LEARNING OBJECTIVES

Upon completion of this course, you will be able to:

• Describe novel H1N1 influenza and its transmission.
• List the clinical signs and symptoms associated with H1N1 influenza.
• Identify groups at high risk for complications.
• Discuss the types and uses of antivirals for the treatment of influenza.
• Explain appropriate infection control measures to prevent the spread of H1N1.

In July 2009, the World Health Organization (WHO) signaled that a global pandemic caused by the influenza virus A (H1N1) was underway. WHO's action was a reflection of the spread of the new H1N1 virus more than to the severity of illness caused by the virus. Though the disease was first reported in Mexico in the spring of 2009, soon more than 70 countries had reported cases of the infection. The United States continues to report the largest number of H1N1 cases of any country worldwide. The World Health Organization has confirmed over 4,000 deaths globally from H1N1, but experts agree that all estimates of the extent of the pandemic are grossly understated because so few patients are ever actually tested (WHO, 2009). Fortunately, most people recover without requiring medical treatment.

WHAT IS H1N1?

H1N1 is a hybrid flu, a disease that occurs when genes from animal influenza viruses mix with human influenza viruses. The new virus responsible for the H1N1 (swine) flu is believed to be a mix of pig, bird (avian), and human flu viruses. Hybrid flu viruses have caused pandemics twice in the past, in 1957 and 1968.

H1N1 influenza virus. (CDC.)

Unlike seasonal flu, H1N1 flu frequently causes severe disease in young adults and children. Evidence to date also suggests that population immunity to this virus is low, particularly among the young. Thus far, most cases of illness, hospitalization, and death associated with H1N1 infection have occurred among persons less than 65 years of age.

New research also reports that the H1N1 flu goes deeper into the lungs than ordinary seasonal flu, which targets cells in the nose, throat, and upper airway (Child et al., 2009). Researchers suspect this may explain why H1N1 flu can be so much more serious than seasonal flu.

Transmission

The H1N1 virus is transmitted in ways similar to other influenza viruses, mainly through the coughs and sneezes of people who are sick with the virus (i.e., via large-particle droplets). It may also be spread when people touch infected objects and then touch their nose or mouth. Since this is a new influenza virus in humans and most people do not have an immunity, transmission from infected persons to close contacts may be common.

Transmission via large-particle droplets requires close contact between source and recipient persons because droplets do not remain suspended in the air and generally travel only a short distance (less than 6 feet). All respiratory secretions and bodily fluids (diarrheal stool) of H1N1 cases should also be considered potentially infectious. Because data on the transmission of H1N1 viruses are limited, the potential for eye or gastrointestinal infection is unknown. H1N1 is not transmitted through eating food such as pork or pork products.

Infectious Period

Infected persons are assumed to be shedding virus from 1 day prior to illness onset until resolution of fever. In general, persons with H1N1 virus infection should be considered potentially infectious from 1 day before to 7 days following illness onset. Some persons who are infected may potentially be contagious for a longer period of up to 10 days (e.g., infants, immunosuppressed, and immunocompromised persons). (The estimated duration of viral shedding is based on that of seasonal influenza virus infection.)

Symptoms and Complications

H1N1 infection has been reported to cause a wide range of flu-like symptoms. Patients with uncomplicated disease due to confirmed H1N1 virus infection have experienced fever, chills, headache, upper respiratory tract symptoms (cough, sore throat, rhinorrhea, shortness of breath), myalgias, arthralgias, and fatigue. In addition, many people have also reported nausea, vomiting and/or diarrhea.

Expected complications may be similar to seasonal influenza:

• Exacerbation of underlying chronic medical conditions
• Upper respiratory tract disease (sinusitis, otitis media, croup)
• Lower respiratory tract disease (pneumonia, bronchiolitis, status asthmaticus)
• Cardiac conditions (myocarditis, pericarditis)
• Musculoskeletal conditions (myositis, rhabdomyolysis)
• Neurologic conditions (acute and post-infectious encephalopathy, encephalitis, febrile seizures, status epilepticus)
• Toxic shock syndrome
• Secondary bacterial pneumonia with or without sepsis

At the same time, autopsies on people who have died from H1N1 show that this virus is different from seasonal influenza, as reported by Dr. Sherif Zaki of the CD in September 2009 at U.S. Institute of Medicine meetings. H1N1 appears to damage the alveoli, the structures in the lung that deliver oxygen to the blood. This in turn may cause acute respiratory distress syndrome, an often fatal development that leaves patients gasping for breath.

