Lecture 7 - Nov 4 Flashcards
Menti: https://www.menti.com/alvixxuix3pc
Recall: viruses
-Genetic material contained in a biomaterial cover
-have dsDNA, ssDNA
-ssRNA (+/-)
-Follows the central dogma
-Genetic material determines method of replication
-The ‘cover’
-Viral capsid- gives the virus their characteristic shape
-Envelope- taking membranes from host cells to surround the capsid
-Must bind to a receptor to infect a cell
-Glycoprotein on the virus binds to the viral receptor on the target cell
Vaccination
-Basis of modern immunology
-Early strategy- deliberately cause a mild infection with an unmodified pathogen
-Discovered long-lasting protection çould be generated against infection
active vaccination
-Stimulating immune system to make memory B and -T cells (part of the adaptive immune response)
-They will fight off the pathogen when the body is exposed
-B cells make antibodies, T cells are cytotoxic or help activate B cells
-B cells
-Vaccine using some part of the pathogen is injected into the body (the toxin, an attenuated virus, parts of a virus, some of the genetic material that can make the epitope)
-B cells that recognize the epitope become activated (and continuously divides)
-B cells make the antibodies to fight the pathogen and makes memory cells for later use
-The memory cells are extremely sensitive and will act even quicker when exposed to the pathogen again (do not need co-stimulation)
T cells
Need to be exposed to antigen to be activated; can only be exposed to antigens when they’re presented on MHC molecules
MHC class 1 (presents intracellular antigens) = CD8 (cytotoxic) T cells
MHC class 2 (presents externally derived antigens) = CD4 (helper) T cells
Once co-stimulated, they divide and either become activated cytotoxic cells or memory cells (which do not require costimulation upon re-exposure)
Cytotoxic T cells use perforin and granzyme
Passive vaccination
Giving antibodies that interfere with the pathogen’s ability to infect
Does not tell the host cells to do anything, just helps it along
Antibodies opsonize (bind and cover the pathogen to make it more ‘appealing’ to be destroyed by macrophage), bind to target on viral surface, or marking it for destruction
MMR vaccine
A live attenuated vaccine
Live virus that has been weakened
Not safe for pregnancy- can offer in the immediate PP to protect any subsequent pregnancies against congenital rubella syndrome
Congenital rubella syndrome
Occurs with maternal exposure in 1st trimester
Get stats from slides
Many effects are on the heart and eyes
-fetal growth restriction appears to be the only sequela of 3rd trimester infection
-blueberry muffin rash
MMR vaccine
-live attenuated version of measles, mumps and rubella (weakend versions should stimulate immune system but not cause significant disease)
A live attenuated vaccine
Live virus that has been weakened
Not safe for pregnancy- can offer in the immediate PP to protect any subsequent pregnancies against congenital rubella syndrome
Congenital rubella syndrome
Occurs with maternal exposure in 1st trimester
Many effects are on the heart and eyes
Mode of action
Live attenuated version of all 3 viruses
A similar vaccine containing varicella zoster virus vaccine (MMRV)
Most of the population, once exposed to the vaccine, is immune for life- there is a small % of the population will need a booster, a very small % of the population will not gain immunity despite the number of vaccines they get
MMR vaccine in pregnancy
Only given PP
If someone didn’t know they were pregnant and got the vaccine, the chances are that they and the baby will be fine and the baby will most likely not have congenital rubella syndrome
Adverse effects
Injection site irritation
Flu like symptoms may occur about a week after
1-3 weeks later, swollen lymph nodes or aches may occur
Serious allergic reaction may occur
Do not give to people planning on becoming pregnant in the next 4 weeks
Varicella zoster virus (VZV)
Chicken pox, member of herpes family
Super contagious, chickenpox is transmitted through droplets
Shingles are also contagious
Must more serious when contracted as an adult
After primary infection, varicella becomes dormant in a nerve, and in later life can re-emerge as shingles
Will arise in the dermatome of the nerve it’s inhabiting is in supplies
Can re-emerge during times of high stress (including pregnancy or labour)
In a secondary infection, the immune system will take care of the virus (and chickenpox will not resurface)
We only test for titres when they’ve been exposed or don’t know if they’ve had it
Varicella vaccine
Live attenuated virus- offered immediate PP for people with low or no antibodies to protect the next pregnancy and future shingles
In the pregnant person, a primary infection is associated with life threatening pneumonitis (it’s much more severe in the general illness as well)
