COVID-19 IgG seropositivity and its determinants in occupational groups of varying infection risks in two Andean cities of Ecuador before mass vaccination.

BACKGROUND: The COVID-19 pandemic has caused over 68.7 million infections and 1.35 million deaths in South America. There are limited data on SARS-CoV-2 seropositivity and its determinants from Andean countries prior to mass vaccinations against COVID-19. OBJECTIVE: To estimate SARS-CoV-2 seropositivity and its determinants before vaccination in occupational groups of adults presumed to have different levels of exposure and associations with potential symptomatology. METHODS: We measured seropositivity of anti-SARS-CoV-2 IgG antibodies in a cross-sectional study of vaccine-naïve adults aged 18 years and older, recruited within three occupational risk groups (defined as low [LR], moderate [MR], and high [HR]) between January and September 2021 in two Andean cities in Ecuador. Associations with risk factors were estimated using logistic regression. RESULTS: In a sample of 882 adults, IgG seropositivity for the three different occupational risk groups was 39.9% (CI 95% 35.3-44.6), 74.6% (CI 95% 66.4-81.4), and 39.0% (CI 95% 34.0-44.4) for the HR, MR, and LR groups, respectively. History of an illness with loss of taste and/or smell was significantly associated with seropositivity in all occupational groups, with adjusted ORs of 14.31 (95%CI, 5.83-35.12; p<0.001), 14.34 (95%CI 3.01-68.42; p<0.001), and 8.79 (95%CI 2.69-28.72; p<0.001), for the HR, MR, and LR groups, respectively; while fever was significant for the LR group with an adjusted OR of 1.24 (95%CI, 1.11-4.57; p = 0.025) and myalgia for the HR group with an adjusted OR of 2.07 (95%CI, 1.13-3.81; p = 0.019). CONCLUSION: Notable proportions of seropositivity were seen in all occupational groups between January and September 2021 prior to mass vaccination. Loss of taste and/or smell was strongly associated with presence of anti-SARS-CoV-2 IgG antibodies irrespective of presumed occupational exposure risk.

Modeling hepatitis A epidemiological profiles and estimating the pediatric vaccination threshold in the Russian Federation.

Background: To combat the hesitancy towards implementing a hepatitis A universal mass vaccination (UMV) strategy and to provide healthcare authorities with a comprehensive analysis of the potential outcomes and benefits of the implementation of such a vaccination program, we projected HAV seroprevalence and incidence rates in the total population of the Russian Federation and estimated the pediatric vaccination threshold required to achieve an incidence level of less than 1 case per 100,000 using a new mathematical model. Methods: A dynamic age-structured SEIRV (susceptible-exposed-infectious-recovered-vaccinated) compartmental model was developed and calibrated using demographic, seroprevalence, vaccination, and epidemiological data from different regions of the Russian Federation. This model was used to project various epidemiological measures. Results: The projected national average age at the midpoint of population immunity increases from 40 years old in 2020 to 50 years old in 2036 and is shifted even further to the age of 70 years in some regions of the country. An increase of varying magnitude in the incidence of symptomatic HAV infections is predicted for all study regions and for the Russian Federation as a whole between 2028 and 2032, if the HAV vaccination coverage level remains at the level of 2022. The national average vaccination coverage level required to achieve a symptomatic HAV incidence rate below 1 case per 100,000 by 2032 was calculated to be 69.8% if children aged 1-6 years are vaccinated following the implementation of a UMV program or 34.8% if immunization is expanded to children aged 1-17 years. Conclusion: The developed model provides insights into a further decline of herd immunity to HAV against the background of ongoing viral transmission. The current favorable situation regarding hepatitis A morbidity is projected to be replaced by an increase in incidence rates if vaccination coverage remains at the current levels. The obtained results support the introduction of a hepatitis A UMV strategy in the Russian Federation.

Comprehensive Review on the Use of Oral Cholera Vaccine (OCV) in Ethiopia: 2019 to 2023.

