There is a "downward trend" in the number of people suffering from the winter vomiting bug, health officials said.
The number of confirmed cases of norovirus in England and Wales has lowered in recent weeks, with the latest data showing that there was a 32% decrease in the number of cases during the first week of 2013 compared with the last week of 2012, the Health Protection Agency (HPA) said.
But the experts warned the figure could rise again because of the unpredictability of the norovirus season.
Even though there has been a decline in cases, the number of people who have contracted the bug this season is still 56% higher than it was last year.
The HPA said there had been 4,407 laboratory-confirmed cases of norovirus so far this season. But for every reported case an estimated 288 are not reported, meaning as many as 1.26 million people could have suffered from the bug.
Experts said there had been 728 outbreaks in hospitals so far this season.
The HPA recently revealed that a new strain of norovirus has been responsible for the majority of recent cases.
The new variant of the bug, called Sydney 2012, has become the "dominant strain" and will have caused many of the cases of the recent outbreak.
In October, when the number of cases started to increase, the HPA performed genetic testing of norovirus strains in England and Wales.
They found a "cocktail of different strains" that were circulating around the population. But recent analysis has shown that Sydney 2012 – which does not cause more serious illness than other strains – has overtaken all others to become the dominant strain.
John Harris, an expert in norovirus from the HPA, said: "Norovirus activity always varies from year to year and although we might have expected cases to rise again now we have passed the new year period this hasn't been the case.
"We can't read anything into this fall and don't know how busy the rest of the season will be. The busiest months are normally from December to April, so further cases will occur but we can't say if there will be further significant increases in the number of laboratory reports."
Norovirus is highly contagious and can be transmitted through contact with an infected person or contaminated surfaces and objects.
It is known to spread rapidly in closed environments such as hospitals, schools and nursing homes.
Symptoms include sudden vomiting, diarrhoea, a temperature, headache and stomach cramps. The bug usually goes away within a few days.
The HPA has urged anyone with symptoms to avoid attending hospital or care homes to avoid spreading the illness to people suffering from underlying health problems.