Respiratory diseases are the second leading cause of hospital admissions and the third leading cause of death worldwide, affecting 10% to 20% of the world’s population. ¹ Among them, influenza is present with its complications and evolution to severe forms, being considered, in the ranking, the first in number of hospital admissions, causing deaths and high costs to health services. ² And subtype A is responsible for the occurrence of most epidemics worldwide. ³

Influenza is an acute viral infectious disease of the respiratory system, which is highly transmissible and globally distributed, and has a self-limiting course. However, when severe forms manifest, it causes rapid and fatal death, especially in individuals who present risk factors or conditions for complications from the infection. ³ The influenza virus, called Myxovirus influenzae, branches into types A, B and C, and only types A and B show clinical relevance in humans, being correlated with outbreaks and epidemics of respiratory origin. ⁴

The most common complications of the influenza virus are influenza-like syndrome (IS), which consists of cases of people with fever, accompanied by cough and/or sore throat, with symptoms beginning in the last seven days, and severe acute respiratory syndrome (SARS), which is characterized by cases of people of any age, with IS, who present dyspnea or oxygen saturation (SpO₂) < 95%, in room air, signs of respiratory distress and increased respiratory rate, according to age, and hypotension, in relation to frequent blood pressure, before the onset of symptoms. ³

Surveillance of influenza and other respiratory viruses in Brazil consists of sentinel surveillance of IS and surveillance of SARS in hospitalized patients and deaths from SARS. Its objective is to monitor cases of IS due to respiratory viruses of public health importance in selected health units, called sentinel units, so that they serve as an early warning to the surveillance system. ⁵

Worldwide, it is estimated that one billion cases of influenza occur annually, with three to five million cases of severe illness, with mortality ranging from 290,000 to 650,000 due to complications related to the disease. ⁶ In Brazil, in 2024, up to epidemiological week (EW) number 37, 61,124 cases of SARS were reported, with identification of respiratory viruses, 27% of which were influenza viruses, with 22% of deaths. ⁷ In Ceará, up to EW 15 of 2024, it is shown that the influenza A virus was detected in 1,631 (46.8%) samples. Of these, 275 (16.9%) were subtyped, with a predominance of H1N1 in 172 (62.5%). A total of 2,268 cases of SARS were also confirmed in the state. ⁸

At a national level, care for patients with influenza must currently be provided in accordance with the Influenza Management and Treatment Guide, which aims to guide therapeutic conduct for influenza, as well as intra- and extra-hospital control measures. ⁵

Knowing and assessing nurses’ knowledge profile on the clinical management of patients with influenza will involve local, state and federal municipal managers, together with health professionals from each region of the country, to create ongoing and permanent educational strategies, through training on the use of influenza management and treatment guides, seeking to minimize errors resulting from unsafe care, as well as complications and injuries resulting from the disease. Thus, the study aims to assess nurses’ knowledge profile regarding the indications for the clinical management of influenza.

This is a descriptive cross-sectional study carried out in Basic Health Units (BHU), Emergency Care Unit, polyclinic and municipal hospital, located in the municipality of Quixadá, in the state of Ceará, with approximately 80,600 inhabitants. The report was guided by the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) statement. ⁹

The study population consisted of 70 nurses, with the sample consisting of nurses working in the city’s health services. Nurses who had been working for more than three months in these locations were included. Nurses who were on maternity leave, vacation or away from work for some other reason during the data collection period were excluded, totaling 53 nurses.

The data were collected in October 2019, using a questionnaire-type instrument, prepared based on the Ministry of Health’s 2017 Influenza Treatment Protocol. ¹⁰ The questionnaire has 11 items.

To collect data, daily visits were made to services, from Monday to Friday, approaching nurses, before or after their care activities, without interfering in care routine. At this time, the purpose of the study and its objective were presented to participants, explaining the importance of the Informed Consent Form. After a participant signed, the questionnaire was given to the participant to complete.

The data were tabulated in a spreadsheet created in Microsoft Excel by the researcher himself, based on the variables in the questionnaire. They were then subjected to statistical analysis using EPI INFO 7.0, generating percentage frequencies, which were displayed in tables and later interpreted and discussed in conjunction with the bibliography on the subject.

