Seasonal influenza vaccination in the Americas: Progress and challenges during the COVID-19 pandemic.

BACKGROUND: Vaccination is one of the most effective measures to prevent influenza illness and its complications; influenza vaccination remained important during the COVID-19 pandemic to prevent additional burden on health systems strained by COVID-19 demand. OBJECTIVES: We describe policies, coverage, and progress of seasonal influenza vaccination programs in the Americas during 2019-2021 and discuss challenges in monitoring and maintaining influenza vaccination coverage among target groups during the COVID-19 pandemic. METHODS: We used data on influenza vaccination policies and vaccination coverage reported by countries/territories via the electronic Joint Reporting Form on Immunization (eJRF) for 2019-2021. We also summarized country vaccination strategies shared with PAHO. RESULTS: As of 2021, 39 (89 %) out of 44 reporting countries/territories in the Americas had policies for seasonal influenza vaccination. Countries/territories adapted health services and immunization delivery strategies using innovative approaches, such as new vaccination sites and expanded schedules, to ensure continuation of influenza vaccination during the COVID-19 pandemic. However, among countries/territories that reported data to eJRF in both 2019 and 2021, median coverage decreased; the percentage point decrease was 21 % (IQR = 0-38 %; n = 13) for healthcare workers, 10 % (IQR = -1.5-38 %; n = 12) for older adults, 21 % (IQR = 5-31 %; n = 13) for pregnant women, 13 % (IQR = 4.8-20.8 %; n = 8) for persons with chronic diseases, and 9 % (IQR = 3-27 %; n = 15) for children. CONCLUSIONS: Countries/territories in the Americas successfully adapted influenza vaccination delivery to continue vaccination services during the COVID-19 pandemic; however, reported influenza vaccination coverage decreased from 2019 to 2021. Reversing declines in vaccination will necessitate strategic approaches that prioritize sustainable vaccination programs across the life course. Efforts should be made to improve the completeness and quality of administrative coverage data. Lessons learned from COVID-19 vaccination, such as the rapid development of electronic vaccination registries and digital certificates, might facilitate advances in coverage estimation.

Estimating global and regional between-country inequality in routine childhood vaccine coverage in 195 countries and territories from 2019 to 2021: a longitudinal study.

Background: Global routine childhood vaccine coverage has plateaued in recent years, and the COVID-19 pandemic further disrupted immunisation services. We estimated global and regional inequality of routine childhood vaccine coverage from 2019 to 2021, particularly assessing the impacts of the COVID-19 pandemic. Methods: We used longitudinal data for 11 routine childhood vaccines from the WHO-UNICEF Estimates of National Immunization Coverage (WUENIC), including 195 countries and territories in 2019-2021. The slope index of inequality (SII) and relative index of inequality (RII) of each vaccine were calculated through linear regression to express the difference in coverage between the top and bottom 20% of countries at the global and regional levels. We also explored inequalities of routine childhood vaccine coverage by WHO regions and unvaccinated children by income groups. Findings: Globally between January 1, 2019 and December 31, 2021, most childhood vaccines showed a declining trend in coverage, and therefore an increasing number of unvaccinated children, especially in low-income and lower-middle-income countries. Between-country inequalities existed for all 11 routine childhood vaccine coverage indicators. The SII for the third dose of diphtheria-tetanus-pertussis-containing vaccine (DTP3) coverage was 20.1 percentage points (95% confidence interval: 13.7, 26.5) in 2019, and rose to 23.6 (17.5, 30.0) in 2020 and 26.9 (20.0, 33.8) in 2021. Similar patterns were found for RII results and in other routine vaccines. In 2021, the second dose of measles-containing vaccine (MCV2) coverage had the highest global absolute inequality (31.2, [21.5-40.8]), and completed rotavirus vaccine (RotaC) coverage had the lowest (7.8, [-3.9, 19.5]). Among six WHO regions, the European Region consistently had the lowest inequalities, and the Western Pacific Region had the largest inequalities for many indicators, although both increased from 2019 to 2021. Interpretation: Global and regional inequalities of routine childhood vaccine coverage persisted and substantially increased from 2019 to 2021. These findings reveal economic-related inequalities by vaccines, regions, and countries, and underscore the importance of reducing such inequalities. These inequalities were widened during the COVID-19 pandemic, resulting in even lower coverage and more unvaccinated children in low-income countries. Funding: Bill & Melinda Gates Foundation.

