Varicella vaccine

The varicella vaccine is a prescription medication belonging to the vaccine class.

The varicella vaccine is approved for active immunization against the varicella-zoster virus, prevents varicella (chickenpox), and reduces the severity of chickenpox infection in individuals, particularly children and adults.

It is not a part of national routine immunization programmes.

The varicella vaccine involves the absorption of the vaccine subcutaneously, distribution throughout the body, minimal metabolism, and primarily strengthening immunity by producing antibodies with insignificant excretion, enabling protection against the varicella-zoster virus.

The common side effects of the varicella vaccine include pain, swelling, redness at the injection site, low-grade fever and rash.

The varicella vaccine is available in the form of powder for injection.

Varicella vaccine is available in the United States, Canada, the United Kingdom, Australia, Germany, France, Japan, India, Brazil, and South Korea.

The varicella vaccine belonging to the vaccine class is a sterile powder for injection.

The varicella vaccination works by embedding a live but weakened strain of the varicella-zoster virus (VZV) inside the body. This vaccine activates by exposing you to a small amount of the virus or a viral protein, which prompts the body to produce immunity against the disease. The virus is weakened before being administered, activating the immune system without causing sickness. The immune system responds to the presence of the weakened virus by creating antibodies that are specifically directed against the varicella-zoster virus. Long-lasting defence is provided by these antibodies that remain in the body. These antibodies offer enduring protection because they stay in the body. The immune system can quickly identify and neutralize the virus if the wild-type VZV is exposed in the future, preventing or significantly reducing the risk of varicella (chickenpox).

The varicella vaccine is available as a powder for injection.

Powder for injection: To be administered parenterally, as applicable.

Varicella vaccine can be used as follows:

• For adults and kids at least 12 months old, the varicella virus vaccination is used to help prevent this illness.
• The vaccination protects people from chickenpox and helps to reduce the risk of severe consequences, especially in populations who are more vulnerable.

Varicella vaccine can help support the following health benefits:

• Prevention of chickenpox: The most effective method is the varicella vaccination. A doctor or nurse administers it, and it should not be administered to oneself. On the other hand, chickenpox is exceptionally infectious. Maintaining proper hygiene and routinely washing your hands can reduce the likelihood of chickenpox spreading and limit contact with those who have chickenpox. The vaccination significantly decreases the chance of developing the disease by immunizing people, especially children, against chickenpox.
• Prevention of shingles: Herpes zoster (shingles) can develop after the varicella-zoster virus, which also causes chickenpox, reactivates in a person's body. Nerve damage, severe rashes, and ongoing discomfort are all potential effects of shingles. Through broad chickenpox immunization, it is possible to indirectly minimize the incidence of shingles by lowering the transmission of the varicella-zoster virus. Even though the varicella vaccination is not intended to mainly prevent shingles, older persons, who are more vulnerable to this viral infection, benefit from its usage by having fewer cases of shingles. The varicella vaccination is particularly beneficial for senior citizens and raises their quality of life.
• Vulnerable populations: Life-threatening complications from chickenpox can occur, especially in high-risk populations, including newborns, expectant mothers, and those with weakened immune systems. These side effects can result in mortality, pneumonia, encephalitis, bacterial skin infections, and further complications. The varicella vaccination is very effective in lowering the risk of these adverse effects. The vaccination protects vulnerable groups' health by reducing chickenpox cases, which reduces its impact on healthcare systems.
• Herd immunity: Public health benefits greatly from extensive varicella vaccinations. The possibility of an outbreak of severe chickenpox ramifications among them is reduced. It protects the person vaccinated and those individuals with weaker immune systems, infants too young for vaccination, older people, or those with contraindications, reducing overall chickenpox transmission and minimizing the overall prevalence of chickenpox in the community. The varicella vaccine's administration ultimately results in a decrease in chickenpox-related morbidity and mortality.

Varicella vaccine is approved for its use in the following clinical indications:

• It is indicated for immunocompetent persons 50 and older who want to avoid getting shingles from the herpes zoster (shingles) virus.

• It is indicated for those 12 months of age and older who will receive an active immunization to prevent varicella.

Parenterally: The Varicella vaccine is given parenterally. In two doses, it is generally given as an injection subcutaneously or intramuscularly of the upper arm (deltoid region) or the anterolateral thigh.

When given concurrently with injectable vaccines, the shots have to be delivered using different syringes at different places. Following immunization, monitoring for at least 15 minutes for signs of acute allergic reactions is essential.

The dosage and duration of treatment should be as per the treating physician's clinical judgment.

Powder for injection: 1350 plaque-forming units/0.5mL

Dosage Adjustment for Adult Patients

Varicella Immunization

0.5 mL SC/IM in 2 doses series; repeat at least four weeks later.

The second dosage may be administered without resuming the schedule if the first dose was taken more than eight weeks ago.

The varicella vaccine is available in the form of powder for injection.

