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 $400 million (£295 million) 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 $46 million in response to the US decision - just 11.5% of what was lost.

The US also agreed a bridge plan of $115 million 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 $110 billion 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, stresses that the reduction in funding has resulted in decreased testing and gaps in service provision.

Among other services, the Tutu Foundation uses its money to fund mobile clinics for people unable or unwilling to go to government facilities. They continue to operate even as other charities have had to shut down.

On a bright summer day, women gather outside one such mobile clinic in Philippi, a township in Cape Town known for its challenges. They rely on these clinics for access to vital HIV preventative treatments.

Health Minister Dr. Aaron Motsoaledi is hopeful for additional HIV funding in the next budget while working with other donors to fill the gap left by the US. However, the battle against HIV in South Africa remains precarious without significant financial support.