Indirect effectiveness of COVID-19 vaccines in the pre-omicron and omicron periods: A nation-wide test-negative case-control study in Brazil.

OBJECTIVES: Mass COVID-19 immunization campaigns altered the pandemic's progress by protecting the vaccine recipient and reducing transmission. However, evidence for indirect vaccine effectiveness (IVE) is limited due to the difficulties of ascertaining this type of protection. METHODS: Using linked national Brazilian databases, we adapted the test-negative design to evaluate the IVE against symptomatic infection. We analyzed data from January 1 to December 1, 2021 (pre-omicron) and January 1 to April 30, 2022 (omicron BA.1 and BA.2). We compared the probability of testing positive across various levels of second ancestral-strain monovalent COVID-19 vaccine dose coverage, including only unvaccinated individuals in the main analysis and both vaccinated and unvaccinated individuals in additional analyses. Sensitivity analysis focused on children younger than 12 years who did not have access to COVID-19 vaccines during the pre-omicron period. RESULTS: We included 11,039,315 unvaccinated individuals tested during the pre-omicron study period. IVE was minimal until 30% vaccination coverage (<10%), then it followed a dose-dependent pattern, peaking at 37.7 (95% confidence interval 32-42.8) at 70% coverage. For children younger than 12 years, IVE peaked at 59.8% (95% confidence interval 52.7-65.9) at 70% coverage. During the omicron period, IVE remained constant at about 5% across all comparisons. CONCLUSIONS: Our findings confirm that high vaccination coverage using vaccines that prevent infection indirectly protects the community. However, IVE was substantially higher during the pre-omicron period.

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.

Nanotechnology for COVID-19: Therapeutics and Vaccine Research.

The current global health threat by the novel coronavirus disease 2019 (COVID-19) requires an urgent deployment of advanced therapeutic options available. The role of nanotechnology is highly relevant to counter this "virus" nano enemy. Nano intervention is discussed in terms of designing effective nanocarriers to counter the conventional limitations of antiviral and biological therapeutics. This strategy directs the safe and effective delivery of available therapeutic options using engineered nanocarriers, blocking the initial interactions of viral spike glycoprotein with host cell surface receptors, and disruption of virion construction. Controlling and eliminating the spread and reoccurrence of this pandemic demands a safe and effective vaccine strategy. Nanocarriers have potential to design risk-free and effective immunization strategies for severe acute respiratory syndrome coronavirus 2 vaccine candidates such as protein constructs and nucleic acids. We discuss recent as well as ongoing nanotechnology-based therapeutic and prophylactic strategies to fight against this pandemic, outlining the key areas for nanoscientists to step in.

The Delay in the Licensing of Protozoal Vaccines: A Comparative History.