Increasing polio coverage with safer vaccines: a pressing need in Latin America

Given the actual risk of poliomyelitis outbreaks in the region due to poliovirus derived from the Sabin vaccine or the importation of wild poliovirus, the Latin American Society of Pediatric Infectious Diseases commissioned an ad hoc group of experts from the institution's Vaccines and Biologicals Committee, to draft an official position paper on the urgent need to increase immunization levels against the disease in the region and incorporate inactivated polio vaccine exclusive schedules in all national immunization programs. This publication discusses the main conclusions and recommendations generated as a result of such activity.Copyright © 2022, Sociedad Chilena de Infectologia. All rights reserved.

Vaccine Mandates in the COVID-19 Era: Changing Paradigm or Public Health Opportunity? Comment on "Convergence on Coercion: Functional and Political Pressures as Drivers of Global Childhood Vaccine Mandates”

The debate around vaccine mandates has flourished over the last decade, with several countries introducing or extending mandatory childhood vaccinations. In a recent study, Attwell and Hannah explore how functional and political pressures added to public health threats in selected countries, motivating governments to increase the coerciveness of their childhood vaccine regimes. In this commentary, we reflect on whether such model applies to the coronavirus disease 2019 (COVID-19) case and how the pandemic has re-shuffled the deck around vaccine mandates. We identify COVID-19 immunisation policies' distinctive aspects as we make the case of countries implementing mass immunisation programmes while relying on digital COVID-19 certificates as an indirect form of mandate to increase vaccine uptake. We conclude by acknowledging that different forms of mandatory vaccination might serve as a shortcut to protect population health in times of emergency, underlining, however, that the ultimate public health goal is to promote voluntary, informed, and responsible adherence to preventive behaviours. © 2023 The Author(s);Published by Kerman University of Medical Sciences.

A Comparative Analysis on the Social Determinants of COVID-19 Vaccination Coverage in Fragile and Conflict Affected Settings and Non-fragile and Conflict Affected Settings.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has coerced various resources of all the countries. While the high-income nations redirected financial and human resources to understand specific determinants of vaccination coverage, fragile and conflict-affected setting (FCS) nations were waiting for global bodies to cater to their ever-growing need for vaccines and other lifesaving drugs. This study aimed to determine various factors influencing vaccine coverage in the FCS context. METHODS: World Bank's classification of FCS states was the primary source for country classification. The study utilized data from various other open sources. The study models cross-country inequities in COVID-19 vaccine coverage and we have employed multi-variate log-linear regressions to understand the relationship between COVID-19 vaccine coverage and cross-country macro-level determinants. The analysis was conducted on two samples, non-FCS Countries and the FCS countries. RESULTS: Socio-economic determinants such as gross domestic product (GDP) per capita, socioeconomic resilience; health system determinants such as density of human resources, government spending on health expenditure; and political determinants such as effective government, more power to regional governments, political stability and absence of violence play a pivotal role in vaccine coverage. We also found that FCS countries with a higher share of people strongly believing in the vaccine effectiveness have a positive association with COVID-19 vaccine coverage. CONCLUSION: The study confirmed that political factors, government effectiveness and political stability are also important determinants of vaccine coverage. The result further draws attention to few policy implications such as promoting future research to explore the linkages between the perceived equality before the law and individual liberty and its effect on vaccination coverage in the FCS.

