Assuring-health-coverage-for-all-in-India

1. Understanding the
Varicella-Zoster Virus
(VZV) Vaccine

2. Agenda
• Introduction to VZV
• History of VZV Vaccine
• VZV and Chickenpox
• VZV and Shingles
• VZV Vaccine Types
• Vaccine Efficacy
• Vaccine Schedule
• Vaccine Safety
• Herd Immunity
• Conclusion

3. Introduction to VZV
• Varicella-Zoster Virus (VZV) is a highly contagious virus belonging to the
herpesvirus family.
• VZV has a dual role in causing two distinct diseases: chickenpox and shingles.
• Chickenpox, also known as varicella, is primarily a childhood illness
characterized by a characteristic itchy rash, fever, and flu-like symptoms.
• Shingles, or herpes zoster, occurs when the virus reactivates later in life,
causing a painful rash with blisters.
• VZV remains dormant in nerve cells after the initial infection and can reactivate
years or even decades later.
• The impact of VZV on public health is significant due to the prevalence of these
diseases and the potential for severe complications in vulnerable populations.

4. History of VZV Vaccine
• The development of the VZV vaccine began in the mid-20th century.
• Key milestones in vaccine development:
• 1960s: Isolation of the Varicella-Zoster Virus (VZV) laid the foundation for vaccine development.
• 1974: The first live attenuated VZV vaccine was tested in clinical trials.
• 1980: Japan became the first country to license a VZV vaccine for widespread use.
• 1995: The United States introduced the Varivax vaccine for chickenpox.
• 2006: The introduction of the Zostavax vaccine for shingles.
• 2017: The introduction of Shingrix, a more effective recombinant vaccine for shingles.
• The VZV vaccine has been incorporated into routine immunization schedules worldwide to prevent
both chickenpox and shingles.
• It has contributed significantly to reducing the burden of VZV-related diseases and their associated
complications.

5. Varicella-Zoster Virus (VZV) and Chickenpox
• Varicella-Zoster Virus (VZV) is the causative agent of chickenpox, also
known as varicella.
How VZV causes chickenpox:
• VZV is transmitted through
respiratory droplets or direct
contact with the rash of an infected
person.
• It initially infects the respiratory
tract and then spreads throughout
the body via the bloodstream.
• The virus ultimately causes a
characteristic itchy rash and fever.
Symptoms of chickenpox:
Rash with small, itchy blisters.
Fever, headache, and fatigue.
Loss of appetite and general discomfort.
Complications of chickenpox:
• Secondary bacterial infections of
skin lesions.
• Pneumonia, especially in adults
and immunocompromised
individuals.
• Encephalitis (inflammation of the
brain).
• Rare but serious complications in
infants, pregnant women, and
immunocompromised individuals.
Prevalence before the vaccine:
• Chickenpox was once a common
childhood illness, with nearly everyone
experiencing it.
• In the United States alone, there were
about 4 million cases annually before the
vaccine's introduction.
• High morbidity rates and occasional
severe outcomes made it a significant
public health concern.

6. Varicella-Zoster Virus (VZV) and Shingles
Varicella-Zoster Virus (VZV) can reactivate later in life, causing shingles (herpes zoster)
Reactivation process:
• After an initial VZV infection
(chickenpox), the virus remains
dormant in nerve cells.
• Reactivation can occur when the
immune system weakens due to
aging, illness, stress, or other
factors.
• The virus travels along nerve
pathways to the skin, resulting in a
painful rash.
Symptoms of shingles:
• Pain, burning, or tingling in a specific
area of the body.
• Development of a rash with red, fluid-
filled blisters.
• Itching, fever, and general malaise.
Complications of shingles:
• Postherpetic neuralgia: Persistent,
severe pain in the area where the
rash occurred.
• Scarring and skin discoloration.
• Eye complications if the virus
affects the eyes.
• Neurological complications in
some cases.
Risk factors for shingles:
• Advancing age, as the risk increases
significantly after 50.
• Weakened immune system due to
conditions like HIV/AIDS or
immunosuppressive medications.
• Stress, which can weaken the immune
system.
• Previous history of chickenpox (VZV
infection).