Although viruses and bacteria have been known as agents of diseases since 1546, 250 years went by until the first vaccines against these pathogens were developed (1796 and 1800s). In contrast, Malaria, which is a protozoan-neglected disease, has been known since the 5th century BCE and, despite 2,500 years having passed since then, no human vaccine has yet been licensed for Malaria. Additionally, no modern human vaccine is currently licensed against Visceral or Cutaneous leishmaniasis. Vaccination against Malaria evolved from the inoculation of irradiated sporozoites through the bite of Anopheles mosquitoes in 1930's, which failed to give protection, to the use of controlled human Malaria infection (CHMI) provoked by live sporozoites of Plasmodium falciparum and curtailed with specific chemotherapy since 1940's. Although the use of CHMI for vaccination was relatively efficacious, it has some ethical limitations and was substituted by the use of injected recombinant vaccines expressing the main antigens of the parasite cycle, starting in 1980. Pre-erythrocytic (PEV), Blood stage (BSV), transmission-blocking (TBV), antitoxic (AT), and pregnancy-associated Malaria vaccines are under development. Currently, the RTS,S-PEV vaccine, based on the circumsporozoite protein, is the only one that has arrived at the Phase III trial stage. The "R" stands for the central repeat region of Plasmodium (P.) falciparum circumsporozoite protein (CSP); the "T" for the T-cell epitopes of the CSP; and the "S" for hepatitis B surface antigen (HBsAg). In Africa, this latter vaccine achieved only 36.7% vaccine efficacy (VE) in 5-7 years old children and was associated with an increase in clinical cases in one assay. Therefore, in spite of 35 years of research, there is no currently licensed vaccine against Malaria. In contrast, more progress has been achieved regarding prevention of leishmaniasis by vaccine, which also started with the use of live vaccines. For ethical reasons, these were substituted by second-generation subunit or recombinant DNA and protein vaccines. Currently, there is one live vaccine for humans licensed in Uzbekistan, and four licensed veterinary vaccines against visceral leishmaniasis: Leishmune® (76-80% VE) and CaniLeish® (68.4% VE), which give protection against strong endpoints (severe disease and deaths under natural conditions), and, under less severe endpoints (parasitologically and PCR-positive cases), Leishtec® developed 71.4% VE in a low infective pressure area but only 35.7% VE and transient protection in a high infective pressure area, while Letifend® promoted 72% VE. A human recombinant vaccine based on the Nucleoside hydrolase NH36 of Leishmania (L.) donovani, the main antigen of the Leishmune® vaccine, and the sterol 24-c-methyltransferase (SMT) from L. (L.) infantum has reached the Phase I clinical trial phase but has not yet been licensed against the disease. This review describes the history of vaccine development and is focused on licensed formulations that have been used in preventive medicine. Special attention has been given to the delay in the development and licensing of human vaccines against Protozoan infections, which show high incidence worldwide and still remain severe threats to Public Health.

High cholera vaccination coverage following emergency campaign in Haiti: Results from a cluster survey in three rural Communes in the South Department, 2017.

Oral cholera vaccine (OCV) has increasingly been used as an outbreak control measure, but vaccine shortages limit its application. A two-dose OCV campaign targeting residents aged over 1 year was launched in three rural Communes of Southern Haiti during an outbreak following Hurricane Matthew in October 2016. Door-to-door and fixed-site strategies were employed and mobile teams delivered vaccines to hard-to-reach communities. This was the first campaign to use the recently pre-qualified OCV, Euvichol. The study objective was to estimate post-campaign vaccination coverage in order to evaluate the campaign and guide future outbreak control strategies. We conducted a cluster survey with sampling based on random GPS points. We identified clusters of five households and included all members eligible for vaccination. Local residents collected data through face-to-face interviews. Coverage was estimated, accounting for the clustered sampling, and 95% confidence intervals calculated. 435 clusters, 2,100 households and 9,086 people were included (99% response rate). Across the three communes respectively, coverage by recall was: 80.7% (95% CI:76.8-84.1), 82.6% (78.1-86.4), and 82.3% (79.0-85.2) for two doses and 94.2% (90.8-96.4), 91.8% (87-94.9), and 93.8% (90.8-95.9) for at least one dose. Coverage varied by less than 9% across age groups and was similar among males and females. Participants obtained vaccines from door-to-door vaccinators (53%) and fixed sites (47%). Most participants heard about the campaign through community 'criers' (58%). Despite hard-to-reach communities, high coverage was achieved in all areas through combining different vaccine delivery strategies and extensive community mobilisation. Emergency OCV campaigns are a viable option for outbreak control and where possible multiple strategies should be used in combination. Euvichol will help alleviate the OCV shortage but effectiveness studies in outbreaks should be done.

[National action plan for the emergence of invasive meningococcal disease in Chile, 2012-2013]. / Plan de acción nacional frente a la emergencia de la cepa W-135 responsable de enfermedad meningocócica invasora en Chile, 2012-2013.