Active medical recommendation is the best tool for increasing influenza vaccine coverage in healthy adult workers

Introduction In Spain, influenza vaccination is available in companies free of charge for their workers. Despite this, vaccination coverage against influenza is very low in these groups. Objectives The aim of this work is to know the reasons for acceptance of influenza vaccination in a working population. Methods During the 2021–2022 influenza vaccination campaign, we conducted a survey of two groups of workers at the automobile factories of RENAULT ESPAÑA S.A. in the cities of Valladolid and Palencia (Spain). The first group (NV) was formed by 304 (33.5%) workers who did not receive the influenza vaccine in the previous season. The second (V) was formed by 604 workers (66.5%) who had been vaccinated against influenza at least the previous season. In the NV group, they were asked the reasons why they did not get vaccinated the previous season and if they did so in 2021–2022. In group V, only the reasons for continuing to be vaccinated were asked. Results In NV, the main reason for avoiding vaccination in the previous season was the lack of perception of the severity of the influenza infection (74.7%), and 31.6% and 29.0% of them decided to get vaccinated during the 2021–2022 season due to the fear of co-infection of SARS-CoV-2 and influenza and medical recommendations respectively. The 83.5% of group V responded that the reason for getting vaccinated in 2021–2022 was their adherence to vaccination. Conclusions The results show that medical recommendation is the best tool to vaccinate workers against influenza and make them adhere to it. Also, the fear to co-infection of COVID-19 and flu was a frequent reason for getting vaccinated, above all in NV. Resumen Introducción En España la vacunación antigripal está disponible en las empresas de manera gratuita para sus trabajadores. A pesar de esto, las coberturas vacunales frente a la gripe son muy bajas en estos grupos. Objetivos El objetivo es conocer los motivos de aceptación de la vacunación antigripal en la población trabajadora. Métodos Durante la campaña de vacunación de gripe 2021–2022 realizamos una encuesta a dos grupos de trabajadores de las factorías automovilísticas de RENAULT ESPAÑA S.A. en las ciudades de Valladolid y Palencia. El primer grupo (NV) estuvo formado por 304 (33,5%) trabajadores que no recibieron la vacuna antigripal la temporada anterior. El segundo (V) estaba formado por 604 trabajadores (66,5%) que habían sido vacunados contra la gripe al menos la temporada anterior. En el grupo NV se les preguntó las razones de porque no se vacunaron la temporada anterior y si lo hicieron en 2021–2022. En el grupo V se preguntó únicamente las razones para seguirse vacunando. Resultados En NV, la principal razón para evitar la vacunación en la temporada anterior fue la falta de percepción de la gravedad de la gripe (74,7%), y el 31,6% y 29,0% de ellos decidió vacunarse durante la temporada 2021–2022 por el miedo a la co-infección del SARS-Cov-2 y gripe y a las recomendaciones médicas respectivamente. El 83,5% del grupo V respondió que el motivo de vacunarse en el 2021–2022 fue su adherencia a la vacunación. Conclusiones Los resultados muestran que la recomendación médica es la mejor herramienta para vacunar frente a la gripe a los trabajadores y hacerles adherentes a la misma. También, el miedo a la co-infección de COVID-19 y gripe fue una de las razones más frecuentes para vacunarse, sobre todo en NV.

Covid-19 vaccination uptake by Hapu Mama - How are we progressing?

The Covid-19 vaccine has been recommended for pregnant people (hapu mama) in Aotearoa New Zealand since June 2021. We surveyed people birthing in a tertiary hospital regarding their vaccination status and reasons for this. There were 74% (142/191) of pregnant people who were fully vaccinated. Motivators for vaccination included protection against Covid-19 and antibody transfer to the baby (pepe). Unvaccinated participants worried about vaccine safety. Concerns were raised about the change in official advice without well-communicated reasons for the change. Future vaccine and booster rollouts must be delivered equitably and hapu mama must be a priority group.Copyright © 2022 The Authors. Australian and New Zealand Journal of Obstetrics and Gynaecology published by John Wiley & Sons Australia, Ltd on behalf of Royal Australian and New Zealand College of Obstetricians and Gynaecologists. © 2022 The Authors. Australian and New Zealand Journal of Obstetrics and Gynaecology published by John Wiley & Sons Australia, Ltd on behalf of Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

Without Risk: A Social Analysis of the Vaccination Programme in England

In this chapter, we examine the social forces shaping the design and delivery of the COVID-19 vaccination programme in England. Looking beyond direct inclusion or exclusion in policy decision-making, we view health and health care as an arena containing several powerful interest groups. Our approach considers the influences, interests, and strategies that can work to reshape, constrain, challenge, or reject policy —though we also consider if and how actors might collaborate or develop alliances and allegiances that support and facilitate policy. We analyse these dynamics in the context of various dimensions of the COVID-19 vaccination programme in England (in relation to supply and manufacturing, regulation, prioritisation, vaccine nationalism, and vaccine coverage). Overall, we argue that, though there were examples of actors working to challenge or reject policy and decision-making in the development and delivery of the vaccination programme, there were limited impacts on or resulting changes to policy—particularly where this was counter to the interests of government and/or the pharmaceutical industry. Additionally, groups have to a greater extent acted and collaborated in a manner that has been supportive and facilitative of policy. © TheEditor(s) (ifapplicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021, 2022.