The research was designed in compliance with the ethical aspects recommended in Resolutions 466/12 and 518/2018 of the Brazilian National Health Council, which regulate research with human beings, and was approved under Opinion 3,660,758 and Certificate of Presentation for Ethical Consideration 23697019.7.0000.5046, on 10/24/2019.

The sociodemographic characterization of the 53 nurses participating in the research showed that the majority were women (49; 92.4%), aged between 31 and 59 years old (47; 88.8%), married/stable union (32; 60.0%), working at the BHU (18; 34.0%) (Table 1).

Table 1 Table 1 Sociodemographic characterization of nurses in health services of Quixadá, Ceará. Quixadá, Ceará, Brazil, 2019

Variables	n=53(%)
Sex Male Female	04 (7.6%) 49(92.4%)
Age group18-30 years 31-59 years >=60 years	05(9.4%) 47(88.8%) 01(1.8%)
Marital status Single Married/stable union	21(40.0%) 32(60.0%)
Health serviceBasic Health UnitEmergency Care UnitPolyclinicMunicipal hospital	18(34.0%) 16(30.0%) 03(6.0%) 16(30.0%)

Source: research data (2019).

The analysis of the distribution of indications for the clinical management of patients with IS who present risk factors for complications revealed that all nurses demonstrated knowledge about the importance of the use of symptomatic medications, adequate hydration and oseltamivir phosphate, with 100% agreement on each of these measures (53; 100.0%). Furthermore, 81% of nurses (43) indicated the need to return to the health service to review patients’ clinical condition, while 19% (10) did not mention this recommendation (Table 2).

Table 2 Table 2 Distribution of indications for clinical management of patients with influenza-like illness, with risk factors for complications, according to nurses’ knowledge. Quixadá, Ceará, Brazil, 2019

Variables	n=53(%)
Symptomatic medications Yes	53(100.0%)
Hydration Yes No Does not know	53(100.0%)
Oseltamivir phosphate Yes	53(100.0%)
Returning to the health service to review the clinical condition Yes No	43(81.0%) 10(19.0%)

Source: research data (2019).

The distribution of conditions and risk factors for complications, according to nurses’ knowledge, indicated unanimous agreement (53;100%) in several categories, including pregnant women at any gestational age, postpartum women up to two weeks postpartum, adults aged 60 or over, children under five years old and individuals with conditions such as lung diseases, tuberculosis, cardiovascular diseases, nephropathies, liver diseases, hematological diseases, metabolic disorders, neurological disorders, immunosuppression, neoplasms, HIV/AIDS, among others, in addition to obesity.

A significant number of nurses (50;94%) also recognized the indigenous population living in villages or with difficult access as a risk group. However, a relevant portion (36;68%) is unaware that individuals under 19 years of age who are taking acetylsalicylic acid (ASA) for a long time are at risk of complications, which highlights an important gap in knowledge (Table 3).

Table 3 Table 3 Distribution of condition(s) and risk factor(s) for influenza complications according to nurses’ knowledge. Quixadá, Ceará, Brazil, 2019

Variables	n=53(%)
Pregnant women at any gestational age Yes	53(100.0%)
Women who have given birth up to two weeks after giving birth Yes	53(100.0%)
Adults ≥ 60 years Yes	53(100.0%)
Children < 5 years Yes	53(100.0%)
Indigenous population living in villages or with difficult access Yes Does not know	50(94.0%) 03(6.0%)
Individuals under 19 years of age using acetylsalicylic acid for a long time Yes No Does not know	11(21.0%) 36(68.0%) 06(11.0%)
Individuals with lung disease, tuberculosis of all forms, cardiovascular disease, nephropathy, liver disease, hematological diseases, metabolic disorders, neurological and developmental disorders that may compromise respiratory function or increase the risk of aspiration, immunosuppression associated with medications, neoplasms, HIV/AIDS or others, obesity Yes	53(100.0%)

Source: research data (2019).

In relation to the distribution of indications for clinical management of patients with IS, without risk factors for complications, the results were heterogeneous. All nurses reported the indication of hydration (53; 100.0%), while 48 (91.0%) mentioned the use of symptomatic medications, 36 (68.0%), the use of oseltamivir phosphate, and 41 (77.0%) advised returning to the health service to review the clinical condition (Table 4).