Invasive meningococcal disease is challenging for public health, mainly when it manifests with sudden changes in incidence, serogroups and hypervirulent clones that spread in the population, causing great alarm due to its sequelae and often fatal course, a situation that occurred in Chile, starting at week 26 of the year 2012. To face this scenario, an organization of multidisciplinary teams was required, called W-135 Action Plan in Chile, which included sanitary alerts, education, reinforcement of the epidemiological surveillance of suspicious cases, immediate diagnosis through state-of-the-art techniques, blocking of contacts, communication plans, and, from the 42nd week, ON the vaccination campaign was started for children aged from 9-months-old to less than 5 years of age. The vaccination strategy had a great impact on the decrease in incidence (1.3 to 0.1/100,000) and case fatality rate in the vaccinated population (23% to 0%), with a high safety profile, leading to its subsequent inclusion in the national immunization program. The ability to develop molecular, clinical and epidemiological studies allowed us to better understand the situation, supporting public health policy decisions for its control. The W-135 Action Plan implemented by the Ministry of Health in Chile, to manage the outbreak of meningococcal disease by Neisseria meningitidis serogroup W, demonstrated that the coordination of these efforts, through an organized Action Plan, allows the implementation of campaigns at the national level achieving high coverage of risk populations in short periods of time, generating a positive impact on the health of the population.

Modelling an optimum vaccination strategy against ZIKA virus for outbreak use.

We present a model to optimise a vaccination campaign aiming to prevent or to curb a Zika virus outbreak. We show that the optimum vaccination strategy to reduce the number of cases by a mass vaccination campaign should start when the Aedes mosquitoes' density reaches the threshold of 1.5 mosquitoes per humans, the moment the reproduction number crosses one. The maximum time it is advisable to wait for the introduction of a vaccination campaign is when the first ZIKV case is identified, although this would not be as effective to minimise the number of infections as when the mosquitoes' density crosses the critical threshold. This suboptimum strategy, however, would still curb the outbreak. In both cases, the catch up strategy should aim to vaccinate at least 25% of the target population during a concentrated effort of 1 month immediately after identifying the threshold. This is the time taken to accumulate the herd immunity threshold of 56.5%. These calculations were done based on theoretical assumptions that vaccine implementation would be feasible within a very short time frame.

Plan de acción nacional frente a la emergencia de la cepa W-135 responsable de enfermedad meningocócica invasora en Chile, 2012-2013 / National action plan for the emergence of invasive meningococcal disease in Chile, 2012-2013

Invasive meningococcal disease is challenging for public health, mainly when it manifests with sudden changes in incidence, serogroups and hypervirulent clones that spread in the population, causing great alarm due to its sequelae and often fatal course, a situation that occurred in Chile, starting at week 26 of the year 2012. To face this scenario, an organization of multidisciplinary teams was required, called W-135 Action Plan in Chile, which included sanitary alerts, education, reinforcement of the epidemiological surveillance of suspicious cases, immediate diagnosis through state-of-the-art techniques, blocking of contacts, communication plans, and, from the 42nd week, ON the vaccination campaign was started for children aged from 9-months-old to less than 5 years of age. The vaccination strategy had a great impact on the decrease in incidence (1.3 to 0.1/100,000) and case fatality rate in the vaccinated population (23% to 0%), with a high safety profile, leading to its subsequent inclusion in the national immunization program. The ability to develop molecular, clinical and epidemiological studies allowed us to better understand the situation, supporting public health policy decisions for its control. The W-135 Action Plan implemented by the Ministry of Health in Chile, to manage the outbreak of meningococcal disease by Neisseria meningitidis serogroup W, demonstrated that the coordination of these efforts, through an organized Action Plan, allows the implementation of campaigns at the national level achieving high coverage of risk populations in short periods of time, generating a positive impact on the health of the population.

Initial evaluation of universal immunization with a single dose against hepatitis A virus in Central Brazil

ABSTRACT Vaccination against the hepatitis A virus (HAV) administered in two doses has been used effectively in universal child immunization programs in several countries. A single-dose vaccination was adopted in some low-income countries in an attempt to reduce costs without losing effectiveness. In 2014, single-dose universal vaccination was introduced in Brazil for children aged two years. Since such strategy is still not universally accepted, its efficacy should be compared to the two-dose strategy. To assess the humoral response after the single-dose HAV vaccination schedule, a cross-sectional study was conducted in Primavera do Leste, in Mato Grosso state, Central Brazil, including 265 children vaccinated through the National Immunization Program. Blood was collected by using a digital puncture and further applied to filter paper cards. Anti-HAV was detected in 218 out of 265 dried blood spots (DBS). Blood venous samples were collected from 34 out of 47 children who were not anti-HAV positive in DBS samples. Eighteen of them tested positive for anti-HAV, giving a final score of 93.6% (236/252) of seropositivity. In conclusion, this study demonstrated a high rate of anti-HAV positivity in the short term after single-dose hepatitis A vaccination in the population investigated. Moreover, the DBS was shown to be a reliable tool for detecting anti-HAV antibodies.

