4.6 BCG (TB), Ebola Vaccines

Cause of Tuberculosis

Bacterium Mycobacterium tuberculosis

Symptoms of TB

Usually affects the lungs but can also affect the brain, spine, bones and kidneys

Significant wear on the body become frail and wasting

Incubation of TB

5% will develop active TB within 18-24 months

95% will develop latent TB

90% will never develop active disease

5% will have later reactivation

People at risk for getting TB

Travel to countries with high rates of TB

Duration of stay, close quarters, high-risk work (healthcare), consumption of unpasteurized milk and dairy

Plane travel is not a risk

Vaccine for TB

BCG vaccine

TB stats

Worldwide one third of the population is expected to be infected with TB

• Second leading cause of infectious death worldwide

• Canada has one of the lowest rates in the world

• Vaccine is not routinely used in Canada

BCG Vaccine Type and Route

Vaccine is live vaccine derived from mycobacterium bovis

Is administered SC

How long does BCG Vaccine last

Protection declines over time though studies have shown protection out to 60 years

BCG Recommendation in Canada, and what it is actually used for

Not generally recommended in Canada but may be administered to infants in high risk outbreak communities

• If used should be given as soon after birth as possible

Cannot be administered to immunocompromised individuals

BCG is used more in Canada to treat bladder cancer

Bacille Calmette-Guerin Vaccine (BCG) AEs

Usually results in ulceration in skin in about 50% of patients followed by a scar

• ~2-4% will develop keloid formation

Most reactions are generally mild

There 6 cases of deaths in first nations newborns linked to the vaccine from 1993 to 2003

• Linked to underlying undiagnosed immunodeficiencies in the infants

• This is why not routinely used in newborns and only in high-risk individuals and communities.

BCG Vaccine Contraindications

History of anaphylaxis to vaccine

Immunosuppression of any kind including treatment with corticosteroids.

Pregnancy defer until after birth

Positive TST

Cause of Ebola

RNA virus of Filoviridae Orthoebolavirus of the family 4 species cause human disease with Filoviridae Orthoebolavirus zairense (EBOV) causing Ebola virus disease (EVD) and is considered the most virulent

Reservoir is not fully understood but fruit bats are believed to be a natural host

Ebola Symptoms

Sudden onset flu-like (fever, myalgia, severe headache, and malaise) followed by worsening GI symptoms and fluid loss leading to electrolyte imbalances wasting and shock, Hemorrhage occurs in less than half of cases and is from the GI or other mucosa

Fatality rate is 25-90%

Virus can hide in immunologically privileged sites (testes, eyes, brain) for up to 40 months following clinical recovery

Full recovery can be associated with long term sequelae

Ebola Transmission

Typically, restricted to areas of Sub-Saharan Africa, with epidemics occurring in Central, West and East Africa •

Exposure to contaminated blood or body fluids from infected individual including sweat

Handling/preparing infected animals (particularly bats)

Exposure can occur from contaminated surfaces

Ebola Incubation

Incubation of 2-21 days, most show symptoms around 4-10 days

People at risk of getting ebola

Caring for EVD cases

Sexual contact with an EVD case

Pregnancy or breastfeeding (mother to child)

Unsafe burial practices

Handling or consuming bushmeat from affected areas

Ervebo vaccine (Restricted access to National Emergency Strategic Stockpile): Type of Vaccine

Live attenuated Ebola Zaire vaccine (EZV)

• Is a recombinant VSV (rVSV) based vaccine encoding for the Ebola virus glycoprotein

Ervebo vaccine Dose and Timing

Single dose 1ml IM indicated for healthy adults >18 years of age

For Pre and Post exposure, ideally within 72 hours of exposure but out to 10 days is possible

No information on booster doses though if 18 months from last dose for post- exposure treatment

Should not be give with other live or inactivated vaccines to prevent immune interference and monitor symptoms

Ervebo Vaccine Efficacy

No direct corelates of protection, does develop IgG and neutralizing Ab at 1 month last persist for 1-2 years

Protection has only been assessed in outbreaks and post-exposure due to nature of disease

• Does appear to show 100% effectiveness to this point but very limited evidence

Ervebo Contraindications

Hypersensitivity and previous anaphylaxis

Ervebo Precautions

Many dependent concerns of pregnancy, breastfeeding and immunocompromised

Not indicated generally for travelers

Ervebo AEs

Well, tolerated generally; Injection site pain, fever, headache, malaise and myalgia

• Some transient asymptomatic decreases in leukocytes in some recipients