Varicella vaccine (VNS)
This is an investigational vaccine designed to protect against chickenpox (varicella). It is being tested for intramuscular administration, which means it is injected into a muscle.

Varivax (VV)
This is an approved vaccine that protects against chickenpox. It is administered subcutaneously, which means it is injected under the skin.

Priorix (MMR vaccine)
This is a combination vaccine that protects against three different diseases: measles, mumps, and rubella. In this trial, it is being tested for both intramuscular and subcutaneous administration.

Varicella – A highly contagious viral infection caused by the varicella-zoster virus that primarily affects children. The disease typically begins with a fever and general feeling of unwellness, followed by the appearance of a characteristic itchy rash. The rash progresses from small red bumps to fluid-filled blisters that eventually crust over. The condition usually spreads across the entire body in waves, with new spots appearing while others are healing. Symptoms typically last between 5-10 days, during which time the virus is most contagious.

Measles – A viral infection that begins with cold-like symptoms including fever, runny nose, and cough. A distinctive red-brown rash appears a few days later, typically starting on the face and spreading downward across the body. The infection also causes characteristic white spots inside the mouth called Koplik’s spots. The disease is highly contagious and can spread through airborne particles.

Mumps – A viral infection that primarily affects the salivary glands, causing them to become swollen and tender. The most noticeable symptom is swelling of the parotid glands, which causes the cheeks to puff out. Initial symptoms include fever, headache, muscle aches, and fatigue. The swelling typically appears first on one side before affecting both sides of the face.

Rubella – A viral infection characterized by a distinctive red rash that first appears on the face before spreading to the rest of the body. The condition often begins with mild fever and swollen lymph nodes, particularly behind the ears. The rash typically lasts about three days and may be accompanied by mild joint pain and cold-like symptoms.