Evaluating Vaccination Strategies for Zika Virus in the Americas.

Background: Mosquito-borne and sexually transmitted Zika virus has become widespread across Central and South America and the Caribbean. Many Zika vaccine candidates are under active development. Objective: To quantify the effect of Zika vaccine prioritization of females aged 9 to 49 years, followed by males aged 9 to 49 years, on incidence of prenatal Zika infections. Design: A compartmental model of Zika transmission between mosquitoes and humans was developed and calibrated to empirical estimates of country-specific mosquito density. Mosquitoes were stratified into susceptible, exposed, and infected groups; humans were stratified into susceptible, exposed, infected, recovered, and vaccinated groups. Age-specific fertility rates, Zika sexual transmission, and country-specific demographics were incorporated. Setting: 34 countries and territories in the Americas with documented Zika outbreaks. Target Population: Males and females aged 9 to 49 years. Intervention: Age- and sex-targeted immunization using a Zika vaccine with 75% efficacy. Measurements: Annual prenatal Zika infections. Results: For a base-case vaccine efficacy of 75% and vaccination coverage of 90%, immunizing females aged 9 to 49 years (the World Health Organization target population) would reduce the incidence of prenatal infections by at least 94%, depending on the country-specific Zika attack rate. In regions where an outbreak is not expected for at least 10 years, vaccination of women aged 15 to 29 years is more efficient than that of women aged 30 years or older. Limitation: Population-level modeling may not capture all local and neighborhood-level heterogeneity in mosquito abundance or Zika incidence. Conclusion: A Zika vaccine of moderate to high efficacy may virtually eliminate prenatal infections through a combination of direct protection and transmission reduction. Efficiency of age-specific targeting of Zika vaccination depends on the timing of future outbreaks. Primary Funding Source: National Institutes of Health.

Initial evaluation of universal immunization with a single dose against hepatitis A virus in Central Brazil.

Vaccination against the hepatitis A virus (HAV) administered in two doses has been used effectively in universal child immunization programs in several countries. A single-dose vaccination was adopted in some low-income countries in an attempt to reduce costs without losing effectiveness. In 2014, single-dose universal vaccination was introduced in Brazil for children aged two years. Since such strategy is still not universally accepted, its efficacy should be compared to the two-dose strategy. To assess the humoral response after the single-dose HAV vaccination schedule, a cross-sectional study was conducted in Primavera do Leste, in Mato Grosso state, Central Brazil, including 265 children vaccinated through the National Immunization Program. Blood was collected by using a digital puncture and further applied to filter paper cards. Anti-HAV was detected in 218 out of 265 dried blood spots (DBS). Blood venous samples were collected from 34 out of 47 children who were not anti-HAV positive in DBS samples. Eighteen of them tested positive for anti-HAV, giving a final score of 93.6% (236/252) of seropositivity. In conclusion, this study demonstrated a high rate of anti-HAV positivity in the short term after single-dose hepatitis A vaccination in the population investigated. Moreover, the DBS was shown to be a reliable tool for detecting anti-HAV antibodies.

Impact of community-delivered SMS alerts on dog-owner participation during a mass rabies vaccination campaign, Haiti 2017.

