Official figures published on 3 October revealed new HIV diagnoses among gay and bisexual men had dropped from 3,570 in 2015 to 2,810 in 2016. The decline was particularly steep among those living in London, who saw a 29% fall in diagnoses during this time period.
PHE attributed the fall in new cases to regular and frequent testing, as well as prompt diagnosis and treatment.
The decrease in HIV diagnoses in gay and bisexual men coincides with effective treatment becoming widely available.
People living with HIV can take antiretroviral drugs (ARVs) daily to keep the virus at bay, giving them the chance to live a relatively normal life.
The drugs work by blocking the enzymes that HIV uses to infect immune cells. This stops the virus from multiplying further and brings HIV levels in the blood down to almost zero.
Additionally, people at high risk of contracting the virus can take a course of preventative drugs called PrEP. According to the Centers for Disease Control and Prevention, taking PrEP daily reduces the risk of contracting HIV from sex by more than 90% and by more than 70% for those who inject drugs.
PrEP has been a contributing factor in the downturn in new diagnoses in gay and bisexual men, PHE said. As such, it is supporting NHS England in a three year PrEP Impact Trial beginning in October 2017.
While the trials continue, PrEP is available privately from some clinics.