Health officials warn anyone who went to these two Auckland locations is now at grave risk of catching the life-threatening measles virus.
Already, two people have been struck down by the highly-infectious disease - including one infant.
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Auckland Regional Public Health Service (ARPHS) fears that they might have spread it to others at these two public events - potentially putting hundreds at risk.
In Canterbury there are now currently 27 confirmed cases, with a further 20 suspected cases being checked.
The adult was at an event at the Life Central Church in Normanby Rd on the evening of Wednesday, March 6.
The infant was at the International Women's Day event at the Wesley market on the morning of Friday, March 8.
ARPHS says anyone at these locations at these times may come into contact with the airborne virus.
They need to watch for symptoms - a high fever, runny nose, cough and sore red eyes, followed by a rash starting around the head and spreading to the body.
The disease can lead to complications such as ear infections, pneumonia, seizures, diarrhoea and encephalitis (swelling of the brain).
The Ministry of Health says up to 30 percent of people with measles will develop complications - usually children under five and adults over the age of 20.
"If you feel unwell, please call your medical practice first and tell them if you have these symptoms, or you may have been exposed to the illness. You could infect others in the waiting room if you just turn up," Dr William Rainger says.
"Measles is one of the most contagious airborne diseases, and is infectious before the rash appears. It is very easily transmitted from one person to another, possibly by being the same space where an infected person has been."
The best protection against measles is immunisation, health officials say. Two doses are needed of the measles, mumps and rubella vaccine to be fully immune.
Many young people in the Auckland region are not fully immunised, and ARPHS is urging people to get up to date.