COVID19/FLU

COVID19/FLU

Basic Virology…

Influenza Virology:

• RNA based virus 

• A and B sub types 

• Main Antigens: 

  • Hemagglutinin

  • Neuraminidase 

SARS-CoV-2 Virology 

• RNA virus 

• Main antigen = spike protein 

Antigenic Drift vs Shift

Antigenic Drift = small change, antibodies to similar virus less effective 

Antigenic Shift = large change

• No immunity in community 

• May result in epidemic/pandemic 

Flu Vaccine Considerations/Precautions…

1. 6 months to 8 years old: needs 2 doses for first influenza vaccine 

2. Egg allergy NOT anaphylaxis = no special precautions 

3. Egg allergy WITH anaphylaxis = must receive in hospital or doctors office NOT IN PHARAMCY

Signs and Symptons: Influenza 

• Sx onset: 1-4 days 

• Duration: 3-7 days 

• Contagiousness…

  • Starts 1 DAY before symptoms 

  • Most contagious in first 3-4 days 

  • Contagiousness abates with symptoms 

Signs and Symptoms: COVID-19

• Sx onset: 2-5 days

• Duration: highly variable 3-7 days

• Contagiousness…

  • Starts 2-3 DAYS before symptoms 

  • Most contagious 1 day before symptoms 

People at High Risk Flu/COVID-19

→ BOTH can result in severe illness and complications 

• Older adults > 65 years old 

• Complex comorbidiites: asthma, COPD, CKD, DM

• Immunocompromise 

• Pregnancy 

FLU: 

• Young children at higher risk of severe flu 

  • < 2 years old is AT VERY HIGH risk 

COVID-19: 

• Most mortality = older adults

• Longer recovery 

• Higher risk of clot, autoimmune issues 

Flu Approved Treatments:

1. Oseltamivir (Tamiflu) Neuraminidase Inhibitor 

   1. 75 mg PO BID for five days

2. Baloxavir (Xofluza) Endonuclease inhibitor 

   1. One dose = 2 caps 

   2. < 80 kg = 40 mg PO

   3. > 80 kg = 80 mg PO

COVID-19 Approved Treatments:

1. Outpatient…

   1. Nirmatrelvir/ritonavir (Paxlovid) Protease inhibitor 

      1. 300 mg/100 mg 3 tabs BID x 5 days

   2. Molnuiravir

2. Inpatient…

   1. Remdesivir (IV) Nuceloside analog chain terminator 

   2. Dexamethasone adjunctive

Flu Benefit of Treatment…

Most benefit if taken < 2 days of Signs and Symptoms

• Decreased hospitalization

COVID-19 Benefit of Treatment…

Most benefit within 5-10 days of signs and symptoms  

Who Should Get Antivirals?

1. High Priority

   1. Hospitalized patients 

   2. Severe or progressive diseases 

   3. Childrens < 2 years old 

   4. Adults => 65 years old 

   5. Pregnant women 

2. Consider Tx

   1. Outpatients with household contacts at risk 

   2. Outpatients with onset =< 2 days prior 

COVID-19 and Immunomodulators…

Used for patients who require O2 as a RESULT of COVID

• Extensive oxygen requirements: high-flow nasal cannula, CPAP, BiPAP

• Mechanical ventilation or ECMO (extracorporeal membrane oxygenation) 

  • Receive an immunomodulator with dexamethasone

• Baricitinib (PO) preferred

  • Tocilizumab (IV) alternative 

• USE BOTH Baricitinib and Tocilizumab for patients on ventilator or ECMO

Paxlovid (Nirmatrelvir/Ritonavir) Drug Interactions 

→ Ritonavir component (PK enhancer) 

• Strong CYP 3A4 and P-gp inhibitor 

• Antiarrhyhmic and anticonvulsant

Flu Special Population Tx

• Pediatrics 

  • Oseltamivir suspension age ≥ 0 years 

  • Baloxovir suspension age ≥ 25 years

• Pregnancy = Oseltamivir (tamiflu preferred) 

COVID-19 Special Population Tx

• Pediatrics

  • Remdesivir if ≥ 4 weeks old 

  • Paxlovid if ≥ 12 years old 

• Pregnancy: Remdesivir or Paxlovid 

Chemoprophylaxis…Flu/COVID

1. Influenza

   1. Oseltamivir for the entire flu season 

2. COVID-19

   1. For patients ≥ 12 with moderate to severe immunocompromised…

      1. Pemibivart