopharyngeal samples from clinics and primary care departments were transferred to Institute of Public Health of Serbia. DNA was extracted from each sample using the MagMAX Viral/Pathogen kit. The presence of B. pertussis was determined using two PCR assays, VIASURE Bordetella Real Time PCR Detection Kit and Bosphore B. pertussis/parapertussis Genotyping Kit, Anatolia Geneworks. Results RT-PCR confirmed a total of 338 pertussis cases in Institute of Public Health of Serbia during the observed period. Most of confirmed cases were among children 9-14 years old (49,7%) followed by infants younger than 12 months (21,9%). The more severe cases were among the unvaccinated and uncomplete vaccinated infants, 78,4% of which required hospitalization with two deaths in this age group. Conclusions Based on the analysis of the obtained results, we can highlight the importance of using sensitive methods in pathogen detection. Rapid diagnosis, laboratory confirmation and notification ensure early public health intervention to minimize the spread of disease. Despite long tradition of mandatory immunization against pertussis in the Republic of Serbia, wanning of vaccine induced immunity poses potential risk for the resurgence of pertussis. For pertussis control, in the future, it will be essential to achieve high immunization coverage as well as to introduce a booster dose of pertussis containing vaccine for children aged 14 and to implement vaccination of pregnant women. Key messages • For the better pertussis control vaccination of adolescents and adults, as well as vaccination of pregnant women should be considered in the future vaccination policies. • Clinicians should consider pertussis in the differential diagnosis of persistent cough illness in people of all ages, even those previously immunized.

Estimating the impact of the COVID-19 vaccination programme in Ireland: December 2021-March 2023

Abstract Background In Autumn 2023, COVID-19 booster vaccines were offered to all those aged ≥50 years in Ireland. There was concern that vaccine fatigue would impact uptake. We aimed to quantify the direct impact of the COVID-19 vaccination programme on averted outcomes in individuals aged ≥50 years, during a period of Omicron variant dominance, to inform vaccination strategy and public health communication. Methods We conducted a retrospective observational study from December 2021 to March 2023 in Ireland. We considered as averted outcomes symptomatic SARS-CoV-2 presentations to primary care, emergency department (ED) presentations, hospitalisations, intensive care unit (ICU) admissions and deaths due to COVID-19. We used an adapted formula from other vaccine impact published studies, including national data on notified outcomes, vaccine coverage data and vaccine effectiveness (VE) estimates, sourced from the WHO’s live systematic VE review, to estimate the count and prevented fraction of outcomes in ≥ 50-year-olds averted by the COVID-19 vaccination programme. The number of expected outcomes in the absence of vaccination was calculated by summing the counts of outcomes observed and outcomes averted. Results Between December 2021 and March 2023, the COVID-19 vaccination programme averted 48,551 symptomatic presentations to primary care (36% of expected), 9,517 ED presentations (53% of expected), 102,160 hospitalisations (81% of expected), 3,303 ICU admissions (89% of expected) and 15,985 deaths (87% of expected). Conclusions During Omicron dominance, the COVID-19 vaccination programme averted symptomatic and severe outcomes, including deaths due to COVID-19, underscoring the benefits of COVID-19 vaccination. In the context of vaccine fatigue emerging as an important public health issue in Ireland and internationally, these findings can inform future COVID-19 booster vaccination programmes and communication about the reason for and importance of COVID-19 vaccination. Key messages • The COVID-19 vaccination programme in Ireland prevented illness and death in people aged ≥50-years. Vaccination therefore protected population health and the healthcare system. • These findings can be used to inform future COVID-19 vaccination policies, planning for winter, pandemic preparedness and communisation about the importance of ongoing COVID-19 vaccination programmes.