Haiti has historically vaccinated between 100,000 and 300,000 dogs annually against rabies, however national authorities have not been able to reach and maintain the 70% coverage required to eliminate the canine rabies virus variant. Haiti conducts massive dog vaccination campaigns on an annual basis and utilizes both central point and door-to-door methods. These methods require that dog owners are aware of the dates and locations of the campaign. To improve this awareness among dog owners, 600,000 text messages were sent to phones in two Haitian communes (Gonaives and Saint-Marc) to remind dog owners to attend the campaign. Text messages were delivered on the second day and at the mid-point of the campaign. A post-campaign household survey was conducted to assess dog owner's perception of the text messages and the impact on their participation in the vaccination campaign. Overall, 147 of 160 (91.9%) text-receiving dog owners indicated the text was helpful, and 162 of 187 (86.6%) responding dog owners said they would like to receive text reminders during future rabies vaccination campaigns. In areas hosting one-day central point campaigns, dog owners who received the text were 2.0 (95% CI 1.1, 3.6) times more likely to have participated in the campaign (73.1% attendance among those who received the text vs 36.4% among those who did not). In areas incorporating door-to-door vaccination over multiple days there was no significant difference in participation between dog owners who did and did not receive a text. Text message reminders were well-received and significantly improved campaign attendance, indicating that short message service (SMS) alerts may be a successful strategy in low resource areas with large free roaming dog populations.

Pneumococcal meningitis trends after pneumococcal conjugate vaccine introduction in Colombia: An interrupted time-series analysis.

Colombia introduced mass pneumococcal conjugate vaccination at the end of 2011. Using 2005-2015 surveillance data, we conducted a retrospective interrupted time-series analysis. A significant trend towards reduced monthly was observed in the post-vaccination period (2012-2015) compared with the expected rate, reaching in 2015 a reduction of 90.5% of pneumococcal meningitis. This trend was not observed for control diseases.

The evolution of Vaccination Week in the Americas / La evolución de la Semana de Vacunación en las Américas / Evolução da Semana de Vacinação nas Américas

ABSTRACT This report covers the background and evolution of Vaccination Week in the Americas (VWA), an initiative that started as a coordinated response to a 2002 measles outbreak in Colombia and Venezuela, and evolved into the model for other regions and World Immunization Week (WIW). VWA focuses on the work of national immunization programs, with special efforts to reach the unreached. This paper offers examples of how countries have leveraged VWA to implement a diverse array of vaccination activities, strengthening overall health services by integrating with other preventive health interventions, and bolstering "Pan-Americanism" and health diplomacy. The opportunities offered by this global initiative were clearly demonstrated in April 2016 when the successful global switch from the trivalent oral polio vaccine to the bivalent vaccine was synchronized with WIW. Going forward, VWA and WIW can help close the gaps in access to immunization and other health services, contributing to achieve universal health coverage.(AU)

RESUMEN Este informe incluye los antecedentes y la evolución de la Semana de Vacunación en las Américas, una iniciativa que comenzó como una respuesta coordinada a un brote de sarampión en Colombia y Venezuela en el 2002, y evolucionó hasta convertirse en modelo para otras regiones y para la Semana Mundial de la Inmunización. La Semana de Vacunación en las Américas se centra en el trabajo de los programas nacionales de inmunización, con esfuerzos especiales para llegar a las personas que todavía no estén cubiertas. En el presente trabajo se dan ejemplos de cómo los países han aprovechado la Semana de Vacunación para realizar diversas actividades relacionadas con la vacunación, fortalecer los servicios de salud en general mediante la integración con otras intervenciones preventivas y fomentar el "panamericanismo" y la diplomacia en torno a la salud. Las oportunidades que ofrece esta iniciativa mundial quedaron claramente evidenciadas en abril del 2016 con el éxito obtenido en la sustitución de la vacuna oral trivalente contra la poliomielitis por la vacuna bivalente, sincronizada con la Semana Mundial de la Inmunización. En el futuro, la Semana de Vacunación en las Américas y la Semana Mundial de Inmunización pueden ayudar a subsanar la brecha en el acceso a la inmunización y otros servicios de salud, y contribui(AU)

RESUMO Este artigo narra os antecedentes e a evolução da Semana de Vacinação nas Américas (SVA), uma iniciativa que nasceu da resposta coordenada ao surto de sarampo na Colômbia e na Venezuela em 2002 e evoluiu como um modelo para as outras regiões e para a Semana Mundial da Imunização. A SVA põe ênfase no trabalho dos programas nacionais de vacinação e, principalmente, nos esforços para se alcançar quem ainda está inalcançado. São ilustrados exemplos de como os países têm aproveitado a SVA para implementar várias atividades de vacinação, fortalecendo os serviços de saúde em geral ao integrá-la a outras intervenções preventivas e reforçando o pan-americanismo e a diplomacia da saúde. As oportunidades criadas por esta iniciativa global ficaram bem evidentes em abril de 2016 com a bem-sucedida transição em nível mundial da vacina oral contra poliomielite trivalente à bivalente, em sincronia com a Semana Mundial da Imunização. Prosseguindo adiante, a SVA e a Semana Mundial da Imunização podem contribuir para sanar as lacunas no acesso à imunização e a outros serviços de saúde e alcançar a cobertura universal de saúde.(AU)

