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Influenza Lesson

November 21, 2014


Fascinating Flu Fact #1: Every year, a new flu vaccine is developed to fight the specific strains of flu virus that are expected to circulate. 
Fascinating Flu Fact #2: The 2016 flu season, over 90 percent of the circulating flu viruses tested by the CDC match “Flu A” strains. That’s a lot of Flu A.
Fascinating Flu Fact #3: In California, flu season typically starts peaking right after the first of the year. In other words, it’s actually not too late to get a flu vaccine in January…and the California Department of Public Health says this influenza season is shaping up to be a lengthy one.

Fascinating Flu Fact #4: CDC recommends the flu vaccine for everyone 6 months and older to help prevent influenza illness

Fascinating Flu Fact # 5: Hand hygiene can reduce the spread of influenza



Influenza is a respiratory infection caused by influenza virus. Commonly known as the “flu”, influenza is an acute febrile respiratory illness that occurs in annual outbreaks of varying severity and commonly in unpredictable worldwide epidemics (pandemics), caused by infection with influenza type A or B virus. Influenza viruses are constantly changing, with new strains appearing regularly. Seasonal influenza can include the H1N1 virus commonly known as the “swine flu”. Severe acute respiratory syndrome (SARS) is a similar respiratory illness caused by a coronavirus called SARS-associated coronavirus (SARS-CoV).  Middle East respiratory syndrome (MERS-CoV) virus, is a new variant coronavirus which is a different virus from the SARS agent, that was recognized in two patients in September 2012 who exhibited acute respiratory distress syndrome. It has affected patients with connections to several Middle Eastern countries. The causative virus infects the respiratory tract, is highly contagious, and typically produces prominent systemic symptoms early in the illness.

Influenza virus infection can produce various clinical syndromes in adults, including nonfebrile common colds, pharyngitis, tracheobronchitis, and pneumonia. Other respiratory viruses, such as respiratory syncytial virus  (RSV) or adenovirus may also produce influenza-like illness. Influenza may initially seem like a common cold with a runny nose, sneezing and sore throat. But unlike the common colds which usually develop slowly, influenza comes on suddenly and the symptoms are much worse than the  common cold.

The predominant respiratory viruses that can cause severe pneumonia include various influenza viruses and respiratory syncytial virus (RSV). Both influenza virus and RSV can be detected in respiratory secretions. Respiratory syncytial virus (RSV) is a highly contagious seasonal virus that is the single most common cause of lower respiratory tract infections in infants and children. Approximately 80 percent of infants are infected with RSV within their first year of life. Peak incidence occurs between 2 and 6 months, with nearly all children infected by age two years. RSV infections occur throughout the year but usually reach epidemic levels during its peak season (winter months). Most infections present like a common cold, are self-limiting and treated at home. In the United States, approximately 80,000 to 125,000 infants are hospitalized with RSV per year with 20 to 25 percent of those admitted developing pneumonia. It is also estimated that RSV is associated with more than 11,000 deaths each year in the United States, with most deaths occurring in elderly people and in patients with chronic cardiopulmonary disease. RSV immunity is rarely obtained. Viral shedding may last for four or more weeks. Although reinfections are common, subsequent infections tend to be less severe.

RSV is more common and generally more severe in males. Recurrent infection with RSV can occur throughout life. Bronchiolitis resulting from RSV occurring in the first year of life is a risk factor for the development of asthma later in life. Bronchiolitis is a viral-induced inflammation of the bronchiolar epithelium that causes hypersecretion of mucus and edema of the submucosa. These factors result in mucus plugging and obstruction of the bronchioles, leading to a narrowing of the airway and hyperinflation or collapse of the distal lung tissue. Infants are most vulnerable due to their smaller airway size.