Lessons for Future Vaccination Policies: COVID-19 Vaccination Intention in People With and Without Chronic Diseases

PurposeThis study compared COVID-19 vaccination intentions in those with and without chronic diseases (CDs and non-CDs) in South Korea. We hypothesized that the factors associated with COVID-19 vaccination intentions would differ between CDs and non-CDs in South Korea. MethodUsing survey data collected through a Korean online panel in June 2021, we conducted a cross-sectional secondary data analysis. Of the 2,292 participants, 411 had at least one chronic disease. To construct a comparable dataset, we selected non-CDs via a 1:1 case-control matching for age and gender. We then utilized a multivariable binary logistic regression model to explore the factors contributing to COVID-19 vaccination intentions in CDs and non-CDs. ResultsAll told, 75% of participants in both groups indicated that they intended to vaccinate against COVID-19. In both groups, those who mistrusted general vaccine benefits reported significantly lower COVID-19 vaccination intentions. Regarding factors associated with vaccination intentions, CDs identified anxiety regarding coronavirus and exposure to COVID-19 vaccination promotions at the community level, while non-CDs highlighted hesitancy regarding vaccines and confidence in government/health services. ConclusionImproving vaccination acceptance will require the development and implementation of tailored approaches for CDs and non-CDs and efforts to minimize general vaccine mistrust.

The colonial effect: Language, trust and attitudes to science as predictors of vaccine hesitancy across Africa

Perceptions of vaccine safety, importance and effectiveness are at the core of vaccine hesitancy around the world, and Africa has had its own share of vaccine revolts. This study uses the 2018 Wellcome Global Monitor on public perceptions of vaccines in 40 African countries to examine the predictors of vaccine hesitancy. It examines levels of hesitancy from a language perspective, comparing French speakers with others, mostly English speakers. Results show that French speakers were significantly more hesitant about importance and safety, while English speakers and others were more hesitant about effectiveness. This reflects the continuing influence of colonial ties on African countries. Respondents with high levels of trust in social actors (such as national government, journalists, people neighborhood, doctors and nurses) were also more hesitant about the safety and effectiveness of vaccines, indicating the importance of non-scientists in influencing vaccine hesitancy. Those with high levels of education were more likely to be hesitant about vaccines in general, indicating that having more education may have an opposite effect. Perception of science as progress was significant for all three hesitancy types, indicating that Africans with more progressive attitudes were less likely to worry about the importance, safety and effectiveness of vaccines. At the country level, there was no overarching predictor, indicating the strong role of local social and cultural factors. These findings improve our understanding of the drivers of vaccine hesitancy in Africa and provide valuable input for future vaccine policy and health-awareness campaigns.

Original COVID-19 priming regimen impacts the immunogenicity of bivalent BA.1 and BA.5 boosters.

Waning antibody responses after COVID-19 vaccination combined with the emergence of the SARS-CoV-2 Omicron lineage led to reduced vaccine effectiveness. As a countermeasure, bivalent mRNA-based booster vaccines encoding the ancestral spike protein in combination with that of Omicron BA.1 or BA.5 were introduced. Since then, different BA.2-descendent lineages have become dominant, such as XBB.1.5, JN.1, or EG.5.1. Here, we report post-hoc analyses of data from the SWITCH-ON study, assessing how different COVID-19 priming regimens affect the immunogenicity of bivalent booster vaccinations and breakthrough infections (NCT05471440). BA.1 and BA.5 bivalent vaccines boosted neutralizing antibodies and T-cells up to 3 months after boost; however, cross-neutralization of XBB.1.5 was poor. Interestingly, different combinations of prime-boost regimens induced divergent responses: participants primed with Ad26.COV2.S developed lower binding antibody levels after bivalent boost while neutralization and T-cell responses were similar to mRNA-based primed participants. In contrast, the breadth of neutralization was higher in mRNA-primed and bivalent BA.5 boosted participants. Combined, our data further support the current use of monovalent vaccines based on circulating strains when vaccinating risk groups, as recently recommended by the WHO. We emphasize the importance of the continuous assessment of immune responses targeting circulating variants to guide future COVID-19 vaccination policies.