Active medical recommendation is the best tool for increasing influenza vaccine coverage in healthy adult workers

Introduction: In Spain, influenza vaccination is available in companies free of charge for their workers. Despite this, vaccination coverage against influenza is very low in these groups. Objective(s): The aim of this work is to know the reasons for acceptance of influenza vaccination in a working population. Method(s): During the 2021-2022 influenza vaccination campaign, we conducted a survey of two groups of workers at the automobile factories of RENAULT ESPANA S.A. in the cities of Valladolid and Palencia (Spain). The first group (NV) was formed by 304 (33.5%) workers who did not receive the influenza vaccine in the previous season. The second (V) was formed by 604 workers (66.5%) who had been vaccinated against influenza at least the previous season. In the NV group, they were asked the reasons why they did not get vaccinated the previous season and if they did so in 2021-2022. In group V, only the reasons for continuing to be vaccinated were asked. Result(s): In NV, the main reason for avoiding vaccination in the previous season was the lack of perception of the severity of the influenza infection (74.7%), and 31.6% and 29.0% of them decided to get vaccinated during the 2021-2022 season due to the fear of co-infection of SARS-CoV-2 and influenza and medical recommendations respectively. The 83.5% of group V responded that the reason for getting vaccinated in 2021-2022 was their adherence to vaccination. Conclusion(s): The results show that medical recommendation is the best tool to vaccinate workers against influenza and make them adhere to it. Also, the fear to co-infection of COVID-19 and flu was a frequent reason for getting vaccinated, above all in NV.Copyright © 2023

Coverage of primary and booster vaccination against COVID-19 by socioeconomic level: A nationwide cross-sectional registry study.

High and equitable COVID-19 vaccination coverage is important for pandemic control and prevention of health inequity. However, little is known about socioeconomic correlates of booster vaccination coverage. In this cross-sectional study of all Norwegian adults in the national vaccination program (N = 4,190,655), we use individual-level registry data to examine coverage by levels of household income and education of primary (≥2 doses) and booster (≥3 doses) vaccination against COVID-19. We stratify the analyses by age groups with different booster recommendations and report relative risk ratios (RR) for vaccination by 25 August 2022. In the 18-44 y group, individuals with highest vs. lowest education had 94% vs. 79% primary coverage (adjusted RR (adjRR) 1.15, 95%CI 1.14-1.15) and 67% vs. 38% booster coverage (adjRR 1.55, 95% CI 1.55-1.56), while individuals with highest vs. lowest income had 94% vs. 81% primary coverage (adjRR 1.10, 95%CI 1.10-1.10) and 60% vs. 43% booster coverage (adjRR 1.23, 95%CI 1.22-1.24). In the ≥45 y group, individuals with highest vs. lowest education had 96% vs. 92% primary coverage (adjRR 1.02, 95%CI 1.02-1.02) and 88% vs. 80% booster coverage (adjRR 1.09, 95%CI 1.09-1.09), while individuals with highest vs. lowest income had 98% vs. 82% primary coverage (adjRR 1.16, 95%CI 1.16-1.16) and 92% vs. 64% booster coverage (adjRR 1.33, 95%CI 1.33-1.34). In conclusion, we document large socioeconomic inequalities in COVID-19 vaccination coverage, especially for booster vaccination, even though all vaccination was free-of-charge. The results highlight the need to tailor information and to target underserved groups for booster vaccination.

COVID-19 vaccine inequity in African low-income countries.

