21 - Vaccine Hesitancy Flashcards
(30 cards)
What is vaccine hesitancy?
Refers to delay in acceptance or refusal of vaccines despite availability of vaccine services
Complex and context specific varying across time, place and vaccines
Vaccine preventable diseases in developed countries reduced by..
98-99%
Decline in measles mortality in developed countries
78% decline, 12.7 million deaths avoided
However, it has risen 30% globally
What diseases are eradicated?
- Small pox (20-60% death rate, 300-500 million deaths in 20th century)
- Rinderpest
Getting close: polio
What is disease elimination? E.g.
Local elimination
e.g. measles, mumps and rubella in NA and EU
What is rinderpest? Transmission? Status?
Cattle plague (domestic cattle, water buffalo, yaks)
Animal to animal contact, virus present in nasal secretions preclinically
Global vaccination program = last case 2001, eradication declared 2010
What is the MMR vaccine? Introduced when
Measles, mumps and rubella
Introduced in 1970
In Canada, adults born before 197o are presumed to have acquired natural immunity to MM
Describe measles
MeV
RNA virus
High R0 (12-18)
High level population immunity required
Describe mumps
MuV
RNA virus
R0 3.5-4.5
Increase in cases since 2006
Describe rubella
RuV
RNA virus
R0 3.7-7.8
Infection of pregnant women = high likelihood of birth defects
What is herd immunity? Diseases with high R0…
Reduction in disease incidence in unvaccinated individuals when sufficient proportion of pop is vaccinated
High R0 requires higher coverage to attain herd protection
Flu vaccination reduces risk of influenza by… Why is there variable protection?
Between 40 and 60%
Does the vaccine line up with the circulating influenza virus? Vaccines are made well before flu season
Describe polio? Incubation, serotypes of polio
Non-zoonotic, humans only, spread through fecal-oral route
<1% have paralytic polio
Incubation period 7-10 days
Wild poliovirus type 1 (WPV1)
Wild poliovirus type 2 (eradicated)
Wild poliovirus type 3 (eradicated)
What was the lubeck disaster
1929 Lubeck, Germany
BCG (TB) vaccine to newborns orally
251 infants inoculated
91% developed evidence of TB
77 deaths
Cause: contamination of BCG vaccine w virulent M. tuberculosis
Describe “The Cutter Incident”
- polio vaccine in 1955
- flaw in polio vaccine manufacturing process
- Rushed manufacturing, Cutter laboratories produced live polio virus in “inactivated” vaccine
- 120,000 vaccinated with it
- 40,000 cases of polio
- 56 paralyzed, 5 dead
Cutter incident led to…
- regulatory changes
- implementation of much more vigilant monitoring and regulation of the vaccine industry
Two types of polio vaccines
- inactivated polio vaccine
- oral polio vaccine
Describe OPV
- live weakened (genetically modified) poliovirus
- occasionally mutates to form similar to wild polio and causes paralysis
- Canada stopped using in 1996
- transmission in areas of poor sanitation, low vaccination rate
After suspension of Dengvaxia, immunization rates for what diseases went down?
Polio, chicken pox, tetanus, others
Describe trends in Samoa MMR vaccination rates
- 2017 = 75% coverage
- 2018 = ~40% coverage
- July 2018: 2 deaths (children) due to improper reconstitution of vaccine (atracurium used as diluent instead of water)
- increase in # measles deaths
Re-emergence of measles in the US
- majority of ppl who got it were unvaccinated
- still common in many parts of world
- travelers with measles continue to bring the disease into US
- spread in groups of unvaccinated ppl
Measles in Canada. Why could it be a future threat?
Eliminated in 1998 (transmission within country or region no longer active)
But, imported cases AND coverage below minimum needed to maintain measles elimination
(1st dose coverage = 90%, required 95% of pop)
Describe the Montreal Vaccine Riots
- March 1885: Smallpox brought to city
- Mass vaccinations attempted, but several cases of erysipelas = suspended for 3 mo
- Sept = 6000 cases of smallpox
- Poor forcibly removed from housing
- vaccinations compulsory
- protests, riots, firing at police
- 3234 deaths due to smallpox
Rationales behind vaccine hesitancy (9)
- Complacency (unlikely to be exposed to virus e.g. measles)
- Mistrust of government, science
- Religious beliefs
- Injection of viral components/foreign substances
- Disease disappearing for other reaons
- Risk>benefit
- Alternative therapies
- Autism
- History of distrust
