The government said the latest two cases include a three-month-old from Wailali settlement in Wainadoi and a 17-month-old from Wailekutu in Lami.
The 18 cases are from the Serua/Namosi subdivision, Suva and Rewa areas.
The health ministry said two days into a mass vaccination campaign had seen over 45,000 people immunised in the central division.
Meanwhile, all sporting tournaments and events in Fiji have been called off due to the measles outbreak in the country.
Fiji's National Sports Commission said the postponement was due to advice from the health ministry against mass public gatherings.
The Commission said it was determined to put health and safety first.
A batch of 200,000 measles vaccines arrived in Fiji this week, prompting the second phase of the country's measles immunisation campaign.