Equitable access and utilization of the COVID-19 vaccine is the main exit strategy from the pandemic. This paper used proceedings from the Second Extraordinary Think-Tank conference, which was held by the Health Economics and Policy Unit at the Kamuzu University of Health Sciences in collaboration with the Malawi Ministry of Health, complemented by a review of literature. We found disparities in COVID-19 vaccine coverage among low-income countries. This is also the case among high income countries. The disparities are driven mainly by insufficient supply, inequitable distribution, limited production of the vaccine in low-income countries, weak health systems, high vaccine hesitancy, and vaccine misconceptions. COVID-19 vaccine inequity continues to affect the entire world with the ongoing risks of emergence of new COVID-19 variants, increased morbidity and mortality and social and economic disruptions. In order to reduce the COVID-19 vaccination inequality in low-income countries, there is need to expand COVAX facility, waive intellectual property rights, transform knowledge and technology acquired into vaccines, and conduct mass COVID-19 vaccination campaigns.

COVID-19 vaccination coverage in Egypt: a large-scale national survey - to help achieving vaccination target, March-May, 2022.

BACKGROUND: Only 57 countries have vaccinated 70% of their population against COVID-19, most of them in high-income countries, whereas almost one billion people in low-income countries remained unvaccinated. In March-May 2022, Egypt's Ministry of Health and Population (MoHP) conducted a nationwide community-based survey to determine COVID-19 vaccine coverage and people's perceptions of vaccination in order to improve COVID-19 vaccination uptake and confidence among Egyptians, as well as to prioritize interventions. METHODS: A cross-sectional population-based household survey among Egyptians ≥ 18 years of age was implemented in two phases using a multistage random sampling technique in all of Egypt's 27 governorates. A sample of 18,000 subjects divided into 450 clusters of 20 households each was calculated in proportion to each governorate and the main occupation of the population. Participants were interviewed using a semistructured questionnaire that included demographics, vaccination information from the vaccination card, history of COVID-19 infection, reasons for vaccine refusal among the unvaccinated, and vaccination experience among vaccinated subjects. Vaccination coverage rates were calculated by dividing numbers by the total number of participants. Bivariate and multivariate analyses were performed by comparing the vaccinated and unvaccinated to identify the risk factors for low vaccine uptake. RESULTS: Overall 18,107 were interviewed, their mean age was 42 ± 16 years and 58.8% were females. Of them, 8,742 (48.3%) had COVID-19 vaccine and 8,020 (44.3%) were fully vaccinated. Factors associated with low vaccination uptake by multivariate analysis included: age groups (18-29 and 30-39) (ORs 2.0 (95% C.I. 1.8-2.2) and 1.3 (95% C.I.1.2-1.4), respectively), residences in urban or frontier governorates (ORs 1.6 (95% C.I. 1.5-1.8) and 1.2 (95% C.I. 1.1-1.4), respectively), housewives and self-employed people (ORs 1.3 (95% C.I. 1.2-1.4) and 1.2 (95% C.I. 1.1-1.4), respectively), married people (ORs 1.3 (95% C.I. 1.2-1.4), and primary and secondary educated (ORs 1.1 (95% C.I. 1.01-1.2) and 1.1(1.04-1.2) respectively). Vaccine hesitancy was due to fear of adverse events (17.5%), mistrust of vaccine (10.2%), concern over safety during pregnancy and lactation (6.9%), and chronic diseases (5.0%). CONCLUSIONS: Survey identified lower vaccination coverage in Egypt compared to the WHO 70% target. Communication programs targeting the groups with low vaccine uptake are needed to eliminate barriers related to vaccination convenience, side effects, and safety to effectively promote vaccine uptake. Findings from the survey could contribute significantly to vaccination promotion by guiding decision-making efforts on the risky groups and preventing vaccine hesitancy.

Childhood immunization coverage during the COVID-19 pandemic in the province of Siracusa, Italy.

