Exam 3_ Part 1

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Questions and Answers

What was the fatality rate of variolation compared to the variola major virus?

35% (correct)

10-15%

2-3% (correct)

1-2%

What was the role of cowpox in Edward Jenner's discovery?

It was a viral variant that caused smallpox outbreaks.

It was a less deadly disease used to enhance smallpox severity.

It was an alternative method of smallpox treatment.

It stimulated an immune response against the smallpox virus. (correct)

How many lives are estimated to be saved each year by current immunization programs according to WHO?

2-3 million (correct)

5 million

450,000

1-2 million

What is a significant concern related to the introduction of the smallpox vaccine?

It could lead to the development of cow parts. Signup and view all the answers

Which form of immunization do vaccines primarily represent?

Active Immunization Signup and view all the answers

What impact does vaccine hesitancy have on vaccine programs?

It can significantly reduce the vaccine program's efficacy. Signup and view all the answers

What type of immunity is conferred to a fetus through maternal circulation via the placenta?

Natural Passive Immunization Signup and view all the answers

What percentage of the population generally should have medical exemptions to vaccinations?

1% Signup and view all the answers

What is a common effect of vaccines on public health?

They reduce disease severity rather than prevent infection. Signup and view all the answers

What is the primary purpose of administering a modified form of a pathogen in active vaccination?

To induce a protective immune response Signup and view all the answers

Which of the following is a new active vaccine approved in 2023 for the prevention of Respiratory Syncytial Virus (RSV) disease during pregnancy?

ABRYSVO Signup and view all the answers

What was the risk of the variolation method in the 11th century?

It had a fatality rate of 35%. Signup and view all the answers

What is one challenge faced by vaccination campaigns in developing nations?

Ineffective vaccine distribution systems. Signup and view all the answers

What is a significant characteristic of artificially passive immunization?

Administers the products of the immune response Signup and view all the answers

Which treatment method uses plasma from survivors of a disease to provide immediate immune support?

Convalescent serum therapy Signup and view all the answers

What percentage of children are typically infected by Respiratory Syncytial Virus (RSV) by the age of 2 years?

Virtually all children Signup and view all the answers

What is a consequence of passive immunization conferred by maternal antibodies to infants?

Temporary protection for approximately six months Signup and view all the answers

What is a main feature of monoclonal antibodies used for COVID-19 treatment?

They are designed to target specific epitopes Signup and view all the answers

What is the expected need for hospitalization among children infected with RSV?

1-2% Signup and view all the answers

In which year was the RSV recombinant prefusion F protein vaccine trial conducted?

2023 Signup and view all the answers

What is a key benefit of vaccination in terms of public health?

It helps break the chain of transmission of diseases. Signup and view all the answers

Which type of immune response is characterized by the development of memory B and T cells?

Secondary immune response Signup and view all the answers

What distinguishes artificial passive vaccination from natural passive vaccination?

Artificial passive vaccination uses antibodies from external sources. Signup and view all the answers

What is the primary mechanism through which the smallpox vaccine provides protection?

By triggering a memory immune response. Signup and view all the answers

How do polysaccharide conjugate vaccines differ from traditional vaccines?

They combine polysaccharides with a protein to enhance immunogenicity. Signup and view all the answers

What factor does NOT influence the effectiveness of vaccination in interrupting disease transmission?

Socioeconomic status of the population Signup and view all the answers

What is the primary distinction between protection from disease and protection from infection?

Protection from disease prevents any symptoms from occurring. Signup and view all the answers

Which is NOT a component of active immunization?

Administration of antibodies Signup and view all the answers

In developing a protective immune response to a conjugate vaccine, what is a crucial aspect?

Generation of a strong long-term memory response. Signup and view all the answers

What effect did the pandemic have on the U.S. life expectancy in 2020?

It dropped by 1.5 years. Signup and view all the answers

What is the role of adjuvants in vaccines?

To enhance the immune response to the vaccine antigen Signup and view all the answers

In which case is the inactivated influenza vaccine (IIV) less effective?

In older adults Signup and view all the answers

What is a consequence of widespread vaccination of children with IIV?

It reduces mortality and illness in older adults Signup and view all the answers

What does the mRNA-based vaccine platform represent?