BACKGROUND: Cholera outbreaks in Ethiopia necessitate frequent mass oral cholera vaccine (OCV) campaigns. Despite this, there is a notable absence of a comprehensive summary of these campaigns. Understanding national OCV vaccination history is essential to design appropriate and effective cholera control strategies. Here, we aimed to retrospectively review all OCV vaccination campaigns conducted across Ethiopia between 2019 and 2023. METHODS: The OCV request records from 2019 to October 2023 and vaccination campaign reports for the period from 2019 to December 2023 were retrospectively accessed from the Ethiopia Public Health Institute (EPHI) database. Descriptive analysis was conducted using the retrospective data collected. RESULTS: From 2019 to October 2023, Ethiopian government requested 32 044 576 OCV doses (31 899 576 doses to global stockpile; 145 000 doses to outside of stockpile). Around 66.3% of requested doses were approved; of which 90.4% were received. Fifteen OCV campaigns (12 reactive and 3 pre-emptive) were conducted, including five two-dose campaigns with varying dose intervals and single-dose campaigns partially in 2019 and entirely in 2021, 2022 and 2023. Overall vaccine administrative coverage was high; except for Tigray region (41.8% in the 1st round; 2nd round didn't occur). The vaccine administrative coverage records were documented, but no OCV coverage survey data was available. CONCLUSIONS: This study represents the first comprehensive review of OCV campaigns in Ethiopia spanning the last five years. Its findings offer valuable insights into informing future cholera control strategies, underscoring the importance of monitoring and evaluation despite resource constraints. Addressing the limitations in coverage survey data availability is crucial for enhancing the efficacy of future campaigns.

Optimizing the location of vaccination sites to stop a zoonotic epidemic.

Mass vaccinations are crucial public health interventions for curbing infectious diseases. Canine rabies control relies on mass dog vaccination campaigns (MDVCs) that are held annually across the globe. Dog owners must bring their pets to fixed vaccination sites, but sometimes target coverage is not achieved due to low participation. Travel distance to vaccination sites is an important barrier to participation. We aimed to increase MDVC participation in silico by optimally placing fixed-point vaccination locations. We quantified participation probability based on walking distance to the nearest vaccination site using regression models fit to participation data collected over 4 years. We used computational recursive interchange techniques to optimally place fixed-point vaccination sites and compared predicted participation with these optimally placed vaccination sites to actual locations used in previous campaigns. Algorithms that minimized average walking distance or maximized expected participation provided the best solutions. Optimal vaccination placement is expected to increase participation by 7% and improve spatial evenness of coverage, resulting in fewer under-vaccinated pockets. However, unevenness in workload across sites remained. Our data-driven algorithm optimally places limited resources to increase overall vaccination participation and equity. Field evaluations are essential to assess effectiveness and evaluate potentially longer waiting queues resulting from increased participation.

Assessing seropositivity of MMR antibodies in individuals aged 2-22: evaluating routine vaccination effectiveness after the 2003 mass campaign-a study from Iran's National Measles Laboratory.

BACKGROUND AND PURPOSE: The seroprevalence of antibodies against measles, mumps, and rubella (MMR) was evaluated 17 years following a mass vaccination campaign in individuals aged 2 to 22 years who had received routine immunization but were not eligible for an extended immunization program. METHODS: Samples were acquired from Iran's National Measles Laboratory (NML), with individuals showing positive IgM results excluded. Out of the samples collected in 2020, a random selection of 290 serum samples was chosen, representing individuals between the ages of 2 and 22 years from diverse regions in the country. These samples were subjected to analysis using an enzyme-linked immunosorbent assay (ELISA) to quantify specific IgG antibodies against MMR. RESULTS: The seroprevalence rates of antibodies for measles, mumps, and rubella were determined to be 76.2%, 89.3%, and 76.9%, respectively. Younger age groups exhibited higher seropositivity rates for measles and mumps, whereas the 7- to 11-year-old group demonstrated the highest seropositivity rate for rubella. A reduction in antibody status was observed from younger to older age groups, particularly those aged 17-22. CONCLUSION: The study unveiled suboptimal antibody levels for measles and rubella, highlighting the necessity for further investigation and potential adjustments to future vaccination strategies. Moreover, the decline in antibody status post-vaccination can accumulate in seronegative individuals over time, elevating the risk of outbreaks.