Introduction: The COVID-19 pandemic has severely impacted routine immunization activities and a decline in vaccination coverage has been documented around the world. The aim of this study was to assess the impact of the direct and indirect effects of the COVID-19 pandemic on routine childhood vaccination coverage in the Province of Siracusa, Italy. Methods: We compared 2020 and 2019 vaccination coverage by age group and vaccine type. Results were considered statistically significant at a two-tailed p-value ≤ 0.05. Results: Our findings show that vaccination coverage rates for mandatory and recommended vaccinations decreased in 2020 compared with the previous year (range from -1.4% to -7.8%). Anti-rotavirus vaccination increased (+4.8%, as compared to 2019), while the reductions observed for polio vaccination (hexavalent) and human papillomavirus vaccination in males were not statistically significant. The reduction did not hit the population in the same manner, with the greater decreases observed for children aged > 24 months compared to the younger (-5.7% vs -2.2%) and for booster doses compared to the primary vaccinations (-6.4% vs -2.6%). Conclusions: This study found that vaccination coverage of routine childhood immunisations was negatively affected during the COVID-19 pandemic in the Province of Siracusa. It is of huge importance to put in place some catch-up programs to ensure vaccinations at the earliest of individuals who missed immunization during the pandemic.

Population-Level Relative Effectiveness of the COVID-19 Vaccines and the Contribution of Naturally Acquired Immunity.

BACKGROUND: Immune protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be induced by natural infection or vaccination or both. Interaction between vaccine-induced immunity and naturally acquired immunity at the population level has been understudied. METHODS: We used regression models to evaluate whether the impact of coronavirus disease 2019 (COVID-19) vaccines differed across states with different levels of naturally acquired immunity from March 2021 to April 2022 in the United States. Analysis was conducted for 3 evaluation periods separately (Alpha, Delta, and Omicron waves). As a proxy for the proportion of the population with naturally acquired immunity, we used either the reported seroprevalence or the estimated proportion of the population ever infected in each state. RESULTS: COVID-19 mortality decreased as coverage of ≥1 dose increased among people ≥65 years of age, and this effect did not vary by seroprevalence or proportion of the total population ever infected. Seroprevalence and proportion ever infected were not associated with COVID-19 mortality, after controlling for vaccine coverage. These findings were consistent in all evaluation periods. CONCLUSIONS: COVID-19 vaccination was associated with a sustained reduction in mortality at state level during the Alpha, Delta, and Omicron periods. The effect did not vary by naturally acquired immunity.

Estimating the impact of influenza vaccination of low-risk 50-64-year-olds on acute and ICU hospital bed usage in an influenza season under endemic COVID-19 in the UK.

Co-circulation of influenza and SARS-CoV-2 has the potential to place considerable strain on health-care services. We estimate the cost-effectiveness and health-care resource utilization impacts of influenza vaccination of low-risk 50-64-y-olds in the United Kingdom (UK) against a background SARS-CoV-2 circulation. A dynamic susceptible-exposed-infected-recovered model was used to simulate influenza transmission, with varying rates of vaccine coverage in the low-risk 50-64 y age-group. Four scenarios were evaluated: no vaccination (baseline), 40%, 50%, and 60% coverage. For the 50% and 60% coverage, this rate was also applied to high-risk 50-64-y-olds, whereas 48.6% was used for the baseline and 40% coverage scenarios. Cost-effectiveness was estimated in terms of humanistic outcomes and incremental cost-effectiveness ratio (ICER), with discounting applied at 3%. Overall, influenza vaccination of 50-64-y-olds resulted in reductions in GP visits, hospitalizations, and deaths, with a reduction in influenza-related mortality of 34%, 41%, and 52% for 40%, 50%, and 60% coverage, respectively. All four scenarios resulted in acute and intensive care unit (ICU) bed occupancy levels above available capacity, although vaccination of low-risk 50-64-y-olds resulted in a 35-54% and 16-25% decrease in excess acute and ICU bed requirements, respectively. Vaccination of this group against influenza was highly cost-effective from the payer perspective, with ICERs of £2,200-£2,343/quality-adjusted life year across the coverage rates evaluated. In conclusion, in the UK, vaccination of low-risk 50-64-y-olds against influenza is cost-effective and can aid in alleviating bed shortages in a situation where influenza and SARS-CoV-2 are co-circulating.

Update on the effectiveness of COVID-19 vaccines on different variants of SARS-CoV-2.