[Measles: the disease, epidemiology, history and vaccination programs in Chile]. / Sarampión: la enfermedad, epidemiología, historia y los programas de vacunación en Chile.

Measles, one of most important inmuno-preventable diseases, remains as a worldwide concern issue with an important morbidity and mortality. Particularly in the America region declared free of measles in 2010 by WHO, they still appear imported cases that origin outbreaks of variable magnitude in susceptible subjects usually none vaccinated which is the current situation in Santiago, the capital city of Chile. In this review we present characteristics of the etiological agent, the disease, epidemiological aspects with national historical focus, impact of immunization programs and outbreaks in Chile, in order to contribute to knowledge and management of this always present public health problem.

Sarampión: la enfermedad, epidemiología, historia y los programas de vacunación en Chile / Measles: the disease, epidemiology, history and vaccination programs in Chile

Measles, one of most important inmuno-preventable diseases, remains as a worldwide concern issue with an important morbidity and mortality. Particularly in the America region declared free of measles in 2010 by WHO, they still appear imported cases that origin outbreaks of variable magnitude in susceptible subjects usually none vaccinated which is the current situation in Santiago, the capital city of Chile. In this review we present characteristics of the etiological agent, the disease, epidemiological aspects with national historical focus, impact of immunization programs and outbreaks in Chile, in order to contribute to knowledge and management of this always present public health problem.

Sarampión una de las más importantes enfermedades inmuno-prevenibles, se mantiene como foco de preocupación en el mundo, con elevada carga de morbilidad y mortalidad. Particularmente en América, región declarada libre de esta enfermedad en 2010 por la OMS, se siguen identificando casos importados que originan brotes de diferente magnitud en personas susceptibles, habitualmente no vacunados, situación recientemente diagnosticada en Santiago, ciudad capital de Chile. En esta revisión, se presenta características del agente etiológico, de la enfermedad, aspectos epidemiológicos con foco en datos históricos nacionales, el impacto de los programas de vacunación, la ocurrencia de brotes en Chile, para contribuir al conocimiento y enfrentamiento de este siempre presente problema de salud pública.

Fatores associados à vacinação contra influenza entre trabalhadores de saúde de um complexo hospitalar de Salvador / Factors associated with influenza vaccination among health care workers in a hospital complex in Salvador

