The dominant COVID-19 strains that tore through the country during the winter wave now account for less than a quarter of new cases in New South Wales.

The weekly respiratory surveillance report issued by NSW Health showed three-quarters of new coronavirus cases are not of the BA.4 and BA.5 strains.

These variants are either the same or very similar to mutations that were in wide circulation at the start of the year.

COVID-19 cases are up 9.1 per cent in NSW this week, with 37,088 people diagnosed.

But the seven-day rolling average of hospital admissions has declined slightly.

This week there was an average of 100 people admitted to hospital with COVID-19 each day, down from 103 last week.

But emergency department presentations related to coronaviruses have increased from 321 to 374.

Thirty-five COVID-19 deaths were reported this week. Four of those were under 65-years-old.

NSW Health warned there was some "low-level influenza activity". Flu shots and COVID vaccines remain recommended, especially for those heading to the northern hemisphere.