There's been a dramatic drop in HIV infections in NSW which health authorities attribute to the extended lockdown during the height of the COVID-19 pandemic.

From January to September, 141 NSW residents were diagnosed with HIV, a decrease of 31 per cent compared to the average for the last five years.

NSW Chief Health Officer Kerry Chant said the decline was likely driven by the effects of the COVID-19 pandemic and restricted movement, as people remained at home.

However, testing rates were down from last year.

"As we start to open up, it is essential that at risk people get tested now," Dr Chant said on Wednesday.

"With the on-going risk of COVID-19, ensuring people living with HIV are diagnosed and begin treatment is critical to positive health outcomes."

Early testing and diagnosis was linked to treatment, prevented transmission and enabled people living with HIV to enjoy a long and healthy life, she said.

There are now online and home-based testing options and self-test kits would be available in pharmacies soon, Dr Chant said.

The NSW HIV Strategy 2021-2025 aims to achieve a 90 per cent reduction in the rate of preventable HIV infection to achieve the virtual elimination of HIV transmission in NSW.

In 2021-22 the NSW government is investing $23.7 million in services to strengthen HIV testing, treatment, and prevention.