The impact of a flourish of the US president's pen in Washington a year ago continues to be felt on individual lives some 13,000km (8,000 miles) away in South Africa.

There was a collective gulp among some in the health sector here when, hours after he was inaugurated, President Donald Trump signed an executive order freezing US aid commitments.

For South Africa that meant the potential loss of an estimated $400m (£295m) that the US contributed each year to the country's HIV programmes – representing about a fifth of what it was spending on the issue.

Last year, the government provided $46m in response to the US decision - just 11.5% of what was lost.

The US also agreed a bridge plan of $115m that will last until the end of March in place of regular funding from the US President's Emergency Fund for Aids Relief (Pepfar).

Since being set up by President George W Bush in 2003, the US government has invested over $110bn in the global HIV-Aids response through Pepfar, saving 26 million lives, according to the state department.

Many of those lives were in South Africa as around 13% of the population are living with HIV, making it the country with the largest number of HIV-positive people in the world.

Enormous advances in treatment and prevention over the decades have ensured many are alive who would not be otherwise but these are expensive and the loss of funding could put many at risk.

Prof Linda-Gail Bekker, the head and co-founder of the Desmond Tutu Health Foundation and one of the world’s top HIV researchers, says there is no doubt there has been a reduction in testing and gaps in services.

Forty percent of her funding – around $8m - came from the US government.

This money was significant in carrying out a large number of what I call last-mile activities, she tells the BBC.

Among other services, the Tutu Foundation uses its money to fund mobile clinics for people unable or unwilling to go to government-funded ones.

On a bright summer day, a small group of women are sitting under a small awning outside one of their mobile clinics in Philippi, one of Cape Town's most dangerous townships.

They listen intently as a health worker from the foundation lists different types of preventative HIV medication. Those who have turned up do not want to add to the country's HIV statistics.

I want to take preventative medicine because anything can happen, says 28-year-old Esethu.

She’s here to get a second shot of Cabotegravir, commonly known as CAB-LA, an injectable form of pre-exposure prophylaxis (Prep) which reduces the chances of catching HIV by almost 80%.

She says the mobile clinics are very helpful because you don't have to walk that much to get to them or spend money on taxis.

However, health experts express concern that, without more funding, essential services could dwindle, leaving many vulnerable communities at risk.