Impact on the time elapsed since SARS-CoV-2 infection, vaccination history, and number of doses, on protection against reinfection

SARS-CoV-2 reinfections have been frequent, even among those vaccinated. The aim of this study is to know if hybrid immunity (infection + vaccination) is affected by the moment of vaccination and number of doses received. We conducted a retrospective study in 746 patients with a history of COVID-19 reinfection and recovered the dates of infection and reinfection and vaccination status (date and number of doses). To assess differences in the time to reinfection(tRI) between unvaccinated, vaccinated before 6 months, and later; and comparing one, two or three doses (incomplete, complete and booster regime) we performed the log-rank test of the cumulative incidence calculated as 1 minus the Kaplan–Meier estimator. Also, an adjusted Cox-regression was performed to evaluate the risk of reinfection in all groups. The tRI was significantly higher in those vaccinated vs. non-vaccinated (p < 0.001). However, an early incomplete regime protects similar time than not receiving a vaccine. Vaccination before 6 months after infection showed a lower tRI compared to those vaccinated later with the same regime (adj-p < 0.001). Actually, early vaccination with complete and booster regimes provided lower length of protection compared to vaccinating later with incomplete and complete regime, respectively. Vaccination with complete and booster regimes significantly increases the tRI (adj-p < 0.001). Vaccination increases the time it takes for a person to become reinfected with SARS-CoV-2. Increasing the time from infection to vaccination increases the time in which a person could be reinfected and reduces the risk of reinfection, especially in complete and booster regimes. Those results emphasize the role of vaccines and boosters during the pandemic and can guide strategies on future vaccination policy.

EXAMINING COVID-19 VACCINE–RELATED AGEISM IN TWITTER DATA

Abstract During the pandemic, many high-income countries prioritized older adults for COVID-19 vaccination in an attempt to reduce mortality. This prioritization may have exacerbated ageism and intergenerational conflict, especially with the limited quantity of COVID-19 vaccines. This presentation examines vaccine-related ageism during COVID-19 on social media to inform future vaccination campaigns and policies. Using Twitter, we gathered 1,369 relevant tweets using the Twint application in Python from December 8, 2020 to December 31, 2021. Tweets were assessed using inductive thematic analysis and steps were taken to ensure rigor and trustworthiness. Based on our analysis, four main themes were identified including: i) Blame and aggression; ii) Misinformation and mocking content; iii) Ageist political insults; and iv) Challenging ageism. Our study identified issues of false information, hate speech, and ageist political insults that are contributing to intergenerational conflict. Although some tweets challenged this derogatory messaging and demonstrated intergenerational unity, our findings suggest ageism contributed to COVID-19 vaccine hesitancy among older adults. Accordingly, urgent action is required to challenge vaccine misinformation, counter aggressive ageist content, and support intergenerational unity during the pandemic.

Real-world effectiveness of full and booster mRNA vaccination for coronavirus disease 2019 against disease severity during the delta- and omicron-dominant phases: A propensity score-matched cohort study using the nationwide registry data in Japan

BackgroundTo date, few studies from the Asian region have reported the effectiveness of messenger ribonucleic acid coronavirus disease 2019 (COVID-19) vaccines against disease progression and death after hospitalization. MethodsWe evaluated the data from the COVID-19 registry in Japan during the delta- and omicron-dominant phases. A propensity score-matched cohort study was conducted between the incompletely (0–1 dose) and fully (2 doses) vaccinated groups during the delta-dominant phase and among the incompletely, fully, and booster (3 doses) vaccinated groups during the omicron-dominant phase. ResultsIn the delta-dominant phase, 411 pairs were matched. The fully vaccinated group showed a significantly lower oxygen supplementation rate (24.1 % vs. 41.1 %, p < 0.001) but little difference in the mortality rate (2.2 % vs. 2.9 %, p = 0.66). In the omicron-dominant phase, 1494 pairs from the incompletely and fully vaccinated groups, and 425 pairs from the fully and booster vaccinated groups were matched. Full vaccination reduced both the oxygen supplementation rate (18.6 % vs 25.7 %, p < 0.001) and mortality rate (0.7 % vs 2.3 %, p < 0.001). Booster vaccination showed little difference in either the rate of oxygen supplementation (21.2 % vs. 24.7 %, p = 0.25) or mortality (1.2 % vs. 2.6 %, p = 0.21) compared with full vaccination. ConclusionsFull vaccination reduced disease severity during the delta- and omicron-dominant phases; booster vaccination did not further enhance the protective effects against disease progression during the omicron-dominant phase compared to full vaccination. Future vaccine strategies and policy decisions should consider preventing infection or disease progression in the target population, as well as the characteristics of the dominant variant in that phase.