Influenza A viruses have caused five pandemics of varying severity within the past 120 years. The pandemic in 1918 to 1919 caused at least 500,000 deaths in the United States and more than 40 million worldwide, whereas the 2009 H1N1 pandemic was associated with substantially less mortality. Seasonal epidemics may cause enormous morbidity, economic loss, and often substantial mortality. It is estimated that influenza infections are responsible for in excess of 36,000 respiratory- and circulatory-related deaths annually in the United States, predominantly in elderly patients and those with underlying cardiopulmonary or metabolic disease. Influenza-associated pneumonia is also common in high-risk patients with underlying disease and in residents of nursing homes or other chronic care facilities during the flu season of October through May, especially in patients who have not received appropriate vaccination.


The Pathogen

Influenza viruses belong to the family Orthomyxoviridae and are divided into three types (A, B, and C) distinguished by their internal and external proteins. Influenza C viruses have seven segments and only a single surface glycoprotein. Whereas influenza B and C viruses are principally human pathogens, influenza A viruses primarily infect aquatic birds and sometimes other animal hosts, including other avians, swine, horses, marine mammals, felids, and dogs. Influenza A viruses are further classified into subtypes. Each strain is identified by type, subtype if influenza A, site, sample number, and year of isolation.

Influenza virus infection is transmitted from person to person by virus-containing respiratory secretions. The virus is transmitted by small-particle aerosols and deposited on the respiratory tract epithelium. Once the virus initiates infection of the respiratory tract epithelium, successive cycles of viral replication infect large numbers of cells and result in destruction of respiratory epithelium and sometimes pneumocytes through direct cytopathic effects or apoptosis.

H1H1 is transmitted from person to person through droplets present in the air from a sick person’s cough or sneeze. It can also be transmitted by touching something with the virus living on it, such as a doorknob, and then touching your eyes, nose, or mouth.  The virus can live on surfaces for 2 to 8 hours.

RSV is caused by a single strand RNA virus. There are two subtypes: strain A and B; strain A is more virulent. RSV is transmitted via direct contact with infected secretions by fomite, hand-to-hand contact and large particle respiratory aerosols. The most common inoculation sites include the eyes, nose and mouth. RSV organisms are shed by an infected person for 1 to 2 days before and up to 2 to 4 weeks after onset of symptoms. The RSV Virus survives on environmental surfaces for up to 30 hours and for one hour on hands and incubation period is 2 to 5 days. RSV replicates in the nasopharynx and confines itself to the respiratory mucosa. It does not spread systemically. In the “at-risk” patient, the infection will progress downward (over 1 to 3 days) in the respiratory tract and develop into an acute lower respiratory tract infection.


Clinical Manifestations of Influenza Syndrome

Influenza is characterized by an abrupt onset of fever, chills, rigors, headache, myalgia, and malaise but these classic symptoms occur in less than two thirds of cases. Initially, systemic symptoms are predominant. Myalgia, arthralgias, malaise, and headache are usually the most troublesome early symptoms, and their severity is related to the level of fever. Ocular symptoms, including photophobia, tearing, burning, and pain on moving the eyes, are sometimes present. Conjunctivitis is characteristic in avian H7 virus infections. Respiratory symptoms, particularly dry cough and nasal discharge, are typical early in the illness but are overshadowed by the systemic symptoms. Other common symptoms include nasal obstruction, hoarseness, and sore throat. As systemic illness diminishes, respiratory complaints and findings become more apparent. Cough is the most frequent and troublesome symptom and may be accompanied by substernal discomfort or burning. Cough,  lassitude, and malaise may persist for several weeks before full recovery.

Fever is the most important initial physical finding. The temperature usually rises rapidly to a peak of 38° to 40° C within 12 hours of onset, concurrently with systemic symptoms. Fever is usually continuous but may be intermittent, especially if antipyretics are administered. Typically, the duration of fever in adults is about 3 days, but it may persist from only 1 to 5 or more days. Early in the course of illness, the patient appears toxic, the face is flushed, and the skin is hot and moist. The eyes are watery and reddened. Clear nasal discharge is common. The mucosa of the nose and throat is hyperemic, but exudate is not observed. Small, tender cervical lymph nodes are often present. Transient scattered rhonchi or localized areas of rales are found in less than 20% of cases.