A novel approach never before licensed for a viral threat Signup and view all the answers

What was the significant event that occurred on January 12th, 2020?

The SARS-CoV-2 genomic sequence was deposited Signup and view all the answers

What is a unique feature of the oral polio vaccine?

It is an example of an attenuated vaccine Signup and view all the answers

How does vaccination affect community health regarding influenza?

It reduces the risk of transmission among populations Signup and view all the answers

What is a key characteristic of inactivated vaccines like the one for RSV?

They enhance immune response without replicating Signup and view all the answers

Why are new influenza vaccines urgently needed?

Influenza strains evolve rapidly Signup and view all the answers

What is the primary method of producing the inactivated influenza vaccine?

Growing the virus in embryonated chicken eggs Signup and view all the answers

What is a significant benefit of the high-dose influenza vaccine for older adults?

It is 24% more effective in individuals aged 65 and older Signup and view all the answers

How many strains are included in the inactivated influenza vaccine formula?

Four strains Signup and view all the answers

What is a correlate of protection for the influenza vaccine?

Serum antibodies to HA and NA Signup and view all the answers

What is a limitation faced when developing a pandemic influenza virus vaccine?

Production takes too long, often six months Signup and view all the answers

Which statement is true regarding the effectiveness of the influenza vaccine?

It has been shown to reduce hospital admissions for related illnesses by 74% Signup and view all the answers

What is the primary public health role of the inactivated influenza vaccine?

Reducing influenza-related morbidity and mortality Signup and view all the answers

What informs the strain selection for the seasonal influenza vaccine?

Surveillance of the Southern Hemisphere Signup and view all the answers

How many doses of influenza vaccine are manufactured annually in the US?

75-100 million doses Signup and view all the answers

What type of injection is the inactivated influenza vaccine administered through?

Intramuscular injection Signup and view all the answers

What is the primary reason for using inactivated polio vaccine (IPV) since 2000?

To minimize the risk of vaccine-derived paralytic poliomyelitis Signup and view all the answers

What was one consequence of the RSV vaccine candidate trial conducted in the 1960s?

It resulted in severe illness upon natural infection in vaccinated children Signup and view all the answers

How were the new oral polio vaccines designed to reduce the risk of mutation?

By reducing the ability to acquire mutations necessary for neuronal replication Signup and view all the answers

What principal risk is associated with attenuated vaccines in certain populations?

They require a stronger immune response to clear the infection. Signup and view all the answers

What is a potential risk associated with formalin-inactivated vaccines?

They may compromise the antigenicity of the pathogen Signup and view all the answers

Which mechanism allows the Oral Polio Vaccine (OPV) to generate both intestinal and systemic immunity?

It is delivered orally and replicates in gut-associated tissues. Signup and view all the answers

Which of the following cytokines is associated with the adverse effects experienced by children receiving the RSV vaccine candidate?

TH2 cytokines Signup and view all the answers

For which group is the Live Attenuated Influenza Vaccine (LAIV) not recommended?

Pregnant women Signup and view all the answers

What is a consequence of the attenuation process in vaccines like the OPV?

It can lead to the emergence of virulent strains if mutations occur. Signup and view all the answers

What mechanism do hemagglutinin (HA) and neuraminidase (NA) serve in the influenza virus?

They assist in the entry and release of viral particles Signup and view all the answers

Which populations should generally avoid live attenuated vaccines?

Expectant mothers and those with compromised immune systems. Signup and view all the answers

What is a potential drawback of using inactivated vaccines like the Sinovac COVID-19 vaccine?

Compromised antigenicity despite being non-replicating Signup and view all the answers

How is the efficacy and safety profile of mRNA vaccines like Pfizer/Moderna established?

By large-scale clinical trials followed by public distribution. Signup and view all the answers

What is the primary role of vaccine correlates of protection in vaccine development?

To identify immune responses associated with efficacy. Signup and view all the answers

What correlates of immune protection remain unclear regarding RSV vaccination?

The role of neutralizing antibodies to the F protein Signup and view all the answers

What is the primary indication for using inactivated influenza vaccination?

For anyone older than 6 months Signup and view all the answers

What method was used to attenuate the oral polio vaccine according to historical vaccine development?

