RS12 - COVID19 and Influenza

Can influenza and COVID-19 be differentiated by symptoms alone?

Cannot tell the difference between influenza and COVID-19 based on symptoms alone. Need to test.

What is the primary route of SARS-CoV-2 and influenza transmission?

Predominantly by droplet and aerosol transmission.

Why does droplet and aerosol transmission require a lower infectious dose than surface transmission?

Surface transmission requires the virus to be outside of the body for a period of time and then requires transport to the lungs.

What produces droplets and aerosols that transmit respiratory viruses?

Breathing, speech, sneezing, coughing and certain medical procedures.

How far do respiratory droplets typically travel?

Droplets are larger than aerosols and usually fall to the ground within 3-6 feet (1-2m).

Why are aerosols especially dangerous for respiratory transmission?

Aerosols remain suspended in the air for an extended period of time and are more likely to get deep into lungs.

Which transmission route is the major route in healthcare settings?

Direct contact and droplet/aerosol transmission are major routes.

Why are healthcare providers vulnerable to respiratory infections?

Exposure to direct contact, indirect contact, droplets, aerosols, and aerosol-generating procedures.

Why is long-lasting immunity difficult for respiratory viruses?

Mucosal immunity does not last as long as systemic immunity (IgA vs IgG).

Why does intramuscular vaccination not provide strong mucosal immunity?

Vaccination via intramuscular injection primes strong systemic IgG responses but weaker/less durable mucosal IgA responses.

What family do coronaviruses belong to?

Coronaviridae.

What type of genome do coronaviruses have?

ssRNA (+), Enveloped.

What structural feature gives coronaviruses their name?

"Crown"-like glycoprotein spikes on surface.

What percentage of adult colds are caused by common coronaviruses?

~15% of adult colds.

What are the four common circulating human coronaviruses?

229E, NL63, OC43, HKU1.

What symptoms do common coronaviruses usually cause?

Runny nose, sore throat, headache, fever, cough, general feeling of being unwell.

Which coronaviruses have caused severe outbreaks since 2002?

SARS-CoV-1, MERS-CoV-1, SARS-CoV-2.

What receptor does SARS-CoV-2 bind to?

ACE2.

What antigen is targeted by COVID-19 vaccines?

Spike protein.

How do neutralizing antibodies protect against SARS-CoV-2?

Neutralizing antibodies directed toward the spike protein can prevent or limit infection.

What type of immunity do COVID-19 vaccines primarily provide?

Strong IgG protection, limited IgA protection.

How effective have recent COVID vaccines been against severe outcomes?

45-60% protection against severe outcomes like hospitalization and death.

What type of genome does influenza virus have?

8 negative-sense RNA gene segments.

How many proteins does influenza encode?

11 proteins.

What are the two major surface proteins of influenza?

Hemagglutinin (HA) and Neuraminidase (NA).

What is the function of hemagglutinin (HA)?

Binds cell receptors

neutralizing antibodies bind to HA and protect against infection.

What is the function of neuraminidase (NA)?

Aids in cell-cell spread by cleaving viral receptor so new virus can detach.

Which influenza protein is the target of vaccines?

HA is the target of influenza vaccines.

Which influenza protein is the target of antiviral drugs?

NA is a common target of influenza antiviral drugs.

Which influenza type can cause pandemics?

Influenza A.

Why can influenza A cause pandemics?

Infects multiple species and mutates rapidly.

Why does influenza B not cause pandemics?

Primarily infects humans and mutates more slowly.

What symptoms distinguish influenza from common colds?

Severe body aches, high fever and chills.

What is the contagious period for influenza?

1 day before symptoms develop and up to 5-7 days after becoming sick.

What is the major viral complication of influenza?

Viral pneumonia.

What causes secondary bacterial pneumonia after influenza?

Loss of mucociliary escalator and barrier function allowing bacteria to adhere and invade.

Why must influenza vaccines be updated annually?

Mutations alter HA antigen structure (antigenic drift).

What is antigenic drift?

Accumulation of small mutations that alter viral antigens and allow antibody escape.

What is antigenic shift?

Sudden major change in genome, very rare, can cause pandemics.

How can antigenic shift occur in influenza?

Exchange of gene segments between distantly related influenza viruses.

Why does antigenic shift cause pandemics?

No antibody protection against the new virus in the human population.

What is the natural reservoir of influenza A?

Birds.

What is H5N1?

High pathogenicity avian influenza strain.

Why is H5N1 currently considered low risk to the public?

No sustained human-to-human spread in the US to date.

What is the mortality rate of confirmed human H5N1 cases?

48% mortality.

What is an epidemic?

An outbreak of a condition that spreads over large geographic areas.

What is a pandemic?

An epidemic that has spread globally.

Why do RNA viruses mutate rapidly?

RNA polymerases are error-prone with limited proofreading activity.

How fast does influenza mutate compared to SARS-CoV-2?

Influenza mutates 2X as fast as SARS-CoV-2.

Why should someone get an influenza vaccine even if it is not 100% effective?

Even if it does not completely prevent illness, it can reduce severity of infection and reduce hospitalization and death.

How much can influenza vaccination reduce hospitalizations in pregnant women?

Reduce hospitalizations in pregnant women by 50%.

What is the mechanism of neuraminidase inhibitors?

Slow the virus's ability to spread from cell to cell.

Name two neuraminidase inhibitors used for influenza treatment?

Oseltamivir (Tamiflu) and Zanamivir (Relenza).

What is Baloxavir marboxil (Xofluza)?

An endonuclease inhibitor approved for patients 12 and older symptomatic for no more than 2 days.