Signs and Symptoms

Signs and symptoms of uncomplicated influenza include flu-like symptoms like a running nose. Other symptoms may include fever, cough, sore throat, nasal congestion or rhinorrhea, headache, muscle pain, and malaise. Diarrhea and/or vomiting may be present especially in children, but without evidence of dehydration. Symptoms of complicated or severe influenza include lower respiratory tract disease symptoms like shortness of breath, dyspnea, tachypnea, and hypoxia. Other symptoms of severe influenza include central nervous system (CNS) abnormalities, severe dehydration, pneumonia, secondary complications including renal failure, multi-organ failure, septic shock, rhabdomyolysis, myocarditis and exacerbation of underlying chronic diseases.



Anyone can get influenza. But the following groups of people have a higher risk of developing influenza.

  • Pregnant women
  • People living with or caring for infants under 6 months of age
  • Health care workers
  • Emergency medical personnel
  • Children and young adults from the age of 6 months through 24 years
  • People ages 25 through 64 with chronic medical conditions like asthma, diabetes, or weakened immune systems.
  • People who live in facilities along with many other residents, such as nursing homes or military barracks or jails, are more likely to develop influenza



Although anyone can get influenza, the following are more likely to have complications from the virus

  • Infants and young children have higher rates of influenza-associated hospitalization than older children
  • Influenza illness may be more serious in children < 2 years old
  • Persons with chronic medical conditions (such as heart disease, cancer or diabetes), are at increased risk for complications from influenza
  • Women who are pregnant and women who are less than two weeks postpartum
  • Elderly people ≥ 65 years old are also at higher risk for influenza complications
  • Immunocompromised patients



For most healthy young adults, influenza is not a serious disease and it is self limiting with no lasting effects. But high-risk children and adults may develop complications such as pneumonia, bronchitis, asthma flare-ups, sinus infections, and ear infections. Pneumonia is the most serious complication of influenza and it can be deadly to people with a chronic illness. 



Most people don’t need medical care and will get better on their own with just rest and fluids as most flu viruses are self-limiting. Acetaminophen can be taken for fevers and body aches. Some home remedies like ginger or garlic tea will alleviate the symptoms. For those with severe illness or are more likely to have complications, antivirals such as Tamiflu may be prescribed. Antiviral treatment is recommended as early as possible for any patient with confirmed or suspected influenza who is hospitalized, has severe, complicated, or progressive illness, or who is at risk for complications. The benefit of antivirals is greatest when treatment is started early, especially within 48 hours of illness. Although antivirals lessen the symptoms, they do not make the virus go away or make the patients less contagious.



Nurse Assistants should teach the infected patient to cover their nose and mouth with a tissue or use their sleeve when they cough or sneeze. Patients should wash their hands often with soap and water and/or use gel sanitizers. They should avoid touching their eyes, nose or mouth to stop the spread of bacteria. For caregivers who are sick, they should stay at home and should not take care of patients.


Nurse Assistant strategies for taking care of a patient with Influenza

  • Monitor oxygen saturations when doing vital signs or as ordered and notify the primary Nurse if O2 sats <90%. The goal is to maintain adequate oxygenation at 90 percent or greater
  • Support respiratory effort by elevating head of bed to 30 degrees or higher for ease of breathing
  • Perform frequent position changes, decreased stimulation, and cluster care to conserve energy, increase oxygenation and promote rest.
  • Assist with clearance of nasal secretions as needed based on oxygen desaturations
  • Report any respiratory distress to the primary nurse.
  • Monitor oxygen levels with continuous pulse oximetry if ordered.
  • Promote adequate rest in a calm, quiet environment
  • Coordinate and cluster care to promote extended and uninterrupted rest periods


Infection Control Precautions

Patients hospitalized with human influenza should be managed with standard and droplet precautions. Masks appear to be as effective as respirators in protecting health care workers during seasonal influenza. Patients hospitalized with presumed H5N1 or other novel strains warrant airborne, droplet, and contact precautions, including eye protection. Compliance with masks and hand hygiene also appears to reduce the risk of secondary infections in household contacts.