Passaging the virus in animal cell cultures. Signup and view all the answers

What significant accomplishment is associated with the widespread use of the OPV?

The elimination of paralytic poliomyelitis from the U.S. Signup and view all the answers

What is a primary characteristic of mRNA vaccines in generating an immune response?

They cause the body to produce antibodies against the viral Spike protein. Signup and view all the answers

What role do prolines play in the SARS-CoV-2 spike protein?

They stabilize the spike in its pre-fusion form for better immune recognition. Signup and view all the answers

Which type of immune cells are primarily involved in the activation of the response to mRNA vaccines?

Dendritic cells. Signup and view all the answers

What is the significance of lipid nanoparticles in mRNA vaccines?

They serve as a delivery system for the mRNA into cells. Signup and view all the answers

What effect does the formation of memory B and T cells have on COVID-19 disease severity?

It generally reduces disease severity during future infections. Signup and view all the answers

Which characteristic is NOT associated with replication-competent 'live' attenuated vaccines?

They require a very high dosage to be effective Signup and view all the answers

What is one of the functions of adjuvants added to vaccines?

Enhance antigen presentation Signup and view all the answers

Which of the following individuals is considered to be at high risk for severe influenza disease?

A woman in her second trimester of pregnancy Signup and view all the answers

The concept known as 'herd immunity' is characterized by?

Protection afforded to unvaccinated individuals due to the high immunity levels within the community Signup and view all the answers

Inactivated vaccines are characterized by?

Are made from infectious agents that cannot replicate Signup and view all the answers

What type of vaccine has been created by isolating and inserting a gene into an expression vector for antigen production?

Recombinant subunit vaccine Signup and view all the answers

What critical role do the COVID-19 vaccines developed by Pfizer/BioNtech and Moderna play?

They utilize mRNA technology to elicit an immune response Signup and view all the answers

Which statement is true regarding the role of adjuvants in vaccination?

They help sustain a prolonged immune response Signup and view all the answers

What type of immune response is typically expected following a vaccination?

Development of memory B and T cells Signup and view all the answers

Which factor does NOT typically influence the effectiveness of vaccination against infectious diseases?

Historical events related to medical advancements Signup and view all the answers

Study Notes

Vaccine History and Societal Impact

Vaccination mobilizes the host immune system to prevent disease.
Vaccination helps break the chain of disease transmission.
Variolation, a practice of deliberate nasal inoculation with dried smallpox scabs, was used in China in the 11th century.
Edward Jenner, in 1796, was the first to use cowpox to protect against smallpox.
The smallpox vaccine was a major contributor to the eradication of smallpox, saving an estimated ~5 million lives annually.
As soon as the smallpox vaccine became available, concerns arose about developing "cow parts" following vaccination.
The World Health Organization estimates that current immunization programs save 2-3 million lives annually.
Vaccine inequality exists, with developing nations often having limited access or less effective vaccines for certain diseases like rubella, measles, and rotavirus.

Passive vs. Active Immunization

Passive immunization involves administering the products of the immune response, such as antibodies, providing short-term protection.
Active vaccination involves administering a modified form of the pathogen or its derivatives, inducing long-term immunity.

Natural Passive Immunization

IgG from maternal circulation is passively transmitted to the fetus in utero through the placenta.
IgG levels decline slowly after birth.
Vaccination of pregnant women can protect the baby during the first 6 months of life.

Respiratory Syncytial Virus

Respiratory Syncytial Virus (RSV) can cause severe respiratory illness, such as bronchiolitis or pneumonia.
Nearly all children become infected with RSV by the age of 2.
1-2% of children with RSV require hospitalization, which may involve oxygen, intubation, or mechanical ventilation.

Prevention of RSV Disease

Active Vaccine:
- ABRYSVO (introduced in 2023) is a recombinant prefusion F protein vaccine given during pregnancy.
- Clinical trials demonstrated its efficacy in protecting infants from lower respiratory tract illness.
- Recommended for use during RSV season at 32-36 weeks gestation.
Artificial Passive Immunity:
- Nirsevima (introduced in 2023) is a monoclonal antibody approved for infants.