High-risk Groups

Unlike seasonal influenza, where persons 65 years and older are most likely to be hospitalized or die from influenza-related complications, this age group has been substantially less affected by H1N1 virus than younger age groups. Widespread susceptibility to this virus among young persons and the potential for large numbers of cases raises the possibility of more hospitalizations and deaths, especially among younger age groups than would be expected for a typical routine seasonal influenza virus. Additionally, the study reported on by Dr. Zaki found that 90 percent of H1N1 fatalities were among patients with some other condition that would predispose them to serious disease.

For those who become infected by the virus, the same age and risk groups who are at higher risk for seasonal influenza complications should also be considered at higher risk for H1N1 influenza complications (see box).

Morbid obesity may also represent an additional risk factor for severe illness.

DIAGNOSING H1N1 INFLUENZA

Influenza-like-illness (ILI) is defined as fever (temperature of 100° F or greater) and a cough and/or sore throat in the absence of a known cause other than influenza.

A confirmed case of H1N1 virus infection is defined as a person with an influenza-like illness with laboratory results confirmed by a real-time RT-PCR test and/or a viral culture.

A probable case of H1N1 virus infection is defined as a person with an influenza-like-illness who is positive for influenza A, but negative for human H1 and H3 by influenza RT-PCR.

A suspected case of H1N1 virus infection is defined as a person who does not meet the confirmed or probable case definition, is not H1N1 test negative, and is either 1) a previously healthy person less than 65 years hospitalized for ILI, 2) has ILI and resides in a state without confirmed cases but has traveled to a state or country where there are one or more confirmed or probable cases, or 3) has ILI and has an epidemiologic link in the past 7 days to a confirmed case or probable case.

Testing for H1N1

Not all people with suspected H1N1 infection need to have the diagnosis confirmed, especially if the person resides in an affected area or if the illness is mild. Clinicians should be aware of local guidance on testing and should use their clinical judgment in addition to this guidance for deciding when to test for H1N1.

Clinicians should test persons for H1N1 virus if they have an acute febrile respiratory illness or sepsis-like syndrome. Certain groups may have atypical presentations, including infants, the elderly, and persons with compromised immune systems. Priority for testing includes persons who 1) require hospitalization or 2) are at high-risk for severe disease (as listed above).

To test for H1N1 influenza virus, upper respiratory specimens—such as a nasopharyngeal swab or aspirate, nasal swab plus a throat swab or nasal wash, or tracheal aspirate—should be collected. Bronchoalveolar lavage (BAL) and sputum specimens are also acceptable. Specimens should be placed into sterile viral transport media (VTM) and immediately placed on ice or cold packs or at 4° C (refrigerator) for transport to the laboratory. All respiratory specimens should be kept at 4° C for no longer than 4 days. Specimens should be sent to the state public health laboratory.

Real-time RT-PCR is the recommended test for confirmation of H1N1 cases. Clinicians should contact their state public health department if they test a person for H1N1 infection to obtain information on what clinical and epidemiological data to collect and specimen shipment protocols in their state.

Infection Control During Testing

Persons who perform nasal and tracheal aspirate collections on ill persons require appropriate personal protective equipment. This includes:

• Laboratory coat
• Gloves
• Eye protection
• Facemask

Work surfaces and equipment should be decontaminated with appropriate disinfectants as soon as possible after specimens are processed. Studies have shown that influenza viruses can survive on environmental surfaces and can infect a person for up to 2 to 8 hours after being deposited on the surfaces.

Several chemical disinfectants—including chlorine, alcohols, peroxygen, detergents, iodophors, quaternary ammonium, and phenolic compounds—are effective against human influenza viruses if used at the correct concentration for the appropriate contact time as specified in the manufacturer's recommendations.

TREATMENT OF H1N1

Antiviral Drugs

Treatment with certain antiviral drugs can make H1N1 flu symptoms less severe and help the patient recover more quickly. The CDC recommends the neuraminidase inhibitor antiviral medications Relenza (zanamivir) or Tamiflu (oseltamivir) for treatment and prevention of the H1N1 flu (see table below). These drugs may also help prevent serious flu-related complications.

These antiviral drugs are approved for treating the flu in patients 7 years and older and for preventing the disease in those 5 years and older. It is not recommended for use in people with underlying lung diseases such as asthma or chronic obstructive pulmonary disease (COPD).