Epidemiology and clinical characteristics of severe acute respiratory infections among hospitalized children under 5 years of age in a tertiary care center in Bangkok, Thailand, 2019–2020

BackgroundAcute respiratory infections (ARIs) are common in children and can range in severity from mild self-limiting illnesses to more severe conditions such as pneumonia and respiratory failure. Data on the epidemiology of viral and bacterial pathogens causing ARIs in children are scarce in this region. This study aimed to investigate the epidemiology and clinical manifestations of pathogens in children aged ≤5 years presenting with severe acute respiratory infection (SARI) in Bangkok, Thailand. The impact of rapid multiplex PCR-based testing on clinical management is also explored. MethodsThis cross-sectional study enrolled consecutive children aged ≤5 years presenting with SARI at a tertiary care centre in Bangkok, Thailand, between 2019 and 2020. Nasopharyngeal swabs were collected once at admission, and viral and bacterial pathogens were tested using the QIAstat-Dx respiratory panel. ResultsA total of 169 children were enrolled in this study. At least one pathogenic virus was detected in 91.7 % of participants. Based on the final diagnoses made upon discharge, 30.2 % had upper respiratory tract infection, whereas 66.3 % had lower respiratory tract infection. Pneumonia was the most common diagnosis (59.2 %). The most common pathogen identified was rhino/enterovirus (45.2 %), followed by respiratory syncytial virus (31.6 %) and parainfluenza virus (14.2 %). Co-infection was found in 15.4 % and was not associated with increased disease severity. ConclusionsThis study provides additional insights into the pathogen profiles, clinical diagnosis, and co-infection combinations of ARIs in hospitalized children. This information is useful for diagnosis and treatment of ARIs, as well as implementation of appropriate infection control measures and guidance for future vaccine policy development.

Potential Determinants Contributing to COVID-19 Vaccine Acceptance and Hesitancy in Taiwan: Rapid Qualitative Mixed Methods Study.

Although vaccination has been shown to be one of the most important interventions, COVID-19 vaccine hesitancy remains one of the top 10 global public health challenges worldwide. The objective of this study is to investigate (1) major determinants of vaccine hesitancy, (2) changes in the determinants of vaccine hesitancy at different time periods, and (3) the potential factors affecting vaccine acceptance. This study applied a mixed methods approach to explore the potential determinants contributing to vaccine hesitancy among the Taiwanese population. The quantitative design of this study involved using Google Trends search query data. We chose the search term "" (vaccine), selected "" (Taiwan) as the location, and selected the period between December 18, 2020, and July 31, 2021. The rising keywords related to vaccine acceptance and hesitancy were collected. Based on the responses obtained from the qualitative study and the rising keywords obtained in Google Trends, the 3 most popular keywords related to vaccine hesitancy were identified and used as search queries in Google Trends between December 18, 2020, and July 31, 2021, to generate relative search volumes (RSVs). Lastly, autoregressive integrated moving average modeling was used to forecast the RSVs for the 3 keywords between May 29 and July 31, 2021. The estimated RSVs were compared to the observed RSVs in Google Trends within the same time frame. The 4 prevailing factors responsible for COVID-19 vaccine acceptance and hesitancy were doubts about the government and manufacturers, side effects, deaths associated with vaccination, and efficacy of vaccination. During the vaccine observation period, "political role" was the overarching consideration leading to vaccine hesitancy. During the peak of the pandemic, side effects, death, and vaccine protection were the main factors contributing to vaccine hesitancy. The popularity of the 3 frequently searched keywords "side effects," "vaccine associated deaths," and "vaccine protection" continued to rise throughout the pandemic outbreak. Lastly, the highest Google search queries related to COVID-19 vaccines emerged as "side effects" prior to vaccination, deaths associated with vaccines during the period when single vaccines were available, and "side effects" and "vaccine protection" during the period when multiple vaccines were available. Investigating the key factors influencing COVID-19 vaccine hesitancy appears to be a fundamental task that needs to be undertaken to ensure effective implementation of COVID-19 vaccination. Google Trends may be used as a complementary infoveillance tool by government agencies for future vaccine policy implementation and communication.