7. Types of Varicella-Zoster Virus (VZV) Vaccines
There are two primary types of VZV vaccines available
Live Attenuated Vaccines
• Notable example: Varivax
• These vaccines contain a weakened,
live form of the virus.
• They mimic a natural VZV infection,
stimulating the immune system to
build immunity.
• Typically administered as a single or
two-dose regimen, depending on age
and risk factors.
• Varivax is widely used for chickenpox
prevention in children.
Recombinant Vaccines
• Notable example: Shingrix
• These vaccines do not contain live virus.
• They use pieces of the virus or specific viral
proteins to stimulate a strong immune
response.
• Shingrix is a recombinant vaccine developed
for the prevention of shingles (herpes
zoster) in adults.
• It is highly effective and recommended for
adults over 50, even if they've had
chickenpox or received the older live
vaccine.
The choice between live attenuated and recombinant vaccines depends on factors such as age, health
status, and the specific disease (chickenpox or shingles) being targeted.

8. Effectiveness of VZV Vaccines
oster Virus (VZV) vaccines have demonstrated high effectiveness in preventing both chickenpox a
Chickenpox Vaccine Efficacy:
• Clinical trials have shown that the
live attenuated vaccines, such as
Varivax:
• Are approximately 90% effective
in preventing chickenpox after
one dose.
• Are over 95% effective after the
recommended two-dose
regimen.
• Offer significant protection
against severe chickenpox cases
and complications.
Shingles Vaccine Efficacy:
• Shingrix, the recombinant shingles vaccine, has
shown impressive efficacy in clinical trials:
• Reduces the risk of shingles by more than 90% in
individuals aged 50 and older.
• Provides long-lasting protection against shingles,
even in older age groups.
• Significantly reduces the risk of postherpetic
neuralgia, a common and painful complication of
shingles.
• These efficacy rates demonstrate the value of VZV
vaccines in preventing VZV-related diseases and
their complications.
• Real-world studies have confirmed the vaccines'
effectiveness and their positive impact on public
health.

9. Varicella-Zoster Virus (VZV) Vaccine Schedule
Booster Shots (if applicable):
• Currently, booster shots for the chickenpox vaccine are not routinely recommended.
• Shingrix, however, may require booster shots in the future as more data become available.
• Stay informed about the latest recommendations from healthcare authorities regarding booster
doses.
• Understanding the recommended schedules and dosing intervals is vital to ensure individuals
receive the full benefits of VZV vaccination.
For Children (Chickenpox):
• The recommended vaccination schedule for
children typically includes:
• First dose: Around 12-15 months of age.
• Second dose: Given at 4-6 years old.
• A two-dose regimen is essential for
ensuring long-term protection.
For Adults (Shingles):
• Shingrix, the shingles vaccine, is
recommended for adults aged 50 and older.
• The vaccination schedule includes:
• Two doses of Shingrix, administered 2 to 6
months apart.
• The second dose is necessary to maximize
and prolong protection.

10. Safety of Varicella-Zoster
Virus (VZV) Vaccines
Safety Profile: VZV vaccines, both live attenuated (e.g., Varivax) and
recombinant (e.g., Shingrix), have a well-established safety profile.
Common Side Effects:
• Side effects are generally mild and short-lived. They may include:
• Soreness or redness at the injection site.
• Low-grade fever.
• Mild rash or itching.
• Fatigue or headache.
• These side effects usually resolve on their own within a few days.

11. Safety of Varicella-Zoster
Virus (VZV) Vaccines
Rare but Serious Adverse Events:
• Severe allergic reactions (anaphylaxis), which occur in very few cases.
• Febrile seizures (associated with Varivax), which are also extremely rare.
• Serious neurological events, such as encephalitis or Guillain-Barré Syndrome,
have been reported but are exceedingly rare.
• It's important to note that the risk of these rare events is significantly outweighed
by the benefits of vaccination in preventing chickenpox and shingles.
• Healthcare providers carefully assess an individual's medical history and current
health status to determine if vaccination is appropriate.
• Continuous monitoring and research ensure vaccine safety and ongoing
evaluation of any potential risks.

12. Community Immunity
Importance:
• Herd immunity is crucial in India for the
following reasons:
• Protects vulnerable individuals, including
those who cannot receive vaccines due to
medical conditions.
• Reduces the burden on healthcare facilities
during outbreaks.
• Aids in controlling and eventually eradicating
diseases like chickenpox and shingles.
Role of Widespread Vaccination:
• Widespread vaccination plays a pivotal role
in achieving herd immunity against
Varicella-Zoster Virus (VZV) in India.
• When a substantial proportion of the
population is vaccinated against VZV, it
disrupts the virus's transmission cycle.
• This is especially significant in a densely
populated country like India, as it prevents
widespread outbreaks and reduces the
impact on public health resources.

13. Vaccine Coverage Rates
and Implications in India