INTRODUÇÃO: Embora a vacina influenza seja anualmente recomendada para todos trabalhadores de saúde, estudos revelam que a cobertura vacinal desse grupo frequentemente é baixa. Diferentes fatores podem influenciar a vacinação contra a influenza, sendo necessário utilizá-los a favor da ampliação da cobertura vacinal.OBJETIVO: Identificar fatores que influenciam a prática de vacinar-se contra influenza entre trabalhadores de saúde. MATERIAIS E MÉTODOS: estudo transversal, ocorrido num Complexo Hospitalar de Salvador, Bahia. Utilizou-se um questionário autoaplicável, e os modelos "Conhecimento, Atitudes e Práticas" (CAP) e "Health Belief Model" (HBM). A vacinação contra influenza em 2014 (autorreferida)representou a variável principal, e fatores sociodemográficos,histórico de outras vacinas,conhecimentos e atitudes constituíram variáveis independentes.Considerou-se haver "conhecimento adequado", quando 75,0% ou mais dos indivíduos julgaram determinada informação corretamente. As análises foram feitas por regressão logística no Stata, versão 13, utilizando-se o teste qui-quadrado ao nível de 5% de significância, odds ratio, e intervalos de confiança de 95%. O modelo multivariado foi ajustado por sexo, idade e profissão, sendo composto pelas variáveis com p valor igual ou inferior a 0,20 na análise bivariada. A verificação de modelos alternativos mais adequados foi feita por retirada retrógrada, utilizando-se como parâmetro o "Critério de Informação de Akaike" (AIC). RESULTADOS: A amostra foi de 755 indivíduos, destacando-se técnicos de enfermagem (41,4%),enfermeiros (15,2%) e médicos (14,7%).Predominaram trabalhadores do sexo feminino (82,5%), entre 19 e 39 anos (82,4%), com 5 anos ou menos de experiência (67,5%). A cobertura vacinal global foi de 61,5%, sendo a maior entre enfermeiros (69,0%) e a menor entre médicos (49,1%). Os principais motivadores da vacinação foram conhecer a recomendação da vacina para si (49,0%), confiar em vacinas no geral (41,6%) e na eficácia da vacina influenza (35,4%). Os principais desmotivadores foram esquecimento (37,3%), inconveniência de locais/horários (22,5%) e não saber da campanha (16,3%). A principal estratégia que facilitaria a vacinação foi vacinar os trabalhadores no seu próprio setor de trabalho (56,6%). O conhecimento foi adequado no julgamento de 9/16 das informações, com destaque para médicos (15/16) e enfermeiros (13/16). A maior adequação (94,6% de acerto)refere-se à indicação da vacina para todo trabalhador de saúde, e o conhecimento menos adequado foi sobre a incapacidade da vacina causar a influenza (32,0% de acerto). Os fatores associados à vacinação foram: conhecer que pessoas saudáveis também precisam se vacinar contra influenza (OR=3,15 ; IC95%: 1,74 - 5,71); saber que a vacina não protege por muitos anos (OR=2,08 ; IC95%: 1,30 - 3,33); e não ter medo dos efeitos adversos pós-vacinais (OR=1,93 ; IC95%: 1,26 - 2,95). CONCLUSÕES: a vacinação contra influenza é influenciada por onhecimentos,atitudes e questões organizacionais/operacionais.Medidas educativas e de desmistificação de questões relacionadas à influenza e à vacina, bem como ampliação de dias/horários e locais de vacinação de acordo com a conveniência dos trabalhadores de saúde, devem compor as estratégias voltadas à elevação da cobertura da vacina influenza neste grupo.

INTRODUCTION: Although the influenza vaccine is recommended annually for all health workers, studies show that vaccination coverage of this group is often low. Different factors can influence the vaccination against influenza, it is necessary to use them in favor of the expansion of vaccination coverage. GOAL: To identify factors that influence the practice of vaccination against influenza among health workers. MATERIALS AND METHODS: A cross-sectional study, which took place in a hospital complex in Salvador, Bahia. We used a self-administered questionnaire, and the models "Knowledge, Attitudes and Practices"(CAP) and "Health Belief Model"(HBM). Influenza vaccination in 2014 (self-reported) was the main variable, and sociodemographic factors, history of other vaccines, knowledge and attitudes were independent variables. Considered to be "appropriate knowledge" as 75.0% or more of subjects judged certain information correctly. Analyses were performed by logistic regression using Stata, version 13, using the chi-squared test at 5% significance, odds ratio, and 95% confidence intervals. The multivariate model was adjusted for sex, age and profession, being composed of the variables that had a pvalue less than or equal to 0.20 in the bivariate analysis. The verification of most suitable alternative models was performed by backward withdrawal, using as a parameter the "Akaike Information Criteria" (AIC). RESULTS: The sample consisted of 755 individuals, mainly nursing technicians (41.4%), nurses (15.2%) and physicians (14.7%). There was a predominance of female workers (82.5%), between 19 and 39 years (82.4%), with five years or less experience (67.5%). The global vaccination coverage was 61.5%, the highest among nurses (69.0%) and lowest among physicians (49.1%). The main motivators to get vaccinated were to know the recommendation of the vaccine for themselves (49.0%), trust in vaccines in general (41.6%) and in the effectiveness of influenza vaccine (35.4%). The main demotivating were forgetfulness (37.3%), inconvenience locations/times (22.5%) and not knowing the campaign (16.3%). The main strategy would facilitate the vaccination was to inoculate workers in their own work sector (56.6%)...