Viral genetic clustering and transmission dynamics of the 2022 mpox outbreak in Portugal

Pathogen genome sequencing during epidemics enhances our ability to identify and understand suspected clusters and investigate their relationships. Here, we combine genomic and epidemiological data of the 2022 mpox outbreak to better understand early viral spread, diversification and transmission dynamics. By sequencing 52% of the confirmed cases in Portugal, we identified the mpox virus sublineages with the highest impact on case numbers and fitted them into a global context, finding evidence that several international sublineages probably emerged or spread early in Portugal. We estimated a 62% infection reporting rate and that 1.3% of the population of men who have sex with men in Portugal were infected. We infer the critical role played by sexual networks and superspreader gatherings, such as sauna attendance, in the dissemination of mpox virus. Overall, our findings highlight genomic epidemiology as a tool for the real-time monitoring and control of mpox epidemics, and can guide future vaccine policy in a highly susceptible population.

Mpox Outbreak 2022: A Comparative Analysis of the Characteristics of Individuals Receiving MVA-BN Vaccination and People Diagnosed with Mpox Infection in Milan, Italy.

Mpox caused a worldwide outbreak in 2022, disproportionately affecting MSM reporting high-risk sexual behaviors. The aim of this study was to compare the characteristics of people receiving MVA-BN vaccination with those of individuals diagnosed with mpox to guide future vaccination policies. This was a retrospective study on people with mpox infection or vaccination at San Raffaele Scientific Institute, Milan, Italy, from May to November 2022. Characteristics were compared using Mann-Whitney or chi-square/Fisher's exact tests; multivariable logistic regression and classification tree analysis were applied. Overall, 473 vaccinated individuals and 135 with mpox were included; 472/473 and 134/135 were MSM. People with mpox were more frequently living with HIV (48.9% vs. 22.4%, p < 0.001), had ≥1 previous STI (75.6% vs. 35.7%, p < 0.001), were chemsex users (37.8% vs. 6.34%, p < 0.001), were with a higher number of partners (23.0% vs. 1.69%, p < 0.001), and had engaged in group sex (55.6% vs. 24.1%, p < 0.001). At multivariable analysis, PLWH (aOR = 2.86, 95%CI = 1.59-5.19, p < 0.001), chemsex users (aOR = 2.96, 95%CI = 1.52-5.79, p = 0.001), those with previous syphilis (aOR = 4.11, 95%CI = 2.22-7.72, p < 0.001), and those with >10 partners (aOR = 11.56, 95%CI = 6.60-21.09, p < 0.001) had a higher risk of infection. This study underscores the importance of prioritizing MSM with prior STIs and multiple partners as well as chemsex users in vaccination policies to curb mpox spread. A destigmatized assessment of sexual history is vital for comprehensive sexual health strategies.

Using Twitter to Understand COVID-19 Vaccine-Related Ageism During the Pandemic.

