Anxious people fearing they have caught Covid-19 have been contacting the Singapore Civil Defence Force (SCDF), pleading for help and demanding ambulances, despite having mild symptoms.

One recent caller complained about having a cough that had persisted for two days after a visit to the doctor.

Operations centre specialist Sergeant Muhammad Aminurashid Ya'acob soon identified it as one of the many non-emergency calls the SCDF receives daily and persuaded the caller to go to a general practitioner or polyclinic.

"We've had to reassure callers more now... We take a longer time for each call, and we have to reassure them to make sure they don't jump to conclusions," said Sgt Aminurashid.

The SCDF Operations Centre has had to adapt quickly to the challenges posed by the fast-evolving coronavirus crisis.

As of Saturday, its paramedics have sent 4,205 suspected Covid-19 cases to hospitals, of which only 57 were confirmed to be infected.

The SCDF responded to 64,695 emergency medical calls in the four months to April 30, up 4 per cent compared with the same period last year.

A team of around 25 officers is on duty at any point in the day, responding to around 800 calls in a 24-hour period.

Operators try to identify suspect Covid-19 cases by asking basic triage questions, which change as the situation continues evolving.

Warrant Officer (WO) Hazlina Ja'afar, an emergency medical services operations specialist, said SCDF constantly checks with the Health Ministry to align its questions with the ministry's recommendations.

In January, for example, they focused on identifying people with a travel history to China. Now, they consider a host of additional factors, such as whether the patient has had contact with other positive cases or if their job puts them at risk, she said.

WO Hazlina also has to monitor the health of paramedics who attend to confirmed cases, although none have caught the virus, largely due to their diligent use of protective equipment.

The whole situation is highly dynamic. She said: "This means we are constantly on edge during the whole shift."

WO Derrick Neo, a senior operations centre specialist, said Covid-19 cases in non-critical condition are transported in non-emergency ambulances or via taxis or Grab cars whose drivers are trained in safety protocol.

But it can be difficult to persuade distressed callers, noted Sgt Aminurashid. "We have to follow protocol and ask them specific questions, but that can sometimes agitate them."

Some are "very paranoid" and will call for an ambulance, even though they display only mild symptoms like a cough, he added.

"We tell them that it doesn't meet our criteria, but they'll keep telling us that they are so afraid. We have to slowly convince them to see a GP or go to a polyclinic."

However, Sgt Aminurashid has also attended to critical cases, such as dispatching paramedics to people on stay-home notices who suddenly had difficulty breathing.

Despite the new challenges, operators said it is all part and parcel of their job in the operations centre.

WO Neo added: "Ops centre has always been exciting. We're always meeting interesting callers or have interesting incidents to respond to."