Public Health England (PHE) reported 415 new cases between 5 and 11 May, half the weekly figure from mid-April.
However, levels in 2014 remain the highest since 1980, and 8,322 cases have been reported since September 2013.
Officials are analysing samples from patients to determine why this season has seen such high levels of the infection.
As a seasonal disease, levels of scarlet fever usually decline at this point in the year, but PHE has warned against complacency.
Dr Theresa Lamagni, PHE’s head of streptococcal infection surveillance, said: 'It is still too early to be confident that the drop in the number of cases will be maintained as we are seeing fluctuating numbers each week and incidence remains high compared to recent years. We will continue to monitor the situation closely to see if there is a sustained fall over the coming months.
'We strongly urge people to remain vigilant and to go to their GP if they develop symptoms which suggest scarlet fever such as a sore throat, fever and rash.'