Artificial Passive Immunization: Convalescent Serum

Convalescent serum, rich in antibodies from individuals who have recovered from a disease, has historically been used to treat emerging infectious diseases.
In the 1960s, a virologist who contracted Lassa virus was successfully treated with plasma from a recovered nurse.

Convalescent Plasma and Monoclonal Antibodies for COVID-19 Treatment or Prevention

Plasma is the liquid portion of blood remaining after the cells are removed.
Monoclonal antibodies, targeting specific epitopes, can block infection.
Both convalescent plasma and monoclonal antibodies were employed in the early stages of the COVID-19 pandemic, before the emergence of resistant variants.

Attenuated Vaccines

Replication-competent, attenuated vaccines induce a memory immune response similar to natural infection.
Examples of attenuated vaccines: Oral Polio Vaccine (OPV)
Attenuated vaccines are contraindicated in pregnancy and immunocompromised individuals due to the need for an immune response to clear the infection.
It is safe to administer attenuated vaccines to people living with HIV with CD4 T cell count > 200 cells/mm3.
OPV was attenuated by passing the virus in monkey kidney cells and replicates in gut-associated tissues.
Attenuation of poliovirus neurovirulence often involves changing a few nucleotides in the 5'UTR of viral RNA.
In rare cases, the vaccine-attenuating mutations can revert to the original form of the virus (wild-type) leading to paralytic poliomyelitis.

Inactivated Vaccines

Inactivated vaccines use chemical procedures to inactivate the pathogen.
Inactivated vaccines are safer for pregnant and immunocompromised individuals.
Examples of inactivated vaccines: Sinovac COVID-19 vaccine CoronaVac, Inactivated influenza vaccines.

The Tragedy of the RSV Vaccine Candidate

A formalin-inactivated RSV vaccine candidate tested in the 1960s resulted in enhanced respiratory disease (ERD) in vaccinated children.
80% of children who received the vaccine experienced serious disease compared to 5% of placebo recipients.
The vaccine primed the immune system for a severe response, leading to increased illness upon natural RSV infection.
The ERD likely resulted from a TH2-driven immune response characterized by pulmonary eosinophilia and non-neutralizing antibodies.
Correlates of protection for RSV likely involve TH1-driven immune responses and neutralizing antibodies against the F protein.

Influenza Vaccines

Inactivated influenza vaccines (IIV) are recommended for everyone > 6 months old.
Live attenuated influenza vaccine (LAIV) is available as a nasal spray for ages 2-49 in immunocompetent, non-pregnant individuals.
Influenza virus HA binds to sialic acid for entry, while NA cleaves HA-sialic acid for viral release.
IIV is the cornerstone of public health in the US, formulated annually with 4 strains of influenza virus.
Correlates of protection against influenza involve serum antibodies to HA and NA.
Widespread vaccination with IIV reduces mortality and illness in older adults.
IIV reduces transmission between animals in a guinea pig model.
There is a 6 month delay for pandemic influenza vaccine production, highlighting the need for better rapid manufacturing methods.

mRNA vaccines

mRNA vaccines use DNA encoding the antigen of interest, packaged into lipid nanoparticles.
The COVID-19 mRNA vaccines (Pfizer-BioNTech and Moderna) encode for the pre-fusion spike protein of SARS-CoV-2.
mRNA vaccines are injected into muscle, where DCs take up the mRNA and synthesize the viral antigen, triggering an immune response.
mRNA COVID-19 vaccines reduce disease severity upon SARS-CoV-2 infection.
The Pfizer-BioNTech COVID-19 vaccine (BNT162b2) has demonstrated long-term memory B and T cell formation that offer protection against severe disease.
Pfizer-BioNTech and Moderna mRNA vaccines offer a rapid and scalable manufacturing process, excellent safety profile, and immunogenicity.
They are a promising new class of vaccine with the potential to address future infectious disease threats.

Characteristics of Live Attenuated Vaccines

These vaccines can reversion back to a virulent pathogen
They are generated by passaging a pathogen in human cells

Adjuvants

These adjuvants are added to vaccines to enhance antigen presentation

High-Risk Groups for Seasonal Influenza

A woman in her second trimester of pregnancy is considered high-risk
A 7-month old male living in Arizona is considered high-risk
A 72-year-old female in relatively good health is considered high-risk

Herd Immunity

This concept is known as herd immunity