Cardiff and Vale University Health Board is offering the vaccine to individuals who have been in contact with a known case or have links to an affected setting.
Those who are not contacted directly do not require vaccination as part of the current outbreak response.
A spokesman for Cardiff and Vale University Health Board said: “Vaccination is an important way to help prevent hepatitis A from spreading.
“People identified as having had contact with a known case, or with an affected setting, will be contacted directly and offered vaccination where appropriate.
“Please take up the offer if you or your child are invited.
“If you are not contacted, you do not need to be vaccinated as part of the outbreak response and should not be concerned”.
However, if a parent or child becomes unwell or develops symptoms, they are being told to contact their GP or NHS 111 Wales for advice.
A spokesperson for the Health Board also emphasised that good hand hygiene also helps prevent the spread.
They explained: “Wash your hands thoroughly with soap and water after using the lavatory or changing nappies, and before preparing or eating food.
“These simple steps can help protect you, your family and your community”.
According to Public Health Wales, Hepatitis A is a viral infection that affects the liver and can be prevented with a vaccine.
It is primarily spread through contaminated food and poor hand hygiene, but can also be acquired through sexual contact.
Public Health Wales advises that good hand hygiene is key to preventing transmission.
This includes thorough hand washing with soap and water, especially after using the toilet, changing nappies, and before preparing or eating food.
Most people infected with hepatitis A recover fully without lasting liver damage, though the illness can be serious in rare cases.
Symptoms usually develop within several weeks to several months after exposure and may last up to six months.
These can include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, joint pain, jaundice, dark urine, pale stools, and itchy skin.
While there is no specific cure for hepatitis A, rest and supportive care can help manage symptoms.
Painkillers such as paracetamol or ibuprofen may be used, but dosing should be discussed with a GP to ensure it is safe for the liver.
Avoiding alcohol, wearing loose clothing, and staying in a cool environment can help ease symptoms.
The virus is most often contracted through close contact with an infected person, consuming food or drinks handled by an infected person, or eating shellfish from contaminated water.
Anyone diagnosed with hepatitis A is advised to stay off work or school for at least one week after symptoms such as jaundice begin.
They should also avoid preparing food for others and maintain frequent handwashing to protect those around them.