Once the decision to administer antiviral treatment is made, treatment with zanamivir or oseltamivir should be initiated as soon as possible after the onset of symptoms. Evidence for benefits from antiviral treatment in studies of seasonal influenza is strongest when treatment is started within 48 hours of illness onset. However, some studies of oseltamivir treatment of hospitalized patients with seasonal influenza have indicated benefit, including reductions in mortality or duration of hospitalization stay, even for patients whose treatment was started more than 48 hours after illness onset. Recommended duration of treatment is five days. Antiviral doses recommended for treatment of novel H1N1 influenza virus infection in adults or children 1 year of age or older are the same as those recommended for seasonal influenza.

Healthcare providers should be aware of the lack of data on safety and dosing when considering oseltamivir use in a seriously ill young infant with confirmed H1N1 influenza virus infection or who has been exposed to a confirmed H1N1 influenza case and carefully monitor infants for adverse events when oseltamivir is used.

The H1N1 flu cannot be treated with amantadine (Symadine or Symmetrel) or rimantadine (Flumadine) because the virus is resistant to these drugs (CDC, 2009a).

Adverse events from influenza antiviral medications should be reported through the U.S. FDA Medwatch website (http://www.fda.gov/Safety/MedWatch/).

ANTIVIRAL MEDICATION DOSING RECOMMENDATIONS FOR H1N1 INFECTION

Medication/Group		Treatment (5 days)	Chemoprophylaxis (10 days)
Source: CDC, 2009.
Oseltamivir
Adults		75 mg twice per day	75-mg capsule once per day
Children ≥ 12 months	15 kg or less	30 mg twice per day	30 mg once per day
	16-23 kg	45 mg twice per day	45 mg once per day
	24-40 kg	60 mg twice per day	60 mg once per day
	>40 kg	75 mg twice per day	75 mg once per day
Children 6-11 months		25 mg twice daily	25 mg once daily
Children 3-5 months		20 mg twice daily	20 mg once daily
Children <3 months		12 mg twice daily	Not recommended unless situation judged critical due to limited data on use in this age group
Zanamivir
Adults		10 mg (two 5-mg inhalations) twice per day	10 mg (two 5-mg inhalations) once per day
Children		10 mg (two 5-mg inhalations) twice per day (age 7 years or older)	10 mg (two 5-mg inhalations) once per day (age 5 years or older)

Treatment for Symptoms

• Rest is important when treating flu symptoms.
• Drinking plenty of liquids is vital to preventing dehydration.
• Pain medications such as Ibuprofen or acetaminophen are normally taken to treat symptoms of flu such as body aches and fever.

Aspirin or aspirin-containing products (e.g., bismuth subsalicylate [Pepto Bismol]) should not be administered to any confirmed or suspected case of H1N1 virus infection aged 18 years and younger due to the risk of Reye's syndrome. For relief of fever, other anti-pyretic medications such as acetaminophen or nonsteroidal anti-inflammatory drugs are recommended.

Preventative Treatment for Control of H1N1 Influenza Outbreaks

Post-exposure antiviral chemoprophylaxis (the use of chemical agents to prevent disease) with either oseltamivir or zanamivir can be considered for the following:

• Close contacts of cases (confirmed, probable, or suspected) who are at high risk for complications of influenza
• Healthcare personnel, public health workers, or first responders who have had a recognized, unprotected close-contact exposure to a person with H1N1 influenza virus infection (confirmed, probable, or suspected) during that person's infectious period.

Pre-exposure antiviral chemoprophylaxis should only be used in limited circumstances and in consultation with public health authorities. Certain persons at ongoing occupational risk for exposure who are also at higher risk for complications of influenza (e.g., healthcare personnel, public health workers, or first responders who are working in communities with H1N1 outbreaks) should carefully follow guidelines for appropriate personal protective equipment or consider temporary reassignment.

To control outbreaks in nursing homes and other long-term care facilities, CDC recommends that ill patients be treated with oseltamivir or zanamivir and that prevention with either oseltamivir or zanamivir be started as early as possible to reduce the spread of the virus.

H1N1 VACCINE

Inactivated licensed H1N1 vaccine is available in single-dose syringes. (Children through 9 years of age require two injections, about a month apart, to ensure the appropriate immune response.) Live attenuated vaccine is also available in inhaler sprayers. Some inactivated vaccine contains the preservative thimerosal. Inhaler sprayer vaccine products are thimerosal-free. People with severe or life-threatening allergies to chicken eggs, or to any other substance in the vaccine, should not be vaccinated.

