Influenza A Subtypes and Antigenic Shift

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Questions and Answers

What is the reported fatality rate for avian influenza?

80%

70%

50%

60% (correct)

Where was the H5N1 avian influenza virus first identified in wild geese populations?

United States

China (correct)

Africa

Europe

Which of the following groups is NOT considered high-risk for influenza complications?

Pregnant women

Healthy adults aged 30-40 (correct)

Immunosuppressed individuals

Young children

What is the recommended vaccination schedule for children six months to eight years of age who have not received at least two doses of the influenza vaccine previously?

Two doses administered at least four weeks apart Signup and view all the answers

Which institution has residents that are considered high-risk for influenza complications?

Nursing homes Signup and view all the answers

What is the primary mode of transmission of H5N1 avian influenza virus?

Poultry-to-human contact Signup and view all the answers

What is the recommended annual influenza vaccination policy for all people?

Vaccination for all people six months and older Signup and view all the answers

Which of the following is NOT a high-risk group for influenza complications?

Healthy adults aged 20-30 Signup and view all the answers

What is the primary factor that contributes to the potential for wide-spread pandemics in influenza A subtypes?

Novel influenza subtypes with the potential to cause wide-spread pandemics Signup and view all the answers

What is the significance of the numbering system for influenza A subtypes, such as H3N2 or H5N1?

It characterizes the HA and NA proteins Signup and view all the answers

What was the estimated range of seasonal influenza activity in the United States from 2010 to 2018?

9.3 million to 49 million cases and 12,000 to 79,000 deaths per year Signup and view all the answers

What was the characteristic of the 2017-2018 influenza season?

It was the third most severe season since 2003-2004 Signup and view all the answers

What was the primary subtype responsible for most cases during the 2017-2018 influenza season?

A/H3N2 Signup and view all the answers

What is the significance of the author disclosure statement?

It indicates no relevant financial affiliations Signup and view all the answers

What is the purpose of the patient information section?

To offer handouts on preventing the flu and flu myths Signup and view all the answers

What is the source of the epidemiological data on influenza?

The American Academy of Family Physicians (AAFP) Signup and view all the answers

Who is the RIV vaccine not licensed for?

Children under 18 years old with no contraindications Signup and view all the answers

Which group of people should be targeted for vaccination efforts?

Healthcare professionals and those living with high-risk individuals Signup and view all the answers

When can LAIV be used in age-appropriate patients?

For the 2019-2020 influenza season Signup and view all the answers

What reduces the effectiveness of LAIV if given within a certain time frame?

Influenza-specific antiviral medications Signup and view all the answers

What is the AAFP's recommendation for influenza vaccination?

Preferential recommendation for vaccination with IIV Signup and view all the answers

What is the benefit of vaccination efforts in healthcare professionals?

Reducing the risk of influenza transmission to patients Signup and view all the answers

What percentage of patients with influenza experience severe disease due to viral or secondary bacterial pneumonia?

A minority of patients Signup and view all the answers

What is the primary purpose of influenza testing according to the CDC?

To modify management or when a patient with signs or symptoms of influenza is hospitalized Signup and view all the answers

What is the typical duration of an uncomplicated influenza infection?

Two to eight days Signup and view all the answers

What is the name of the adjuvanted inactivated trivalent vaccine licensed for use in adults 65 years and older?

Fluad Signup and view all the answers

What is the complication of influenza that is most common in children?

Gastrointestinal symptoms Signup and view all the answers

What is the purpose of a symptom-only clinical prediction rule for diagnosing influenza?

To aid clinicians in diagnosing influenza Signup and view all the answers

What is the term for the onset of influenza symptoms?

Rapid Signup and view all the answers

What is the complication of influenza that can occur in patients with medical comorbidities?

Exacerbation of a chronic disease Signup and view all the answers

What is the scoring system used in the symptom-only clinical prediction rule for diagnosing influenza?

2 points for fever and cough, 2 points for myalgias, 1 point for chills or sweats, and 1 point for symptom onset within the past 48 hours Signup and view all the answers

What is the term for the respiratory infection that can occur in patients with influenza?

Uncomplicated respiratory infection Signup and view all the answers

What is the title of the publication that reported on influenza activity in the United States during the 2018-19 season?

American Family Physician Signup and view all the answers

In which year did Moser et al. publish an article on an outbreak of influenza aboard a commercial airliner?

1979 Signup and view all the answers

What is the name of the publication that reported on the composition of the 2019-20 influenza vaccine?

MMWR Morb Mortal Wkly Rep Signup and view all the answers

Who wrote an article on human influenza virus infections?

Peteranderl et al. Signup and view all the answers

What is the name of the publication that reported on the clinical signs and symptoms of influenza?

Centers for Disease Control and Prevention Signup and view all the answers

In which year did Leekha et al. publish an article on the duration of influenza A virus shedding in hospitalized patients?

2007 Signup and view all the answers

Who wrote an article on the hidden burden of influenza?

Sellers et al. Signup and view all the answers

In which year did von Ranke et al. publish an article on infectious diseases causing diffuse alveolar hemorrhage in immunocompetent patients?

2013 Signup and view all the answers

Study Notes

Influenza

Antigenic shift occurs when there are significant changes in the HA or NA proteins, creating novel influenza subtypes with the potential to cause widespread pandemics.
Influenza A subtypes are characterized by numbering both the HA and NA proteins (e.g., H3N2, H5N1).
From 2010 to 2018, estimated seasonal influenza activity in the United States ranged from 9.3 million to 49 million cases and 12,000 to 79,000 deaths per year.
The 2017-2018 influenza season was the third most severe since 2003-2004, with high severity of disease in all age groups.

Epidemiology

Most cases were secondary to the A/H3N2 subtype, and low vaccine effectiveness was a significant contributing factor.
Cases predominantly involved young children exposed to swine, often at state fairs.
Institutionalized adults (e.g., residents of nursing homes or chronic care facilities), pregnant and postpartum women, and immunosuppressed people are at increased risk of complicated or severe influenza.

Prevention

The Centers for Disease Control and Prevention’s (CDC’s) Advisory Committee on Immunization Practices (ACIP) and the American Academy of Family Physicians (AAFP) recommend annual influenza vaccination for all people six months and older who do not have contraindications.
Vaccination efforts should target people at increased risk of complicated or severe influenza and those who care for or live with high-risk individuals, including health care professionals.
Multiple formulations of the influenza vaccine are available, including inactivated influenza vaccines (IIV), recombinant inactivated vaccine (RIV), and live, attenuated influenza vaccine (LAIV).

Clinical Manifestations and Complications

Influenza most often causes an uncomplicated respiratory infection with cough, fever, myalgias, chills or sweats, and malaise that persists for two to eight days.
Atypical gastrointestinal symptoms such as vomiting and diarrhea can occur in children.
Extrapulmonary complications are rare and can include cardiovascular, cerebrovascular, hematologic, musculoskeletal, neurologic, ocular, pulmonary, and renal complications.

Diagnostic Testing

Influenza testing can be considered when the results will modify management or when a patient with signs or symptoms of influenza is hospitalized.
A symptom-only clinical prediction rule may aid clinicians in diagnosing influenza, which assigns points for fever, cough, myalgias, chills or sweats, and symptom onset within the past 48 hours.

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Description

Learn about antigenic shift and its relation to novel influenza subtypes, HA and NA proteins, and pandemic potential.