Vaccine effectiveness in reducing COVID-19-related hospitalization after a risk-age-based mass vaccination program in a Chilean municipality: A comparison of observational study designs.

BACKGROUND: Case-control studies involving test-negative (TN) and syndrome-negative (SN) controls are reliable for evaluating influenza and rotavirus vaccine effectiveness (VE) during a random vaccination process. However, there is no empirical evidence regarding the impact in real-world mass vaccination campaigns against SARS-CoV-2 using TN and SN controls. OBJECTIVE: To compare in the same population the effectiveness of SARS-CoV-2 vaccination on COVID-19-related hospitalization rates across a cohort design, TN and SN designs. METHOD: We conducted an unmatched population-based cohort, TN and SN case-control designs linking data from four data sources (public primary healthcare system, hospitalization registers, epidemiological surveillance systems and the national immunization program) in a Chilean municipality (Rancagua) between March 1, 2021 and August 31, 2021. The outcome was COVID-19-related hospitalization. To ensure sufficient sample size in the unexposed group, completion of follow-up in the cohort design, and sufficient time between vaccination and hospitalization in the case-control design, VE was estimated comparing 8-week periods for each individual. RESULTS: Among the 191,505 individuals registered in the primary healthcare system of Rancagua in Chile on March 1, 2021; 116,453 met the cohort study's inclusion criteria. Of the 9,471 hospitalizations registered during the study period in the same place, 526 were COVID-19 cases, 108 were TN controls, and 1,628 were SN controls. For any vaccine product, the age- and sex-adjusted vaccine effectiveness comparing fully and nonvaccinated individuals was 67.2 (55.7-76.3) in the cohort design, whereas it was 67.8 (44.1-81.4) and 77.9 (70.2-83.8) in the TN and SN control designs, respectively. CONCLUSION: The VE of a COVID-19 vaccination program based on age and risk groups tended to differ across the three observational study designs. The SN case-control design may be an efficient option for evaluating COVID-19 VE in real-world settings.

Measles Outbreak Associated with a Migrant Shelter - Chicago, Illinois, February-May 2024.

Measles, a highly contagious respiratory virus with the potential to cause severe complications, hospitalization, and death, was declared eliminated from the United States in 2000; however, with ongoing global transmission, infections in the United States still occur. On March 7, 2024, the Chicago Department of Public Health (CDPH) confirmed a case of measles in a male aged 1 year residing in a temporary shelter for migrants in Chicago. Given the congregate nature of the setting, high transmissibility of measles, and low measles vaccination coverage among shelter residents, measles virus had the potential to spread rapidly among approximately 2,100 presumed exposed shelter residents. CDPH immediately instituted outbreak investigation and response activities in collaboration with state and local health departments, health care facilities, city agencies, and shelters. On March 8, CDPH implemented active case-finding and coordinated a mass vaccination campaign at the affected shelter (shelter A), including vaccinating 882 residents and verifying previous vaccination for 784 residents over 3 days. These activities resulted in 93% measles vaccination coverage (defined as receipt of ≥1 recorded measles vaccine dose) by March 11. By May 13, a total of 57 confirmed measles cases associated with residing in or having contact with persons from shelter A had been reported. Most cases (41; 72%) were among persons who did not have documentation of measles vaccination and were considered unvaccinated. In addition, 16 cases of measles occurred among persons who had received ≥1 measles vaccine dose ≥21 days before first known exposure. This outbreak underscores the need to ensure high vaccination coverage among communities residing in congregate settings.

Public health impact of herpes zoster vaccination on older adults in Singapore: a modeling study.