During the rollout of coronavirus 2019 (COVID-19) vaccines, older adults in high-income countries were often prioritized for inoculation in efforts to reduce COVID-19-related mortality. However, this prioritization may have contributed to intergenerational tensions and ageism, particularly with the limited supply of COVID-19 vaccines. This study examines Twitter discourse to understand vaccine-related ageism during the COVID-19 pandemic to inform future vaccination policies and practices to reduce ageism. We collected 1,369 relevant tweets on Twitter using the Twint application in Python from December 8, 2020, to December 31, 2021. Tweets were analyzed using thematic analysis, and steps were taken to ensure rigor. Our research identified four main themes including (a) blame and hostility: "It's all their fault"; (b) incompetence and misinformation: "clueless boomer"; (c) ageist political slander; and (d) combatting ageism: advocacy and accessibility. Our findings exposed issues of victim-blaming, hate speech, pejorative content, and ageist political slander that is deepening the divide of intergenerational conflict. Although a subset of tweets countered negative outcomes and demonstrated intergenerational solidarity, our findings suggest that ageism may have contributed to COVID-19 vaccine hesitancy among older adults. Consequently, urgent action is needed to counter vaccine misinformation, prohibit aggressive messaging, and promote intergenerational unity during the COVID-19 pandemic and beyond.

PCR98 A Literature Review Assessing the Most Common Attributes Used in Stated-Preference Studies Assessing Influenza Vaccination: Do We Know What Health Care Professionals Value?

Several attributes may be important in flu vaccine and since Covid-19, the role of health care professionals (HCPs) may have become more important in increasing flu vaccine uptake. We conducted a literature review to assess if previous preference research could inform future flu vaccination policies. We conducted a literature review to assess the most common attributes used in stated-preference studies to determine seasonal flu vaccination preferences. PubMed with key terms such as “discrete choice“, “stated preference“ and “flu/vaccin*” was used to retrieve relevant research. In total, twelve studies investigating consumer and HCP preferences for flu vaccines using a discrete-choice experiment were included. Six studies were conducted in vaccine-eligible populations, three were conducted with parents (specifically, two focused on older adults and one elicited preferences directly from HCPs in Hong Kong). Three studies were conducted in the Netherlands, two in Japan and four in China. Vaccine efficacy was most often framed in terms of percentage (n=7). Out of pocket cost and duration of immunity were common attributes. Source of recommendation for vaccination (i.e., regulatory or public health body) was assessed in 25% of the studies. In studies assessing parental preferences for their children influenza vaccination, risks of fewer side effects were, unsurprisingly, preferred. Finally, among HCPs, vaccine effectiveness and vaccination location (staff clinic/mobile vaccination center) were most important and could increase the probability of vaccination. Information incompleteness and asymmetry could play a role in vaccine hesitation and/or aversion. To increase vaccination rates, evidence on the attributes perceived to be important to both HCPs and the general population may help the design and delivery of vaccines that match consumers’ preferences. Currently, there is a critical need for more stated-preference studies among HCPs to better understand the attributes likely to increase vaccination rates against seasonal influenza.

백신 부작용과 국가책임

Vaccines remain an unstable and controversial technology in South Korean society, as evidenced by the adverse event debate during the COVID-19 vaccine rollout. The Korean government's primary policy response to this has been to implement a comprehensive immunization compensation system that provides state-level compensation to those who experience harm, even if a direct causal link to vaccination cannot be proven. Although South Korea's immunization compensation system was enacted in 1994 and fully implemented in 1995, government, medical, and public debates surrounding it have been ongoing since the mass vaccination campaigns of Korea. This study examines how attempts to manage vaccine adverse events in Korea have been shaped by conflicts between government, medical professionals, and the public over vaccination, particularly over adverse events. At the same time, the technical limitations of each vaccine led to questions of safety, and these limitations shaped the public's perceptions of effectiveness and trust in individual vaccines. This study focuses on three of the most widely recognized vaccine-related adverse reactions: the typhoid vaccine of the 1960s, the DPT vaccine of the 1970s, and the Japanese encephalitis vaccine of the 1990s. These cases reveal that state-oriented disease control initiatives were not always successful in mobilizing the public and medical personnel unilaterally, but rather that there were various resistances and backlash, requiring detailed policies such as “no-fault” compensation systems to manage them. Furthermore, these cases suggest that for future systematic vaccine policy formulation, it is necessary to build a historical understanding of the technical limitations of individual vaccines and the experiences and responses to their adverse effects, rather than analyzing vaccine policy as a single entity.