Varicella vaccine should be used to prevent chicken pox in children and individuals at high risk, along with no appropriate dietary restrictions.

Varicella vaccine usually has little effect on dietary or food substances when administered. Consuming regular foods and drinks before and after receiving the vaccine is safe.

Staying well hydrated by drinking water or other fluids is commonly advised. Maintaining a rich-balanced diet that includes a variety of fruits, vegetables and lean proteins can help boost the body's immunological response to the vaccine and overall health during vaccination.

The dietary restriction should be individualized as per patient requirements.

Varicella vaccine may be contraindicated in the following conditions-

• Hypersensitivity (to any of its components, including gelatin, neomycin, or both)
• Severe immunodeficiency due to any cause like HIV(CD4+ count <200 cells/mcL), leukaemia, chemotherapy, or malignant neoplasms affecting the bone marrow or lymphatic system.
• Pregnancy
• Fever (>101.3°F)
• Untreated active tuberculosis

The treating physician must closely monitor the patient and keep pharmacovigilance as follows.

• People with moderate or severe illness with or without fever should postpone being vaccinated until their condition improves.
• Children with weak immune systems, such as those with HIV/AIDS infection or cancer or who are taking certain drugs, may not respond as well to oral cholera vaccine and may consult a healthcare professional who might suggest modifying the vaccine schedule or giving additional doses to these people to improve protection.
• Avoid getting pregnant for three months after treatment.
• The vaccine is thermolabile and should be kept at -20°C or below.
• Syncope with brief visual abnormalities, weakness, or tonic-clonic movements has been reported with injectable vaccines.
• Up to five weeks after receiving the vaccine, stay away from high-risk individuals.
• Following vaccination, children with rheumatoid arthritis or other illnesses which require therapeutic aspirin should be thoroughly monitored.
• After receiving the varicella vaccine, individuals are advised to wait 14 days before receiving blood products unless the advantages of the blood product outweigh the requirement for immunization protection.

Unsafe to use during pregnancy.

There is no sufficient scientific evidence regarding the use and safety of the varicella vaccine in concurrent use with any particular food.

The adverse reactions related to the varicella vaccine can be categorized as

• Common: Pain, swelling, mild rash or redness at the injection site, mild fever, fatigue or fussiness in children.
• Less common: Moderate rash, high-grade fever >102°F [39°C]
• Rare: Serious allergic reactions (anaphylaxis) and seizures (febrile seizures).

Reports on Postmarketing

Body as a whole: Angioneurotic oedema, face oedema, and peripheral oedema are all symptoms of anaphylaxis (including anaphylactic shock).

Necrotizing retinitis (in immunocompromised people) is an eye disease.

Aplastic anaemia, thrombocytopenia (including ITP), and lymphatic system

Varicella (vaccine strain) is an infection and an infestation.

Encephalitis, cerebrovascular accident, transverse myelitis, Guillain-Barré syndrome, Bell palsy, ataxia, nonfebrile seizures, aseptic meningitis, dizziness, and paresthesia are neurological and psychiatric conditions.

Pneumonitis and pharyngitis are respiratory conditions.

Skin conditions include Stevens-Johnson syndrome, erythema multiforme, Henoch-Schönlein purpura, impetigo, cellulitis, and other secondary bacterial skin and soft tissue infections.

The clinically relevant drug interactions of the varicella vaccine are briefly summarized here:

• Immunosuppressants- The immunological response may be suppressed by immunosuppressive treatments such as radiation, antimetabolites, alkylating agents, cytotoxic medicines, and corticosteroids (used in dosages larger than therapeutic doses).
• Salicylates: For six weeks after immunization, prevent the use of salicylates (aspirin) or products containing salicylates in children and adolescents aged 12 months to 17 years due to the link between Reye syndrome and salicylate treatment and wild-type varicella infection.
• Immunoglobulins (IG): It is not recommended to administer this vaccination together with immunoglobulins (IG) or other blood products because they may include antibodies that prevent the vaccine virus from replicating, thereby decreasing an expected immunological response.
• Other Vaccines: Children are administered different vaccines to reduce any risk; it is generally recommended to administer them at separate sites and times from the varicella vaccine to minimize the risk of interference. Other live vaccines should be administered at least four weeks apart to avoid the risk of one immune response interfering with another.

The common side of the Varicella vaccine includes the following-

• Fever
• Rash that looks like chickenpox
• Swelling, discomfort, or redness where the injection was administered.
• Nausea, diarrhoea, and vomiting
• Pain in the stomach
• Loss of appetite
• Headache
• Fatigue

Varicella vaccine should be prudent in the following group of special populations.

• Pregnancy: Varicella vaccine is unsafe to use during pregnancy since there is clear evidence that it poses a risk to the developing baby.

Pregnancy Category: X; Avoid using when pregnant. The risks exceed any potential benefits. There are safer alternatives.