Since Healthcare-associated spread is very common; initiate isolation technique immediately on admission if RSV test results are pending or if RSV infection is suspected. You do not have to wait till the results of RSV are back before isolating the patient. As soon as RSV is suspected, place the patient on droplet isolation immediately and observe infection control guidelines to protect yourself and other patients.

  • Standard/Contact/Droplet isolation: staff/visitors should use gowns, gloves, masks and protective eye wear (e.g., eye/nose goggles, face shield) when within three to six feet of infected patient, when direct physical contact is necessary and with activities likely to create splashes/sprays of infected secretions. Use single room when possible, keeping door closed and patient confined to room.
  • Encourage patient to limit visitors; post isolation signs in appropriate languages.
  • Cohort patients, patient assignments and staff.
  • Practice good hand hygiene when entering/leaving room, before/after direct care/contact with patient, after contact with inanimate objects in direct vicinity of patient and after removing gloves.
  • Disinfect all items coming in contact with patient (e.g., medical equipment like Dinamap, pulse oximetry and Telemetry boxes)


If you have influenza, to avoid spreading the flu, follow the following best practices;

  • Wash your hands regularly, and keep your hands away from your face
  • Practice Respiratory Etiquette Cover your cough and sneeze
  • Use tissue to contain respiratory secretions and dispose of them immediately in the nearest waste receptacle
  • If you have signs and symptoms of influenza like illness (fever, cough, sore throat), please stay at home and do not go to work sick!
  • Stay home from work and other public places until you are feeling better and your fever has been gone for at least 24 hours. The fever needs to have gone away on its own without the help of medicine.
  • To prevent the flu in the future, get a flu vaccine every fall. Encourage people living with you to get the vaccine.



Annual influenza vaccination is recommended for all persons ≥ 6 months old who have no contraindications to the vaccine. Inactivated influenza vaccines for persons 6 months of age and older, a high-dose inactivated vaccine for persons 65 years of age and older, and a live attenuated, intranasal vaccine for otherwise healthy persons aged 2 to 49 years are currently licensed in the United States. Vaccines are available throughout the influenza season and most hospitals and facilities provides influenza vaccination to all their employees free of charge. Seasonal vaccine should be given each year in the fall, preferably October or November, before the influenza season. The antigenic composition of seasonal vaccines is reviewed annually so that these trivalent vaccines contain the most recently circulating strains, usually two subtypes of influenza A (H3N2, H1N1) and an influenza B virus. Both vaccine types are grown in eggs, and episodic production problems have sometimes led to shortages of the inactivated vaccine. For the 2010-2011 season, pandemic 2009 virus has been incorporated as the H1N1 component.

Seasonal influenza vaccines include trivalent and quadrivalent vaccines. Trivalent vaccines are derived from one A(H1N1), one A(H3N2), and one B vaccine virus strain. Quadrivalent vaccines contain same antigens as trivalent vaccines, plus additional B vaccine virus strain. If you work as a Nurse Assistant in Los Angeles, you are probably aware that the LA county department of public health requires that all healthcare personnel receive an annual influenza vaccination or wear a mask while working in patient care areas for the duration of the influenza season. The goal of the order is to lower the rates of transmission of influenza among healthcare personnel and the vulnerable populations that they serve. As a nurse assistant, getting vaccinated against influenza is the most effective way to protect yourself and your patients.





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Bradley, J. P., Bacharier, L. B., Bonfiglio, J., Schechtman, K. B., Strunk, R., Storch, G., & Catala, J. (2005). Severity of respiratory syncytial virus bronchiolitis is affected by cigarette smoke exposure and atopy

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