It has been more than three years since the first emergence of coronavirus disease 2019 (COVID-19) and millions of lives have been taken to date. Like most pandemics caused by viral infections, massive public vaccination is the most promising approach to cease COVID-19 infection. In this regard, several vaccine platforms including inactivated virus, nucleic acid-based (mRNA and DNA vaccines), adenovirus-based, and protein-based vaccines have been designed and developed for COVID-19 prevention and many of them have received FDA or WHO approval. Fortunately, after global vaccination, the transmission rate, disease severity, and mortality rate of COVID-19 infection have diminished significantly. However, a rapid increase in COVID-19 cases due to the omicron variant in vaccinated countries has raised concerns about the effectiveness of these vaccines. In this review, articles published between January 2020 and January 2023 were reviewed using PubMed, Google Scholar, and Web of Science search engines with appropriate related keywords. The related papers were selected and discussed in detail. The current review mainly focuses on the effectiveness and safety of COVID-19 vaccines against SARS-CoV-2 variants. Along with discussing the available and approved vaccines, characteristics of different variants of COVID-19 have also been discussed in brief. Finally, the currently circulating COVID-19 variant i.e Omicron, along with the effectiveness of available COVID-19 vaccines against these new variants are discussed in detail. In conclusion, based on the available data, administration of newly developed bivalent mRNA COVID-19 vaccines, as booster shots, would be crucial to prevent further circulation of the newly developed variants.

Mitigating co-circulation of seasonal influenza and COVID-19 pandemic in the presence of vaccination: A mathematical modeling approach.

The co-circulation of two respiratory infections with similar symptoms in a population can significantly overburden a healthcare system by slowing the testing and treatment. The persistent emergence of contagious variants of SARS-CoV-2, along with imperfect vaccines and their waning protections, have increased the likelihood of new COVID-19 outbreaks taking place during a typical flu season. Here, we developed a mathematical model for the co-circulation dynamics of COVID-19 and influenza, under different scenarios of influenza vaccine coverage, COVID-19 vaccine booster coverage and efficacy, and testing capacity. We investigated the required minimal and optimal coverage of COVID-19 booster (third) and fourth doses, in conjunction with the influenza vaccine, to avoid the coincidence of infection peaks for both diseases in a single season. We show that the testing delay brought on by the high number of influenza cases impacts the dynamics of influenza and COVID-19 transmission. The earlier the peak of the flu season and the greater the number of infections with flu-like symptoms, the greater the risk of flu transmission, which slows down COVID-19 testing, resulting in the delay of complete isolation of patients with COVID-19 who have not been isolated before the clinical presentation of symptoms and have been continuing their normal daily activities. Furthermore, our simulations stress the importance of vaccine uptake for preventing infection, severe illness, and hospitalization at the individual level and for disease outbreak control at the population level to avoid putting strain on already weak and overwhelmed healthcare systems. As such, ensuring optimal vaccine coverage for COVID-19 and influenza to reduce the burden of these infections is paramount. We showed that by keeping the influenza vaccine coverage about 35% and increasing the coverage of booster or fourth dose of COVID-19 not only reduces the infections with COVID-19 but also can delay its peak time. If the influenza vaccine coverage is increased to 55%, unexpectedly, it increases the peak size of influenza infections slightly, while it reduces the peak size of COVID-19 as well as significantly delays the peaks of both of these diseases. Mask-wearing coupled with a moderate increase in the vaccine uptake may mitigate COVID-19 and prevent an influenza outbreak.

Movement restrictions, vaccine coverage, and reduction of the COVID-19 incidence rate in the fourth wave of the pandemic: Analysis results from 63 provinces in Vietnam.

On April 27, 2021, the fourth wave of the coronavirus disease 2019 (COVID-19) pandemic originating from the Delta variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began in Vietnam. The adoption of travel restrictions, coupled with rapid vaccination and mask-wearing, is a global strategy to prevent the spread of COVID-19. Although trade-off between health and economic development are unavoidable in this situation, little evidence that is specific to Vietnam in terms of movement restrictions, vaccine coverage, and real-time COVID-19 cases is available. Our research question is whether travel restrictions and vaccine coverage are related to changes in the incidence of COVID-19 in each province in Vietnam. We used Google's Global Mobility Data Source, which reports different mobility types, along with reports of vaccine coverage and COVID-19 cases retrieved from publicly and freely available datasets, for this research. Starting from the 50th case per province and incorporating a 14-day period to account for exposure and illness, we examined the association between changes in mobility (from day 27 to 04-03/11/2021) and the ratio of the number of new confirmed cases on a given day to the total number of cases in the past 14 days of indexing (the potentially contagious group in the population) per million population by making use of LOESS regression and logit regression. In two-thirds of the surveyed provinces, a reduction of up to 40% in commuting movement (to the workplace, transit stations, grocery stores, and entertainment venues) was related to a reduction in the number of cases, especially in the early stages of the pandemic. Once both movement and disease prevalence had been mitigated, further restrictions offered little additional benefit. These results indicate the importance of early and decisive actions during the pandemic.

