SINGAPORE - Regeneron Pharmaceutical's Covid-19 antibody cocktail - which can be used to treat patients who are mildly sick but are at risk of severe illness - will likely be used in Singapore once it is available, said the National Centre for Infectious Diseases (NCID).

This follows results from a large British study published on June 16 that the drug can reduce the mortality rate by 20 per cent among people who have been hospitalised for Covid-19 and whose immune system had not mounted an antibody response.

This translates to six fewer death for every 100 people who are seronegative, meaning they had not mounted an antibody response , the study noted.

Dr Shawn Vasoo, clinical director of NCID, told The Straits Times that besides these findings, previous data on the Regeneron antibody has indicated that patients who are at risk of progressing to severe Covid-19 disease, and were treated as outpatients with the drug had a lower number of visits to the hospital (2.8 per cent) than those who were not given the drug (6.5 per cent).

"Together, this data is supportive that Regeneron's antibody has a role in select patients with Covid-19 who have milder illness but are at risk of progression of disease, and those who may not have mounted an antibody response.

"We look forward to the full data being published," said Dr Vasoo.

The drug has been included in the NCID's treatment guidelines, which was updated on June 14, saying it can be considered for high-risk patients who have developed symptoms within 10 days.

This includes patients who are above the age of 65 years old, have chronic kidney disease, diabetes, or are currently receiving immunosuppressive treatment.

Eligible patients will likely be given the treatment as part of a monitored clinical programme once it is available in Singapore, Dr Vasoo said.

Singapore had also contributed to the development of the antibody cocktail, using three Covid-19 patient samples as a starting point, said Associate Professor David Lye, director of the Infectious Disease Research and Training Office at the NCID.

The antibody cocktail was used to treat then US President Donald Trump after he tested positive for Covid-19 in October last year.

Known as REGN-COV2, the treatment is a combination or "cocktail" of two antibodies. A cocktail would make it more difficult for the virus to mutate and escape the antibodies as more of them are targeting different sites of the virus.

When asked if Regeneron will be applying for interim authorisation with the Health Sciences Authority for local use, its collaborator from Roche said that it is working with global regulatory bodies to bring the antibody cocktail to as many people as possible if it is approved.

HSA had on June 30 granted interim authorisation for GlaxoSmithKline Singapore (GSK) and Vir Biotechnology's drug, sotrovimab, for patients who are at risk of developing severe Covid-19.

The Ministry of Health had said that the drug will likely be available by September if there are no unforeseen delays in delivery.

NCID said in its guidelines that both sotrovimab and the Regeneron antibody cocktail may be considered for treatment in patients with mild-to-moderate Covid-19 disease, and are at high risk of progressing to severe Covid-19 disease.

However, it noted that the benefit of monoclonal antibodies - which are laboratory-made proteins that mimic natural antibodies produced by the body to fight off infection - may be linked to worsened disease when given to patients who require high-flow oxygen or mechanical ventilation.

To treat patients with more severe forms of Covid-19 disease, NCID has also included the use of remdesivir, steroids such as dexamethasone, tocilizumab and baricitinib in its treatment guidelines.

Prof Lye said that remdesivir, an antiviral, is used on patients who need low amounts of oxygen support, whereas dexamethasone is for patients who require higher amounts of oxygen support or a machine to aid with their breathing.

For patients who are not suitable for dexamethasone, due to reasons such as poorly controlled diabetes or osteoporosis (a type of bone disease), then baricitinib can be considered, noted Prof Lye.

Baricitinib, a drug that reduces the activity of the immune system, has been used to treat patients with rheumatoid arthritis.

On the other hand, patients who do not show any improvement after being given dexamethasone, or who continue to show inflammation in the body will be given tocilizumab, added Prof Lye.

Tocilizumab is a monoclonal antibody which is able to blunt a hyperinflammatory response in the body, especially among those with severe Covid-19.

To further expand Singapore's arsenal of Covid-19 therapeutics, NCID is running a clinical trial with the National Institutes of Health in the US, known as the ACTIV-3/TICO trial, focusing on two types of novel drugs.

ACTIV-3 is part of a public-private partnership to develop a coordinated research strategy for prioritising and speeding development of the most promising treatments and vaccines.

These drugs include:

- A long-acting antibody by Astrazeneca, known as the AZD7442 drug, which was derived from two patients who had recovered from Covid-19.

- A small-molecule drug known as Ensovibep, designed by Molecular Partners in partnership with Novartis. The drug is designed such that it is able to bind to three different locations on the spike protein of the Sars-CoV-2 virus, so as to prevent it from infecting human cells.