The seasonal flu vaccine and the H1N1 (swine) flu vaccine are separate vaccinations. The seasonal vaccine is not expected to protect against the H1N1 flu, and the H1N1 flu vaccine is not intended to replace the seasonal flu vaccine. Each protects against a different virus and is intended to be used alongside the other. Seasonal flu and H1N1 flu vaccines may be administered on the same day.

Who Should Be Vaccinated?

CDC's Advisory Committee on Immunization Practices (ACIP) has recommended that certain groups receive the 2009 H1N1 vaccine first (see table).

GROUPS RECOMMENDED TO GET 2009 H1N1 VACCINE

Inactivated (flu shot)	Live Attentuated (nasal spray)
Source: CDC Vaccine Information Statement, 2009.
Pregnant women People who live with or care for infants younger than 6 months of age Healthcare and emergency medical services personnel Persons between the ages of 6 months and 24 years Persons between the ages of 25 through 64 years who are at higher risk for H1N1 because of chronic medical conditions or a compromised immune systems	Persons between the ages of 2 and 24 years Persons between the ages of 25 and 64 years who: live with or care for infants younger than 6 months of age, or are healthcare or emergency medical personnel

Vaccine Availability

Many state health departments are partnering with private sector partners to ensure the H1N1 vaccine is delivered to as many recommended persons as rapidly as possible. The vaccine is available in a combination of settings, including public health–organized vaccination clinics and in private sector settings such as provider offices, retail settings, pharmacies, workplaces, and through community vaccinators. Private providers who wish to administer the H1N1 vaccine will need to enter into relationships with their public health department so that vaccine can be directed to them.

Monitoring Coverage, Safety, and Effectiveness

Clinicians should report adverse events and encourage patients to advise their healthcare provider if they experience any adverse events after receiving H1N1 vaccine. The Vaccine Adverse Event Reporting System (VAERS) (http://vaers.hhs.gov/esub/index), a national vaccine safety surveillance program co-sponsored by the CDC and the U.S. Food and Drug Administration, collects and analyzes information from reports of adverse events following immunization and is intended to serve as the foundation for safety monitoring. VAERS accepts reports from patients, providers, public health officials, and others. Additional strategies are being developed to actively monitor Guillain Barré Syndrome (GBS) incidence during the HINI influenza vaccination season with networks of providers set up for active case-finding.

INFECTION CONTROL IN THE HEALTHCARE SETTING

To prevent the transmission of all respiratory infections, including H1N1, in healthcare settings, infection control measures should be implemented at the first point of contact with a potentially infected person.

Facility Access Control and Screening

Facilities should have signage at entry points instructing patients and visitors about control and screening policies, including the need to notify staff immediately if they have signs and symptoms of flu. Facilities in communities where H1N1 influenza transmission is occurring should limit points of entry to the facility.

Healthcare facilities should establish mechanisms to screen patients for signs and symptoms of febrile respiratory illness at any point of entry to the facility. Provisions should be made to allow for prompt isolation and assessment of symptomatic patients. Screening of patients presenting to a medical facility should be done in a location with negative pressure air handling whenever feasible.

General Infection Control Measures

Infection-control recommendations should apply to all patients with febrile respiratory illness (defined as fever greater than 100° F) plus one or more of the following symptoms: nasal congestion, sore throat, or cough.

In areas with confirmed human cases of H1N1 virus infection, the risk for infection can be reduced through a combination of actions. No single action will provide complete protection, but an approach combining the following steps can help decrease the likelihood of transmission. These recommended actions are:

• Wash hands frequently with soap and water or use alcohol-based hand cleaner when soap and water are not available.
• Cover mouth and nose with a tissue when coughing or sneezing.
• Avoid touching the eyes, nose, and mouth.
• Avoid close contact (i.e., being within about 6 feet) with persons with ILI.

Routine cleaning and disinfection strategies used during influenza seasons can be applied to the environmental management of influenza. Management of laundry, utensils, and medical waste should also be performed in accordance with procedures followed for seasonal influenza.

Patient Placement and Transport

Any patients who have a confirmed, probable, or suspected case of H1N1 and present for care at healthcare facilities should be placed directly into individual rooms, and the door should be kept closed. Healthcare personnel who interact with the patients should follow the appropriate infection control procedures.