Waning anti-SARS-CoV-2 receptor-binding domain total antibody in CoronaVac-vaccinated individuals in Indonesia.

Background: The decrease of immunity acquired from COVID-19 vaccines is a potential cause of breakthrough infection. Understanding the dynamics of immune responses of vaccine-induced antibodies post-vaccination is important. This study aimed to measure the level of anti-SARS-CoV-2 receptor-binding domain (RBD) total antibody in individuals at different time points upon the receipt of the second dose of CoronaVac vaccine, as well as evaluate the plausible associated factors. Methods: A cross-sectional study was conducted among CoronaVac-vaccinated residents in Banda Aceh, Indonesia. The level of anti-SARS-CoV-2 RBD total antibody was measured using Elecsys immunoassay. A set of standardized and validated questionnaires were used to assess the demographics and other associated factors. Results: Our results showed waning anti-SARS-CoV-2 RBD total antibody titres over time post-vaccination. Compared to samples of the first month post-vaccination, the antibody titres were significantly lower than those of five-months (mean 184.6 vs. 101.8 U/mL, p = 0.009) and six-months post-vaccination (mean 184.6 vs. 95.59 U/mL, p = 0.001). This suggests that the length of time post-vaccination was negatively correlated with titre of antibody. A protective level of antibody titres (threshold of 15 U/mL) was observed from all the samples vaccinated within one to three months; however, only 73.7% and 78.9% of the sera from five- and six-months possessed the protective titres, respectively. The titre of antibody was found significantly higher in sera of individuals having a regular healthy meal intake compared to those who did not (mean 136.7 vs. 110.4 U/mL, p = 0.044), including in subgroup analysis that included those five to six months post-vaccination only (mean 79.0 vs. 134.5 U/mL, p = 0.009). Conclusions: This study provides insights on the efficacy of CoronaVac vaccine in protecting individuals against SARS-CoV-2 infection over time, which may contribute to future vaccination policy management to improve and prolong protective strategy.

National surveillance data analysis of COVID-19 vaccine uptake in England by women of reproductive age

Women of reproductive age are a group of particular concern with regards to vaccine uptake, related to their unique considerations of menstruation, fertility, and pregnancy. To obtain vaccine uptake data specific to this group, we obtained vaccine surveillance data from the Office for National Statistics, linked with COVID-19 vaccination status from the National Immunisation Management Service, England, from 8 Dec 2020 to 15 Feb 2021; data from 13,128,525 such women at population-level, were clustered by age (18–29, 30–39, and 40–49 years), self-defined ethnicity (19 UK government categories), and index of multiple deprivation (IMD, geographically-defined IMD quintiles). Here we show that among women of reproductive age, older age, White ethnicity and being in the least-deprived index of multiple deprivation are each independently associated with higher vaccine uptake, for first and second doses; however, ethnicity exerts the strongest influence (and IMD the weakest). These findings should inform future vaccination public messaging and policy.

Developing an evidence-based TISM: an application for the success of COVID-19 Vaccination Drive.

