RS11 - Parainfluenza Viruses and RSV

What is the family of human parainfluenza viruses (HPIVs)?

Paramyxoviridae

What is the genome of human parainfluenza viruses (HPIVs)?

ssRNA (-)

Are HPIVs enveloped or non-enveloped?

Enveloped

How many types of Human Parainfluenza viruses are there?

4 types

Which HPIV types cause severe lower respiratory tract infections?

Types 1–3 cause severe lower respiratory tract infections in infants and young children

How are Human Parainfluenza viruses transmitted?

Respiratory droplet, person-to-person contact, fomites

What is the incubation period for Parainfluenza viruses?

2–7 days

Who is most frequently infected with Parainfluenza viruses?

Frequently infects children <6 years

In whom is Parainfluenza disease more severe?

Disease is more severe in infants than adults

Why is croup more problematic in young children than adults?

Children have a narrower airway to begin with

What is the major disease caused by Parainfluenza viruses?

Major cause of Laryngotracheobronchitis (croup)

What is another name for croup?

Laryngotracheobronchitis

What percentage of children have had croup?

15% of kids have had croup

What percentage of children with croup require hospitalization?

2–4% of kids end up in hospital

What are the hallmark signs and symptoms of croup?

Labored, noisy breathing; stridor (narrowed airway); “Barking” cough; tissues in airway flap together; suprasternal retractions; usually worse at night

What mild respiratory illnesses can Parainfluenza viruses cause?

Mild upper respiratory tract infection (coryza, pharyngitis, mild bronchitis, wheezing, fever)

What severe lower respiratory diseases can Parainfluenza viruses cause?

Pneumonia or bronchiolitis

Can adults be infected with Parainfluenza viruses?

Yes. Reinfections occur in adults

Does Parainfluenza infection produce long-lasting immunity?

No long-lasting immunity; reinfections usually milder

How is croup treated?

Relief provided by single dose of steroid; steam (cool), cool mist humidifier; go out in cold air

Is there a vaccine for Parainfluenza viruses?

No vaccine

Are there specific antivirals for Parainfluenza viruses?

No specific antivirals

What type of virus is Respiratory Syncytial Virus (RSV)?

Family: Paramyxoviridae; ssRNA (-), Enveloped

How is RSV transmitted?

Respiratory droplet, person-to-person contact

What is the incubation period for RSV?

1–4 days

Why can RSV introduction into a nursery be devastating?

It is an important viral pathogen during the first year of life

What diseases are caused by RSV in infants?

Bronchiolitis and pneumonia in children <1 year old (most common cause)

What is the severe disease most associated with RSV?

Bronchiolitis (most common cause in children <1 in U.S.)

What other diseases can RSV cause?

Croup; upper respiratory tract infections in older children and adults; severe respiratory disease in adults over 65

What are the early symptoms of RSV infection?

Fever, rhinitis, pharyngitis, otitis

What symptoms develop in about one-third of RSV patients?

Wheezing, croup, cough, dyspnea (shortness of breath), retractions

What pathologic process causes bronchiolitis in RSV?

Increased mucus, sloughing of cells, plug the small airways

How does RSV spread between cells?

Spread by cell-to-cell fusion (syncytia formation)

What is RSV’s significance in infant mortality?

Most common cause of fatal acute respiratory tract infection in infants and young children

What symptoms may very young infants with RSV exhibit?

Irritability, decreased activity, breathing difficulties

What long-term respiratory issue is associated with RSV in some infants?

Recurrent wheezing; associations with asthma

Does RSV infection produce strong long-lasting immunity?

Immune response is not robust; reinfections usually less severe

Who is most at risk for severe RSV disease?

Babies <6 months old; premature or immunocompromised infants

How common is RSV hospitalization in infants under 6 months?

Two to three out of every 100 infants under 6 months are hospitalized with RSV every year

How common is RSV infection in early childhood?

Almost all children by age 2 will have had RSV infection

Which adults are at highest risk for severe RSV infection?

Adults 65 years and older; adults with chronic heart or lung disease; adults with weakened immune systems

What is the primary treatment for RSV in otherwise healthy infants?

Treatment is mainly supportive

What supportive treatments are used for severe RSV infection in children?

Oxygen, IV fluids, nebulized cold steam

Who should receive the RSV vaccine according to the CDC?

All adults ages 75 years and older; adults ages 60–74 years who are at increased risk of severe RSV

Is the RSV vaccine an annual vaccine?

No

What are the three licensed RSV vaccines for older adults?

GSK (Arexvy); Pfizer (Abrysvo); Moderna (mResvia)

What type of vaccine is Arexvy?

Recombinant pre-fusion F protein vaccine based on RSV-A subtype (Inactivated)

What type of vaccine is Abrysvo?

Recombinant pre-fusion F protein vaccine based on RSV-A and RSV-B subtypes (Inactivated)

What type of vaccine is mResvia?

Nucleoside modified mRNA encoding the RSV F glycoprotein stabilized in the prefusion conformation (pre-F protein)

When is the maternal RSV vaccine recommended?

Between 32 and 36 weeks pregnant during September through January in the US

How does maternal RSV vaccination protect the infant?

Generates antibodies that pass to the child and protect infant for first 6 months while at highest risk of severe disease

What reduction in hospitalization was seen in the Phase 3 maternal RSV vaccine trial?

Reduced risk of baby being hospitalized for RSV by 68% within 3 months after birth

What passive immunization is available for newborns against RSV?

Nirsevimab (Beyfortus), monoclonal antibodies

Who should receive RSV passive immunization?

Babies born to mothers who did not get a maternal RSV vaccine and a small group of young children (ages 8–19 months) at increased risk of severe RSV