For procedures that are likely to generate aerosols (e.g., bronchoscopy, elective intubation, suctioning, administering nebulized medications), an airborne infection isolation room (AIIR) with negative pressure air handling with 6 to 12 air changes per hour can be used. Air can be exhausted directly outside or be recirculated after filtration by a high-efficiency particulate air (HEPA) filter. Facilities should monitor and document the proper negative-pressure function of AIIRs, including those in operating rooms, intensive-care units, emergency departments, and procedure rooms.

Procedures for transport of patients in isolation precautions should be followed. Facilities should also ensure that plans are in place to communicate information about suspected cases that are transferred to other departments in the facility (e.g., radiology, laboratory) and other facilities. The ill person should wear a surgical mask to contain secretions when outside of the patient room and should be encouraged to perform hand hygiene frequently and to follow respiratory hygiene/cough etiquette practices.

Isolation Precautions

All healthcare personnel who enter the patient's room should take standard Contact Precautions, and eye protection should be used for all patient-care activities for patients being evaluated or in isolation for H1N1. Maintain adherence to hand hygiene by washing with soap and water or using alcohol-based hand sanitizer immediately after removing gloves and other equipment and after any contact with respiratory secretions. Nonsterile gloves and gowns along with eye protection should be donned when entering a patient's room.

Isolation precautions should be continued for 7 days from symptom onset or until the resolution of symptoms, whichever is longer. Healthcare personnel entering the room of a patient in isolation should be limited to those performing direct patient care.

Respiratory Protection

Recommendations for the uses of facemasks and/or respirators vary for different settings where a person may be exposed to the H1N1 virus. These recommendations also differ based on whether the person exposed to H1N1 is in a group at increased risk for severe illness from influenza infection.

All healthcare personnel who enter the rooms of patients in isolation with confirmed, suspected, or probable H1N1 influenza should wear a fit-tested disposable N95 respirator or better. This recommendation differs from current infection control guidance for seasonal influenza, which recommends that healthcare personnel wear surgical masks for patient care. The rationale for the use of respiratory protection is that a more conservative approach is needed until more is known about the specific transmission characteristics of this new virus.

There are important differences between face masks and respirators. Face masks do not seal tightly to the face and are used to block large droplets from coming into contact with the wearer's mouth or nose. Most respirators (e.g., N95) are designed to seal tightly to the wearer's face and filter out very small particles that can be breathed in by the user.

When respiratory protection is required in an occupational setting, respirators must be used in the context of a comprehensive respiratory protection program as required under OSHA's Respiratory Protection Standard (29 CFR 1910.134). This includes fit testing, medical evaluation, and training of the worker.

Management of Visitors

Limit visitors for patients in isolation for H1N1 infection to persons who are necessary for the patient's emotional well-being and care. Visitors who have been in contact with the patient before and during hospitalization are a possible source of H1N1. Therefore, schedule and control visits to allow for appropriate screening for acute respiratory illness before entering the hospital and appropriate instruction on use of personal protective equipment and other precautions (e.g., hand hygiene, limiting surfaces touched) while in the patient's room. Visitors should be instructed to limit their movement within the facility. Visitors may be offered a gown, gloves, eye protection, and respiratory protection and should be instructed on their use before entering the patient's room.

Monitoring Healthcare Personnel

In communities where H1N1 virus transmission is occurring, healthcare personnel should be monitored daily for signs and symptoms of febrile respiratory illness. This includes healthcare personnel exposed to patients in an outpatient setting or the emergency department. Healthcare personnel who develop symptoms should be instructed not to report to work, or if at work, to cease patient-care activities and notify occupational health and infection control personnel. Asymptomatic healthcare personnel who have had an unprotected exposure to H1N1 may continue to work if they are started on antiviral prophylaxis.

Facilities should implement plans to ensure appropriate allocation of personal protective equipment, including N95 respirators and antiviral medications.

MANAGING AN INCREASED DEMAND FOR SERVICES

It is critical to assure medical offices and other outpatient facilities (e.g., outpatient/ambulatory clinics, outpatient surgery centers, urgent care centers, physical therapy/rehabilitation offices or clinics) that provide routine, episodic, and/or chronic healthcare services can manage an increased demand for services in the midst of a novel H1N1 influenza outbreak. Ensuring a sustainable community healthcare response will be important for a likely recurrence of H1N1 flu.

GET THE WILD IRIS NEWSLETTER!

• Security
• Privacy
• Site Map
• Help
• Wild Iris Home

EMS-CEU.com is a division of Wild Iris Medical Education

Copyright © 1999-2010 Wild Iris Medical Education, Inc.

Photograph © 2008 Jon Klein