(CNN) New HIV diagnoses in the United Kingdom have fallen by almost a third since 2015, bringing the island nation closer to its goal of zero new HIV transmissions by 2030.

They fell from 6,271 in 2015 to 4,484 in 2018 -- a decrease of 28% and the lowest level since 2000, according to data released by Public Health England (PHE) on Tuesday.

The decline comes after a nationwide campaign for HIV prevention, which included more HIV testing, condom provision and the use of HIV prevention treatments like pre-exposure prophylaxis (PrEP) and antiretroviral treatment (ART).

PrEP involves the use of daily pills -- usually antiretroviral drugs -- to reduce the risk of contracting HIV through sex. The treatment is up to 90% effective, according to the US Centers for Disease Control and Prevention.

ART is just as promising -- a 2019 study of almost 1,000 gay male couples with one HIV-positive partner who took the treatment found no new cases of transmission to the HIV-negative partner during sex without a condom.

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