Infectious Disease: Differentiating Viral Infections 

Norovirus 

Avian (Bird) Flu 

(Seasonal) Influenza 

Respiratory Syncytial Virus (RSV) 

COVID-19 

Defining symptoms 

Severe gastrointestinal symptoms (i.e., nausea/vomiting, diarrhea, and abdominal cramps) 

Common: Conjunctivitis, fever, body aches, fatigue, cough, sore throat 

Rare: seizure, diarrhea 

Body aches, fatigue, fever, sore throat 

Wheezing, coryza, fever, congestion 

Loss of taste or smell, fever, sore throat, congestion, muscle aches, fatigue 

High-risk populations 

High risk for contraction: 

• Children: 6-18 months at daycare 

• Geriatric: in nursing homes 

• Other: Immunocompromised 

High exposure risk: Occupational contact (e.g. cattle or poultry workers, contact with wild birds) 

High risk of complications: children <5 years, adults ≥65 years, pregnant people, certain chronic conditions (e.g., chronic lung diseases, heard disease, kidney disease, liver disorders, HIV/AIDS) 

High risk of complications: premature infants, adults ≥75 years, certain conditions (e.g. chronic lung conditions, congenital heart disease, neuromuscular disorders) 

High risk of complications: adults ≥65 years,  infants <6 months, respiratory conditions, cardiovascular conditions, chronic kidney disease 

Complications 

• Electrolyte imbalance 

• Severe dehydration 

• Gastrointestinal bleeding 

• Renal failure 

• Pneumonia 

• Acute respiratory distress 

• Respiratory failure 

• Sepsis 

• Myocarditis 

• Encephalitis 

• Rhabdomyolysis 

• Multi-organ failure 

• Pneumonia 

• Bronchiolitis 

• Respiratory failure 

• Acute: Pneumonia, acute respiratory distress syndrome, multi-organ failure 

• Long-term: Long COVID 

Treatment 

• Supportive care: Oral or intravenous rehydration 

• Antibiotics (limited to severe cases or in the presence of a known pathogen) 

• Oseltamivir BID X 5 days (14 days and older) 

• Baloxavir marboxil single dose (5 years and older) 

• Supportive care (i.e., antipyretics) 

• Oseltamivir BID X 5 days (14 days and older) 

• Zanamivir BID X 5 days (7 years and older) 

• Peramivir (6 months and older) 

• Baloxavir marboxil single dose (5 years and older) 

• Supportive care (e.g., antipyretics) 

• Supportive care (e.g., rehydration, antipyretics, decongestants, bronchodilation [e.g. albuterol], corticosteroids [e.g. dexamethasone]) 

• High-risk patients: Palivizumab, nirsevimab, ribavirin 

• Nirmatrelvir/Ritonavir (Paxlovid; Aged ≥12 years and ≥40 kg) 

• Remdesivir (Aged ≥28 days and ≥3 kg) 

• Molnupiravir (Adults) 

• Convalescent plasma 

• Supportive care 

Clinical Considerations 

• Loperamide may worsen symptoms (not recommended) 

• Requires Contact Precaution 

• Amantadine and rimantadine are not recommended due to drug resistance 

• Oseltamivir drug-drug interactions: methotrexate, entecavir, trospium 

• Zanamivir: contraindicated in asthma/chronic obstructive pulmonary disorder (COPD) patients 

• Pregnant patients should receive Abrysvo® between September and January for most parts of the US 

• Severe liver and kidney contraindications with Paxlovid 

• Avoid molnupiravir in pregnancy and use contraception during drug administration