Infectivity of Omicron BA.5 Comparison with Original Strain and Other Mutated Strain of SARS-CoV-2 in Japan

Background: Earlier studies have indicated the BA.5 sublineage of Omicron variant strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as more infective than BA.2. Object: This study estimated BA.5 infectivity while controlling other factors possibly affecting BA.5 infectivity including vaccine effectiveness, waning effectiveness, other mutated strains, Olympic Games, and countermeasures. Method: The effective reproduction number R(t) was regressed on shares of BA.5 and vaccine coverage, vaccine coverage with some delay, temperature, humid-ity, mobility, shares of other mutated strains, counter-measures including the Go to Travel Campaign, and the Olympic Games and associated countermeasures. The study period was February 2020–July 22, 2022, using data available on August 12, 2022. Results: A 120 day lag was assumed to assess waning. Mobil-ity, some states of emergency, vaccine coverage and those with lag, and the Delta and Omicron BA.2 pro-portions were found to be significant. The omicron BA.1 proportion was significant, but with an unex-pected sign. The estimated coefficient of BA.5 was negative but not significant. The Go to Travel Campaign was significantly negative, indicating reduced infectiv-ity. The Olympic Games were negative but not sig-nificant, indicating that they did not raise infectivity. Discussion: The obtained estimated results show that BA.5 did not have higher infectivity than the original strain. It was lower than either Delta or Omicron BA.2 variant strains. That finding might be inconsis-tent with results obtained from earlier studies. This study controlled several factors potentially affecting R(t), though the earlier studies did not. Therefore, results from this study might be more reliable than those of earlier studies. © Fuji Technology Press Ltd.

Temporal trends and determinants of COVID-19 vaccine coverage and series initiation during pregnancy in Ontario, Canada, December 2020 to December 2021: A population-based retrospective cohort study.

BACKGROUND: Population-based COVID-19 vaccine coverage estimates among pregnant individuals are limited. We assessed temporal patterns in vaccine coverage (≥1 dose before or during pregnancy) and evaluated factors associated with vaccine series initiation (receiving dose 1 during pregnancy) in Ontario, Canada. METHODS: We linked the provincial birth registry with COVID-19 vaccination records from December 14, 2020 to December 31, 2021 and assessed coverage rates among all pregnant individuals by month, age, and neighborhood sociodemographic characteristics. Among individuals who gave birth since April 2021-when pregnant people were prioritized for vaccination-we assessed associations between sociodemographic, behavioral, and pregnancy-related factors with vaccine series initiation using multivariable regression to estimate adjusted risk ratios (aRR) and risk differences (aRD) with 95% confidence intervals (CI). RESULTS: Among 221,190 pregnant individuals, vaccine coverage increased to 71.2% by December 2021. Gaps in coverage across categories of age and sociodemographic characteristics decreased over time, but did not disappear. Lower vaccine series initiation was associated with lower age (<25 vs. 30-34 years: aRR 0.53, 95%CI 0.51-0.56), smoking (vs. non-smoking: 0.64, 0.61-0.67), no first trimester prenatal care visit (vs. visit: 0.80, 0.77-0.84), and residing in neighborhoods with the lowest income (vs. highest: 0.69, 0.67-0.71). Vaccine series initiation was marginally higher among individuals with pre-existing medical conditions (vs. no conditions: 1.07, 1.04-1.10). CONCLUSIONS: COVID-19 vaccine coverage among pregnant individuals remained lower than in the general population, and there was lower vaccine initiation by multiple characteristics.