What is drug resistance and why is it a problem?

Leading epidemiologists have warned that continued disruption to foreign aid funding, namely the sudden pause to the US President’s Emergency Plan for AIDS Relief (PEPFAR), could see a rise in the number of people who are resistant to HIV drugs.

PEPFAR provides a huge proportion of the funding for health systems in low middle-income countries, management of HIV.

However since the US stopped funding, programmes on the ground have been plunged into chaos, leaving patients without medication.

Now, epidemiologists and HIV experts have warned that if the disruption to funding continues, this could increase the number of people who become resistant to vital HIV medication.

What is drug resistance?

Drug resistance can develop when a virus or microbe mutates in a way that makes it less sensitive or resistant to a certain drug. This can lead to drug-resistant infections or viruses, which are harder, or impossible, to treat with the available medication.

Resistance to antibiotics, which has long been a concern globally, leads to almost five million deaths a year, according to the Wellcome Trust, with mortality rates high in low and middle-income countries.

Recent reports from the UKHSA have highlighted the growing problem of drug-resistant gonorrhoea strains, with experts warning it these strains could become untreatable.

Increased resistance can mean new treatments have to be developed to tackle a virus or infection.

What is HIV drug resistance, and why is it a concern?

Patients with HIV are prescribed antiretroviral therapy. HIV treatment aims to suppress the viral load of a person with HIV.

While there has been a major increase in the use of antiretroviral medicines, this has also been accompanied by the emergence of HIV drug resistance.

HIV drug resistance, according to the World Health Organisation (WHO), occurs when the genetic structure of HIV changes in a way that affects the ability of medicines to stop the replication of the virus.

The WHO warns: “All antiretroviral drugs, including those from newer drug classes, are at risk of becoming partially or fully inactive due to the emergence of drug-resistant virus. If not prevented, HIV drug resistance can jeopardise the efficacy of medicines used to treat HIV, resulting in increased numbers of HIV infections and HIV-associated morbidity and mortality.”

Speaking with The Independent, several experts explained this occurs when patients only partially take their medication. This is because the virus is present but due to the low adherence, it is able can replicate and account for the drug, making it less susceptible.

Resistance is less likely if a patient suddenly stops medication completely, but it is a risk if they are rationing drugs or not taking them as regularly as prescribed.

If a person maintains their treatment and maintains suppression of their viral load then drug-resistant HIV is less likely to emerge.

Drug resistance can also be found in some people before they begin treatment. The WHO says this type of resistance can either be transmitted at the time of infection or acquired during previous treatments.

The current first-choice medication used for HIV is Dolutegravir. Experts told The Independent this drug is vital as it is easy to take, allowing for better adherence, has a lower risk of resistance developing and is currently “cheaper”.

Previous first-line treatments were phased out largely due to increased resistance, according to Professor Andrew Phillips at UCL.

Currently, there are no alternatives to dolutegravir which are as effective, and so experts such as Professor Brooke Nichols warned that it is important resistance to this drug is limited as much as possible.

She explained that although HIV will always develop and eventually new treatments will be developed, currently there are no options which can match dolutegravir.

The concern is that the current pause on funding for HIV programmes continues in the long term, which could lead to patients not adhering to a regular schedule or rationing their treatment due to fears of shortages.

This piece is part of the Independent’s Rethinking Global Aid project