In the fetus, primary infection can cause congenital varicella syndrome or in the newborn, neonatal varicella syndrome
Can be fatal
Neonatal infection mainly occurs when maternal symptoms occur less than 5 days before to 2 days after delivery
VZIG
Passive immunity through immunoglobulins
Used when there’s a shingles outbreak in labour or when the baby may have been exposed
It’s a human blood product
IgG binds to VZV and inhibits the virus from starting an infection
Usually given IM
VZIG dosing and adverse effects
125U/kg, IM with max dose of 625U
Half life is 3 weeks
No preservations, mainly just pain at injection site
VZIG drug interactions
Theoretically unwise (and recommended to not do this) for them to have vaccines soon after the immune globulin as it may inhibit the ability of the attenuated virus to cause an immune response
Acyclovir can be used instead of VZIG if client does not want blood products (would want to consult OB, pediatrics, infectious disease)
Whooping cough
Extremely contagious
Aka ‘100 day cough’
Caused by a bacteria (Bordetella pertussis)
Infects the respiratory epithelium, secretes toxins to secrete mucous production and cause lymphocytosis
Very characteristic cough, inspiratory whoop, and fainting or vomiting after cough (because you can’t breath)
People break ribs, cause pneumothorax, tear their pleura
Associated with subconjunctival hemorrhage, urinary incontinence, etc
Extremely dangerous for babies
Tdap (ADACEL) is recommended for all pregnant people regardless of their immune status at 27-32 weeks GA
Fetus gets passive immunization
Provided as a 0.5mL dose, administered IM in deltoid
Influenza
Acute viral illness of respiratory tract caused by either A or B strain
Can range from mild to severe
Vaccination is recommended for all Canadians, pregnant people are consider a priority group
Antivirals are not a substitute for vaccination for prevention
Flu shot
New to midwifery scope of practice
Either trivalent or quadrivalent, vary in cost and production method
Cell culture and chicken egg production methods are common
Included strains change yearly based on data from the Southern hemisphere
May be given concurrently with any other vaccine
FLULAVAL TETRA (2024-2025)
Quadrivalent vaccine
Prepared from virus grown in eggs
0.5mL dose, 15mcg HA antigen from 4 different strains
Covid 19 vaccine
Viral illness of respiratory tract
Also a multi-system disease, depending on where ACE-II enzyme is expressed
Appears to be acute, many long-term conditions are also possible
We are still in the midst of a pandemic- has not been declared an endemic by the WHO yet
Vaccination is recommended for all eligible Canadians
Current recommendation = vaccination 6 months after last booster or known infection
Eligibility and recommendations are frequently updated, watch for updates from NACI and local public health agencies
Antivirals are not a substitute for vaccine for prevention
Current vaccine recommended for pregnant people is mRNA based
Pfizer and Moderna
Novavax is protein based
mRNA for the spike protein for the most prevalent strain currently in circulation
HSV
HSV-2 is the most common cause of genital herpes, bt HSV-1 is also becoming a cause for genital HSV infection
Determine through health history
Chronic infection characterized by clinical and subclinical recurrences (outbreaks)
Asymptomatic shedding of virus is frequent and transmission can occur whether or not an individual is symptomatic
Can cause severe disease in neonates
Untreated primary HSV infection in pregnancy carries a 30-50% risk in vertical transmission
Neonatal HSV
Infection at or near the time of delivery through exposure to the virus in genital tract
Rarely, iatrogenic or familial transmission after birth from lesions
Current management for someone who knows they have HSV: antiviral treatment from 36 weeks until delivery (Acyclovir), currently not the recommendation for people only with cold sores
HSV in the newborn
Type 1- skin, eye, mouth infection; rarely fatal; 30% of infants may go on to develop neurological sequelae
Type 2- CNS disease (encephalitis); with or without skin, eye, and mouth infection
Type 3- disseminated disease; 90% mortality rate if left untreated
If someone has an outbreak or prodrome of an outbreak at term (after the antiviral treatment), a C-section is recommended
Congenital HSV
Rare
Fetal acquisition in utero (TORCH) after primary infection
Antivirals for HSV
Acyclovir
Acyclovir is a purine nucleoside analog
Messes with viral DNA, prevents the enzyme that creates viral DNA from doing so
Valacyclovir
A prodrug of acyclovir- broken down in the gut or liver
Works the same way as acyclovir
Taken less often than acyclovir, but it’s more expensive
Same safety as acyclovir
Famciclovir
Only use if acyclovir and valacyclovir are inaccessible
We don’t know enough about it
Childhood vaccines
review note
