Infectious Disease Physician Dr Asok Kurup talks about oral antivirals for treating COVID-19 and how they can benefit populations who are at higher risk of severe infection.

The efficacy of vaccines in the prevention of COVID-19 has been well-established since the first Cominarty® vaccine was rolled out in December 2020.

Since then, other types of treatments have also emerged in the market specifically designed to treat COVID-19 or reduce its severity, such as oral antivirals (OAVs) such as nirmatrelvir and ritonavir. Dr Asok Kurup, Infectious Disease Physician from Infectious Diseases Care, Mount Elizabeth Hospital, shares how oral antivirals are especially beneficial to populations who are at a high risk of severe COVID-19.

Nirmatrelvir blocks a crucial enzyme needed by the COVID virus, SARS-CoV-2 to duplicate itself,  prohibiting the virus from replicating itself, and reducing the spread of the virus in the body, while, ritonavir blocks an enzyme responsible for nirmatrelvir’s breakdown in the liver, prolonging its presence in the body and boosting its activity.

Who are the at-risk populations?

Individuals who are at risk of poorer clinical outcomes in the event of a COVID-19 infection include:

  1. Persons aged 60 and above, while persons aged between 50 to 60 years old are also considered to be at higher risk of developing severe disease from COVID-19 infection, relative to younger age groups.
  2. Immuno-compromised people, or those with concurrent medical conditions such as obesity (e.g., adults with a body mass index (BMI) of 30 or more), hypertension, diabetes, chronic heart and lung diseases, kidney diseases on dialysis, hypercoagulable states, cancer, or patients on drugs that cause immunosuppression.
  3. Pregnant women
  4. Persons with Down syndrome
Dr Asok Kurup, Infectious Disease Physician from Infectious Diseases Care, Mount Elizabeth Hospital

Dr Asok Kurup, Infectious Disease Physician from Infectious Diseases Care, Mount Elizabeth Hospital

Since January 2023, Singaporeans aged 60 years and above make up the majority of COVID-19 deaths by month as well as weekly hospitalisation rates in the intensive care unit (ICU), and this is mainly associated with frailness based on old-age syndromes and lowered bodily functions. Persons with Down Syndrome tend to experience accelerated ageing that affects most of the function of their organs, increasing their risk of severe COVID-19.

In obese people, excess body fat can overpower the normal working mechanism in their lungs, resulting in their reduced capacity to retain air. Pregnant women, especially in the later stages of pregnancy, may also suffer from reduced functional capacity of the lungs and altered immunity.

“The most widespread reason among all high-risk individuals for severe COVID-19 is related to the lowered function of organs, particularly the immune and respiratory systems. In people with stacked or multiple comorbidities, their organs’ functions and general health are already compromised. Thus, when these patients are infected with the novel coronavirus, they are more prone to lung damage and inflammation, putting their lives at greater risk compared to individuals without comorbidities,” explains Dr Asok.

“Patients infected with SARS-CoV-2 while undergoing cancer therapy will also not be able to fight off the infection. Cancer treatments may produce a reduced antibody response after vaccination. Lymphoma tumours can also form in the lymphatic system and affect the functions of the immune system, leading to inadequate immune response to viral infections like COVID-19,” adds Dr Asok.

How do doctors prescribe oral antivirals to patients?

“When patients display symptoms such as chills, fever, cough, and body aches and test positive for COVID-19 with the Antigen Rapid Test (ART) and a DNA detection test known as the Polymerase Chain Reaction (PCR) test, we can now prescribe them with OAVs. Patients who fall within the high-risk groups and are at risk for severe COVID-19 are priorities when it comes to OAVs,” says Dr Asok.

“For patients who are on many different medications, including immuno-suppressive medications or steroids, we usually check for contraindications that the OAV might have with these medications before prescribing them with the OAV,” explains Dr Asok.

Still important to stay vigilant

Although contracting COVID-19 is no longer the death sentence it once was when it first emerged, the possibility of new emerging variants is still present.

Dr Asok urges individuals who fall into the high-risk category for severe COVID-19, or have a family member in a high-risk category, to test early even if symptoms are mild and if they have been previously vaccinated.

“If you are positive for COVID-19, seek treatment quickly at the nearest OAV clinic which can be found on Look for clinics with letters OAV next to their name as this indicates they stock oral antivirals. Patients who are prescribed OAVs within five days after symptoms show, have shown much better outcomes than those who wait after five days of symptoms,” he says.

“Meanwhile, if you belong to the high-risk group, continue to mask up especially in confined places or on public transport, and maintain good hand hygiene. If you live with or care for high-risk individuals, ensure you are up to date with vaccinations and have at least one booster shot. We have also been seeing a rise in other respiratory-related viruses such as influenza and rhinovirus infections, so getting a flu vaccine is also recommended.”


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