The study illustrates an application of evidence data for performing Total Interpretive Structural Modeling (TISM). TISM is widely used to analyze the critical success factors or inhibitors and their interlinkages. This study uses learning from evidence data, specifically social media analytics, to identify the relationship between the elements. Thus, it leads to the advancement of the TISM-P methodology with evidence-based TISM (TISM-E). This study uses Twitter as a source of evidence data. Further, 2,60,297 tweets were used to illustrate the process of TISM-E. The paper demonstrates the application of TISM-E for the success of the COVID-19 vaccination drive. The pandemic effects are long-term; therefore, the hierarchical model developed shows a sustainable approach for vaccinating maximum population. Further, the framework developed will ensure the distribution efficacy of vaccines. In addition, it will aid practitioners in developing future vaccination policies. The enhanced model provides evidence for polarity (positive/negative) of relationships and can help to build propositions for theory development. The study contributes to healthcare, modeling research, and graph-theoretic literature.

Individual Preferences for COVID-19 Vaccination under the China's 2021 National Vaccination Policy: A Discrete Choice Experiment Study.

(1) Background: Since China’s national vaccination policy announcement in January 2021, individual vaccination preferences related to vaccine characteristics, social relationships, sociodemographic characteristics and cognition remain opaque. This study aims to investigate vaccination preferences regarding these attributes, and to assess changes in individual vaccine preferences since the pre-2021 emergency vaccination phase. (2) Methods: The two-part questionnaire surveyed 849 individuals between May and June 2021 in Qingdao, China. The survey contained eight binary choice tasks that investigated preference trade-offs. Respondents’ sociodemographic characteristics, including age, sex, urban/rural residence, income, education and whether living with the young or old, were also collected. Conditional logit, mixed logit and latent class models were used to quantify preference utility and identify preference heterogeneity. (3) Results: Vaccine effectiveness, vaccine side effects, duration of protection and probability of infection all significantly affected vaccination utility. Preference heterogeneity based on individual social relationships and sociodemographic characteristics were also established. Marginal analysis showed that compared to the pre-2021 phase, individuals’ preferences had shifted towards vaccines with longer protection periods and better accessibility. (4) Conclusion: This study will inform the full rollout of China’s 2021 national vaccination program and provide valuable information for future vaccination policy design to meet resurgent COVID-19 risks.

Waning anti-SARS-CoV-2 neutralizing antibody in CoronaVac-vaccinated individuals in Indonesia

Background: The decrease of immunity acquired from COVID-19 vaccines is a potential cause of breakthrough infection. Understanding the dynamics of immune responses of vaccine-induced antibodies post-vaccination is important. This study aimed to measure the level of neutralizing antibody (NAb) anti-SRBD in individuals at different time points upon the receipt of the second dose of CoronaVac vaccine, as well as evaluate the plausible associated factors. Methods: A cross-sectional study was conducted among CoronaVac-vaccinated residents in Banda Aceh, Indonesia. The level of NAb titre was measured using Elecsys Anti-SARS-CoV-2 S immunoassay. A set of standardized and validated questionnaires were used to assess the demographics and other plausible associated factors. Results: Our results showed waning SARS-Cov-2 NAb titres over time post-vaccination. Compared to samples of the first month post-vaccination, the levels of NAb titres were significantly lower than those of five-months (mean 184.6 vs. 101.8 IU/mL, p = 0.009) and six-months post-vaccination (mean 184.6 vs. 95.59 IU/mL, p = 0.001). This suggests that the length of time post-vaccination was negatively correlated with antibody anti-SRBD titre. A protective level of NAbs titres (threshold of 15 IU/mL) was observed from all the samples vaccinated within one to three months; however, only 73.7% and 78.9% of the sera from five- and six-months possessed the protective titres against SARS-CoV-2, respectively. The titre of NAb anti-SRBD was found significantly higher in sera of individuals having a regular healthy meal intake compared to those who did not (mean 136.7 vs. 110.4 IU/mL, p = 0.044), including in subgroup analysis that included those five to six months post-vaccination only (mean 79.0 vs. 134.5 IU/mL, p = 0.009). Conclusions: This study provides insights on the efficacy of CoronaVac vaccine in protecting individuals against SARS-CoV-2 infection over time, which may contribute to future vaccination policy management to improve and prolong protective strategy.