In Singapore, population aging and rising life expectancy are increasing herpes zoster (HZ) burden, which may be reduced by vaccination. The present study modeled the public health impact of HZ vaccination in Singapore using ZOster ecoNomic Analysis (ZONA) model adapted with Singapore-specific key model inputs, where available. Base case analysis was conducted in adults ≥ 50 years of age (YOA), exploring three vaccination strategies (no vaccination, recombinant zoster vaccine [RZV], zoster vaccine live [ZVL]) under mass vaccination setting (30% coverage). Scenario and sensitivity analyses were performed. Out of 1.51 million adults in 2021 (base case population), 406,513 (27.0%) cases of HZ, 68,264 (4.5%) cases of post-herpetic neuralgia (PHN), and 54,949 (3.6%) cases of other complications were projected without vaccination. RZV was estimated to avoid 73,129 cases of HZ, 11,094 cases of PHN, and 9,205 cases of other complications over the subjects' remaining lifetime; ZVL would avoid 17,565 cases of HZ, 2,781 cases of PHN, and 1,834 cases of other complications. The number needed to vaccinate to prevent one case of HZ/PHN was lower for RZV (7/41) than ZVL (26/163). Among all five age-stratified cohorts (50-59/60-64/65-69/70-79/≥80 YOA), RZV (versus no vaccination/ZVL) avoided the largest number of cases in the youngest cohort, 50-59 YOA. Results were robust under scenario and sensitivity analyses. Mass vaccination with RZV is expected to greatly reduce the public health burden of HZ among Singapore individuals ≥ 50 YOA. Findings support value assessment and decision-making regarding public health vaccination strategies for HZ prevention in Singapore.

Risk of shingles (herpes zoster) increases with age, especially from 50 years. Shingles is a major public health concern in Singapore, given its rapidly aging population. Vaccination can prevent shingles and reduce its public health burden. Two shingles vaccines are available in Singapore: recombinant zoster vaccine (RZV) since 2021, zoster vaccine live (ZVL) since 2008. To understand the value of preventing shingles via vaccination, this study assessed the public health impact of shingles vaccination. Three vaccination strategies (no vaccination, vaccination with RZV, vaccination with ZVL) were compared in 1.51 million Singapore adults aged 50 years and above. Without vaccination, public health burden of shingles would be high; an estimated 406,513 (27.0%) would have shingles, 68,264 (4.5%) would have shingles-related long-term nerve pain, 54,949 (3.6%) would have other shingles-related complications, and 17,762 (1.2%) would be hospitalized due to shingles. Shingles vaccination could reduce this public health burden: RZV avoided 73,129 cases of shingles, 11,094 cases of shingles-related long-term nerve pain, 9,205 cases of other shingles-related complications, and 2,827 hospitalizations due to shingles, which was 4­6 times that avoided with ZVL (shingles: 17,565; shingles-related long-term nerve pain: 2,781; other shingles-related complications: 1,834; hospitalizations due to shingles: 484). Shingles vaccination for adults aged 50 years and above, especially early vaccination from 50­59 years, could reduce its public health burden more than vaccination at later ages and contribute toward healthy aging, preventive care, and the Healthier SG initiative. Results support local public health value assessments and decision-making for shingles prevention.

Evaluating targeted COVID-19 vaccination strategies with agent-based modeling.

We evaluate approaches to vaccine distribution using an agent-based model of human activity and COVID-19 transmission calibrated to detailed trends in cases, hospitalizations, deaths, seroprevalence, and vaccine breakthrough infections in Florida, USA. We compare the incremental effectiveness for four different distribution strategies at four different levels of vaccine supply, starting in late 2020 through early 2022. Our analysis indicates that the best strategy to reduce severe outcomes would be to actively target high disease-risk individuals. This was true in every scenario, although the advantage was greatest for the intermediate vaccine availability assumptions and relatively modest compared to a simple mass vaccination approach under high vaccine availability. Ring vaccination, while generally the most effective strategy for reducing infections, ultimately proved least effective at preventing deaths. We also consider using age group as a practical surrogate measure for actual disease-risk targeting; this approach also outperforms both simple mass distribution and ring vaccination. We find that quantitative effectiveness of a strategy depends on whether effectiveness is assessed after the alpha, delta, or omicron wave. However, these differences in absolute benefit for the strategies do not change the ranking of their performance at preventing severe outcomes across vaccine availability assumptions.

