Britain may be experiencing a "lucky break" as the rate at which swine flu is spreading slows, the Chief Medical Officer said.
A second wave of the pandemic was under way but current figures suggested the expected peak could be lower than was previously thought, Sir Liam Donaldson added.
An estimated 18,000 new cases were reported in England this week, up from 14,000 the previous week and 9,000 the week before that. But the rate of increase is nowhere near the weekly doubling experts had feared.
Sir Liam said: "It is proving so far to be a slow burner. It's possible it might peak at a lower and earlier level than expected which would be incredibly positive news." However, the H1N1 flu virus has killed two children in less than 48 hours in Northern Ireland.
A boy of 12, who had underlying health problems, died at Ulster Hospital, Belfast, on Wednesday, and a toddler under three died in the south-east of the province on Monday.