• Paediatrics: Varicella vaccine protects against chickenpox, lowering the possibility of severe disease, hospitalization, and complications. The vaccination is typically safe, and the most common side effects are minor and short-lived, reducing disease burden and healthcare expenses. It improves public health by avoiding varicella outbreaks and protecting the safety of children.

Dosage Adjustment for Paediatric Patients

Routine immunization

Minimum age: 12 months

a two-dose sequence SC/IM at 0.5 mL

First dose: 12 to 15 months

Second dose: 4-6 years; can be given earlier if at least three months have passed since the previous dose, but at least age 4.

Note: The second dose may be recognized as effective if it was given at least four weeks following the first dose.

Catch-up immunization for ages 7 to 18

7 to 12: 0.5 mL SC/IM twice, separated at least three months apart; if the second dosage was given at least four weeks following the first, it could be considered appropriate for children

More than 13 years of age: 0.5 mL SC/IM x 2 doses, separated by at least four weeks.

• Geriatrics: There is no sufficient scientific evidence traceable regarding the use and safety of the oral varicella vaccine for geriatric populations.

• Lactating mothers: There is no sufficient scientific evidence traceable regarding the use and safety of varicella vaccine for lactating mother populations.

Dosage Adjustment in Kidney Impairment

There are no specific dosage adjustments provided.

Dosage Adjustment in Hepatic Impairment

There are no specific dosage adjustments provided.

Overdosage of varicella vaccine rarely occurs because it is typically administered as a single according to the recommended schedule by healthcare professionals according to specific or precise dosing guidelines.

There is no specific antidote or treatment for excessive intake of varicella vaccine. Medical attention should be sought immediately when an overdose is suspected, followed by close monitoring for any adverse effects or allergic reactions. Supportive therapy should also be given, addressing any symptoms that persist or worsen. Physical treatment might be added if necessary.

Pharmacodynamics of varicella vaccine:

The varicella vaccine has a potential physiological mechanism that plays a role in its pharmacodynamics, involving its interaction with the immune system.

When administered, the live, attenuated virus in the vaccine stimulates the immune system. Mainly, immunoglobulin G (IgG), produced as a result, helps identify and neutralize the virus. When the immune system develops a rapid and effective defence against the varicella-zoster virus in the future, it is due to this memory activation that long-term immunity is established. Due to this strong immune response, which offers some protection against varicella, the vaccination is beneficial in avoiding chickenpox and its associated complications.

Pharmacokinetics of varicella vaccine:

Absorption: The live attenuated varicella-zoster virus (VZV) in the vaccination triggers an immunological reaction. The varicella vaccine is injected, and the vaccine's active ingredients enter the bloodstream.

Distribution: The attenuated virus particles travel throughout the body after entering the bloodstream. They reach immune system tissues like lymph nodes and initiate an immunological reaction.

Unlike drugs, varicella vaccines don't involve metabolism or elimination processes because vaccines contain inert viral proteins, not active drugs. The vaccine's effectiveness comes from the body's immune response and antibody production, which provides long-term defence against varicella infections and related diseases.

Onset: Seroconversion's onset lasts for 4-6 weeks.

Duration: Ten years after immunization, antibody titers were detected.

• Arbeter, A M. “Clinical trials of varicella vaccine in healthy adolescents and adults.” Infectious disease clinics of North America vol. 10,3 (1996): 609-15. doi:10.1016/s0891-5520(05)70316-0
• Ahern, Susan et al. “Clinical efficacy and effectiveness of alternative varicella vaccination strategies: An overview of reviews.” Reviews in medical virology vol. 33,1 (2023): e2407. doi:10.1002/rmv.2407
• Shapiro, Eugene D et al. “Effectiveness of 2 doses of varicella vaccine in children.” The Journal of Infectious Diseases vol. 203,3 (2011): 312-5. doi:10.1093/infdis/jiq052

• Inform the caregivers of the schedule for administering the varicella vaccine doses, emphasizing the benefits of vaccination, including reduced risk of contracting chickenpox and its complications.
• Inform the vaccination recipient, their parents, or their guardians whether they had any side effects from a prior dosage of the oral cholera vaccine, including regular check-ups and follow-up vaccinations as per the recommended schedule.
• Encouraging them to immediately report any unexpected or severe responses to the healthcare physician and, whenever applicable, to use reporting systems like the Vaccine Adverse Event Reporting System (VAERS)
• Inform caregivers of the recommended immunization schedule, which usually consists of two or three doses, depending on the vaccine brand. Also, mention the ages at which the doses should be administered and give the Vaccine Information Statements, which must be disclosed before immunization by the National Childhood Vaccine Injury Act of 1986 about the Centres for Disease Control and Prevention (CDC) website (www.cdc.gov/vaccines), these resources are freely accessible.

http://www.cdc.gov/vaccines/schedules/

https://www.cdc.gov/vaccines/vpd/varicella/public/index.html

https://www.indianpediatrics.net/oct2014/785 figure1.pdf

https://main.mohfw.gov.in/sites/default/files/Universal.pdf