Table 4 Table 4 Distribution of indications for clinical management of patients with influenza-like illness, without risk factors for complications, according to nurses’ knowledge. Quixadá, Ceará, Brazil, 2019

Variables	n=53(%)
Symptomatic medications Yes No	48(91.0%) 05(9.0%)
Hydration Yes	53(100.0%)
Oseltamivir phosphate Yes No Does not know	36(68.0%)16(30.0%)01(2.0%)
Returning to the health service to review the clinical condition Yes No	41(77.0%) 12(23.0%)

Source: research data (2019).

The distribution of indications for the clinical management of pregnant and postpartum women, according to nurses’ knowledge, identified that all refer to: complete physical examination with measurement of vital signs (53; 100.0%); observing warning signs in pregnant women with respiratory rate values >20 rpm or heart rate >100 bpm% (53; 100.0%); and precautions with newborns in the postpartum period (53; 100.0%) (Table 5).

Table 5 Table 5 Distribution of indications for clinical management of pregnant and postpartum women according to nurses’ knowledge. Quixadá, Ceará, Brazil, 2019

Variables	n=53(%)
Complete physical examination with measurement of vital signs Yes	53(100%)
Observing warning signs in pregnant women with respiratory rate values >20 rpm or heart rate >100 bpm% Yes	53(100%)
Oxygen therapy, continuous monitoring and hospital admission if there are signs of worsening, including SatO2<95% Yes No	50(94.0%) 03(6.0%)
Oseltamivir phosphate Yes No Does not know	49(92.0%) 01(2.0%) 03(6.0%)
Radiological examination Yes No	52(98.0%) 01(2.0%)
Controlling hyperthermia with paracetamol Yes No Does not know	47(89.0%) 04(7.0%) 02(4.0%)
Precautions for newborns in the postpartum period Yes	53(100.0%)

Source: research data (2019).

All nurses are aware of the indications for clinical management of patients with SARS, such as: hospital admission; intravenous hydration; oxygen therapy; maintaining clinical monitoring; measuring vital signs; oseltamivir phosphate; collecting respiratory secretion samples for laboratory testing; and indications for hospitalization of patients with influenza in the Intensive Care Unit (ICU), such as: persistent hemodynamic instability; signs and symptoms of respiratory failure, including hypoxemia requiring oxygen supplementation to maintain arterial oxygen saturation above 90%; and progression to other organ dysfunctions, such as acute renal failure and neurological dysfunction.

As for the problems and failures in implementing clinical management based on the 2017 Influenza Treatment Protocol, all reported a lack of training on the use of the protocol (53; 100.0%), and more than 50% reported a lack of knowledge about the disease (34; 64.0%), lack of knowledge about the protocol (37; 70.0%) and lack of training by the municipality (45; 85.0%).

The study describes the knowledge of 53 nurses about the indications for the clinical management of patients with influenza, a seasonal infection that causes significant morbidity and mortality and economic losses, worldwide and every year, requiring targeted and quality care for patients at different levels of care. ¹¹

Regarding the disease clinical management, it is known that all patients with IS and with conditions and risk factors for complications should be advised to return to the health service for a review of clinical condition, where they should be reassessed in relation to the criteria for SARS or other signs of worsening. It can be seen, therefore, that the professionals investigated had good knowledge regarding many care measures; in this item, however, the health team needs to know that the importance of returning to the health service to reassess the health status is an essential step in the clinical management of the disease of patients with IS and risk factors for complications. ⁵

The study showed that, in the sample analyzed, there are nurses who are unaware that indigenous populations living in villages or with difficult access constitute one of the risk factors for complications from influenza. However, Ordinance 2,436 of September 21, 2017, which approves the Brazilian National Primary Care Policy, considers that it is a common responsibility of all members of teams working in Primary Health Care, such as nurses, to be responsible for monitoring the population involved, meeting the needs for preventive care and seeking comprehensiveness in the provision of services. ^12-13

Another variable that deserves attention, as it presented a result that differs from what is recommended in the literature, is that individuals under 19 years of age, in prolonged use of ASA, is also not a risk factor for complications from influenza. In this context, it is worth mentioning that, since 1980, the Food and Drug Administration and the Centers for Disease Control and Prevention recommend that aspirin should not be used to treat acute febrile viral illnesses in children and adolescents under 19 years of age, as its use may cause Reye’s syndrome, which is a rare but life-threatening acute non-inflammatory encephalopathy with fatty liver failure. ^14-15