Temporal trends and spatial clusters of high risk for maternal death due to COVID-19 pre and during COVID-19 vaccination in Brazil: a national population-based ecological study.

OBJECTIVE: This study comprehensively analyzed the temporal and spatial dynamics of COVID-19 cases and deaths within the obstetric population in Brazil, comparing the periods before and during mass COVID-19 vaccination. We explored the trends and geographical patterns of COVID-19 cases and maternal deaths over time. We also examined their correlation with the SARS-CoV-2 variant circulating and the social determinants of health. STUDY DESIGN: This is a nationwide population-based ecological study. METHODS: We obtained data on COVID-19 cases, deaths, socioeconomic status, and vulnerability information for Brazil's 5570 municipalities for both the pre-COVID-19 vaccination and COVID-19 vaccination periods. A Bayesian model was used to mitigate indicator fluctuations. The spatial correlation of maternal cases and fatalities with socioeconomic and vulnerability indicators was assessed using bivariate Moran. RESULTS: From March 2020 to June 2023, a total of 23,823 cases and 1991 maternal fatalities were recorded among pregnant and postpartum women. The temporal trends in maternal incidence and mortality rates fluctuated over the study period, largely influenced by widespread COVID-19 vaccination and the dominant SARS-CoV-2 variant. There was a significant reduction in maternal mortality due to COVID-19 following the introduction of vaccination. The geographical distribution of COVID-19 cases and maternal deaths exhibited marked heterogeneity in both periods, with distinct spatial clusters predominantly observed in the North, Northeast, and Central West regions. Municipalities with the highest Human Development Index reported the highest incidence rates, while those with the highest levels of social vulnerability exhibited elevated mortality and fatality rates. CONCLUSION: Despite the circulation of highly transmissible variants of concern, maternal mortality due to COVID-19 was significantly reduced following the mass vaccination. There was a heterogeneous distribution of cases and fatalities in both periods (before and during mass vaccination). Smaller municipalities and those grappling with social vulnerability issues experienced the highest rates of maternal mortality and fatalities.

Optimizing the Selection of Mass Vaccination Sites: Access and Equity Consideration.

In the early phases of the COVID-19 pandemic, vaccine accessibility was limited, impacting large metropolitan areas such as Los Angeles County, which has over 10 million residents but only nine initial vaccination sites, which resulted in people experiencing long travel times to get vaccinated. We developed a mixed-integer linear model to optimize site selection, considering equitable access for vulnerable populations. Analyzing 277 zip codes between December 2020 and May 2021, our model incorporated factors such as car ownership, ethnic group disease vulnerability, and the Healthy Places Index, alongside travel times by car and public transit. Our optimized model significantly outperformed actual site allocations for all ethnic groups. We observed that White populations faced longer travel times, likely due to their residences being in more remote, less densely populated areas. Conversely, areas with higher Latino and Black populations, often closer to the city center, benefited from shorter travel times in our model. However, those without cars experienced greater disadvantages. While having many vaccination sites might improve access for those dependent on public transit, that advantage is diminished if people must search among many sites to find a location with available vaccines.

BCG is protective against death in male but not female patients with pulmonary tuberculosis in Guinea-Bissau.

BACKGROUND: Growing evidence supports the existence of a sex difference in immunity to tuberculosis (TB). This is most often to the detriment of males. This study aimed to assess the association between scar size from bacillus Calmette-Guérin (BCG) and mortality risk stratified by sex. METHODS: Kaplan-Meier survivor functions and Cox proportional hazard models were used to assess mortality risk by sex and scar size. Groups were further compared by clinical and epidemiological characteristics. RESULTS: Between 2003 and 2019, 2944 eligible patients were identified, of whom 1003 were included in the final analysis. Males with BCG scars, particularly large scars, were less likely to die within 1 y of diagnosis than males with no scar (adjusted hazard ratio 0.36 [95% confidence interval 0.15 to 0.88]). In contrast, females with small scars trended towards higher mortality than females with no scars or females with large scars. CONCLUSIONS: BCG protects against death in male but not female patients with TB. More research is needed to determine the mechanisms underpinning these sex differences and whether they are generalizable beyond this setting.

Analysis of COVID-19 Risk Following a Ring Vaccination Intervention to Address SARS-CoV-2 Alpha Variant Transmission in Montreal, Canada.

Importance: Given limited COVID-19 vaccine availability early in the pandemic, optimizing immunization strategies was of paramount importance. Ring vaccination has been used successfully to control transmission of other airborne respiratory viruses. Objective: To assess the association of a ring vaccination intervention on COVID-19 spread in the initial epicenter of SARS-CoV-2 Alpha variant transmission in Montreal, Canada. Design, Setting, and Participants: This cohort study compared COVID-19 daily disease risk in 3 population-based groups of neighborhoods in Montreal, Canada, defined by their intervention-specific vaccine coverage at the neighborhood level: the primary intervention group (500 or more vaccinated persons per 10 000 persons), secondary intervention group (95 to 499), and control group (0 to 50). The groups were compared within each of 3 time periods: before intervention (December 1, 2020, to March 16, 2021), during and immediately after intervention (March 17 to April 17, 2021), and 3 weeks after the intervention midpoint (April 18 to July 18, 2021). Data were analyzed between June 2021 and November 2021. Exposures: Vaccination targeted parents and teachers of children attending the 32 schools and 48 childcare centers in 2 adjacent neighborhoods with highest local transmission (case counts) of Alpha variant shortly after its introduction. Participants were invited to receive 1 dose of mRNA vaccine between March 22 and April 9, 2021 (before vaccine was available to these age groups). Main Outcomes and Measures: COVID-19 risk in 3 groups of neighborhoods based on intervention-specific vaccine coverage. Results: A total of 11 794 residents were immunized, with a mean (SD) age of 43 (8) years (range, 16-93 years); 5766 participants (48.9%) lived in a targeted neighborhood, and 9784 (83.0%) were parents. COVID-19 risk in the primary intervention group was significantly higher than in the control group before (unadjusted risk ratio [RR], 1.58; 95% CI 1.52-1.65) and during (RR, 1.63; 95% CI, 1.52-1.76) intervention, and reached a level similar to the other groups in the weeks following the intervention (RR, 1.03; 95% CI, 0.94-1.12). A similar trend was observed when restricting to SARS-CoV-2 variants and persons aged 30 to 59 years (before: RR, 1.72; 95% CI, 1.63-1.83 vs after: RR, 1.01; 95% CI, 0.88-1.17). Conclusions and Relevance: Our findings show that ring vaccination was associated with a reduction in COVID-19 risk in areas with high local transmission of Alpha variant shortly after its introduction. Ring vaccination may be considered as an adjunct to mass immunization to control transmission in specific areas, based on local epidemiology.

Taking a machine learning approach to optimize prediction of vaccine hesitancy in high income countries.

Understanding factors driving vaccine hesitancy is crucial to vaccination success. We surveyed adults (N = 2510) from February to March 2021 across five sites (Australia = 502, Germany = 516, Hong Kong = 445, UK = 512, USA = 535) using a cross-sectional design and stratified quota sampling for age, sex, and education. We assessed willingness to take a vaccine and a comprehensive set of putative predictors. Predictive power was analysed with a machine learning algorithm. Only 57.4% of the participants indicated that they would definitely or probably get vaccinated. A parsimonious machine learning model could identify vaccine hesitancy with high accuracy (i.e. 82% sensitivity and 79-82% specificity) using 12 variables only. The most relevant predictors were vaccination conspiracy beliefs, various paranoid concerns related to the pandemic, a general conspiracy mentality, COVID anxiety, high perceived risk of infection, low perceived social rank, lower age, lower income, and higher population density. Campaigns seeking to increase vaccine uptake need to take mistrust as the main driver of vaccine hesitancy into account.