Regarding the indications for clinical management of patients with IS without risk factors for complications, a significant percentage of nurses report that the use of oseltamivir phosphate is not recommended. It is known that oseltamivir phosphate has extensive evidence supporting its safe and effective use in the treatment and prevention of influenza in older adults, including those with complicated infections or who reside in Nursing Homes, requiring only dose adjustments in renal patients. ¹⁶ Furthermore, its prescription, in addition to symptomatic medications and hydration, should be considered based on clinical judgment, preferably in the first 48 hours after the onset of the disease. ⁵

During pregnancy, extending into the puerperal phase, physiological changes occur, including changes in cellular immunity, increased heart rate and systolic volume, and increased oxygen consumption, which leads to cautious care by nurses when pregnant and postpartum women are affected by influenza. It is a cause for concern that, in this study, some nurses reported not knowing important indications when approaching this population. ^17-18 However, ideally, these professionals, in their services, should promote efforts to improve vaccination coverage, through informative conversations with patients, which could protect mothers and their babies against serious respiratory diseases. ¹⁹

Regarding the care of patients with influenza that progress to SARS, characterized by symptoms of high fever, cough and dyspnea, accompanied by increased respiratory rate, hypotension in relation to patients’ usual blood pressure, and, often, lack of smell, taste and appetite, it is known that the recognition of these signs of severity by nurses is essential, in order to carry out the appropriate indications in the clinical management of these patients, as seen in the results of this research, as this is one of the most worrying manifestations among respiratory infections in humans. ^{5, 20}

Turning to indications for patients with influenza who should be admitted to the ICU, research, which sought to analyze a large cohort of patients hospitalized, in this context, for severe influenza, over ten years, showed that overall mortality was 25.1%. The predominant clinical presentation was specific lung involvement, which rapidly required mechanical ventilation and often progressed to acute respiratory distress syndrome. Therefore, timely admission to the ICU is recommended as early as possible in cases of respiratory failure in order to allow effective intensive care, which was known to all nurses working in the health services studied. ²¹

Finally, regarding the problems and failures in implementing clinical management based on the 2017 Influenza Treatment Protocol, alarming data were found in the research regarding nurses’ lack of knowledge about influenza and the protocol for managing it clinically, as well as the result of a study that sought to understand the dynamics of knowledge, attitudes and practices of health professionals related to influenza, suggesting political implications and advocating the review of national strategies to strengthen the training of health professionals on a disease that has been present in Brazil since the last century, and which has a large increase in the number of cases each year. ²²

Furthermore, the report of the municipality’s lack of training on the disease and the use of the treatment protocol is quite concerning, considering that influenza continues to cause up to five million cases of serious illness resulting in 500,000 deaths worldwide. ²³ However, in Brazil, the Brazilian National Policy for Continuing Education seeks to transform health work, with the aim of encouraging critical, reflective, committed and technically efficient action, and respect for regional characteristics and specific training needs of professionals working in health services, for the transformation of health practices towards meeting the fundamental principles of the Brazilian Health System, based on local reality and collective analysis of work processes. It is clear that it is the role of health managers and professionals to seek to improve health practices to the detriment of offering quality care. ²⁴

Finally, each year, changes in the viral involvement profile of different types of diseases may reflect the effect of different variants, which implies the relevance of knowledge by nurses as well as by all health professionals about the clinical management not only of influenza, but of several other viral infections, based on the recommendations of official guidelines and protocols of national and international government agencies, in order to offer safe care to patients. ²⁵

The study’s limitations included the lack of availability and lack of interest of most professionals in answering the questionnaire, as many reported not feeling confident enough to answer, mainly due to a lack of knowledge about the protocol and even about the disease. Many nurses also stated that there were no cases of influenza in their services.

In conclusion, the study achieved its objective by assessing nurses’ knowledge profile regarding the indications for clinical management of influenza. The results demonstrate that, although nurses have a good level of knowledge in most of the areas assessed, some important gaps were identified.

It is suggested that municipal health departments carry out more frequent training in relation to the entire context surrounding the disease, since it is a pathology that affects people worldwide every year.