Liver patient Shahjahan's family feared the worst when a New Delhi public hospital told her to leave because her bed was needed in a coronavirus unit.

The 40-year-old mother had been on a ventilator with an acute infection for almost two weeks when she left Lok Nayak hospital on Tuesday night.

She died at her family home in Delhi the next morning. Other hospitals had turned her away because of the pandemic.

"The authorities just left her to die. Even when they referred us to another hospital, they refused to give us an ambulance," said Mohammad Khalid, a relative of Shahjahan.

The capacity of medical facilities around the world has been stretched by the surge of COVID-19 patients as outbreaks worsen in many countries.

It can cause people with other life-threatening diseases to miss out on vital care -- especially in places like India, where healthcare systems are shakier.

Dozens of people with serious medical conditions are camped outside India's national medical institute in tents set up by the Delhi government.

Many of them had travelled from other cities for now-cancelled appointments and can't go back due to transport restrictions under the nationwide lockdown that began on March 25.

Outpatient departments at the All India Institute of Medical Sciences (AIIMS) closed, forcing cancer patients and others with deadly ailments to take shelter in a grimy pedestrian subway and under canvas.

Though aid groups have provided some food and medicines, it had been 12 hours since Saryu Das had eaten when AFP met him.

- Subway death -

His son, who had mouth cancer, lay on a thin mattress with his face covered by a scarf. Flies hovered around him. Four days later, he died.

Waste littered the subway floor that is now home to more than 10 families unable to get back to their hometowns, with the mattresses so close that social distancing was impossible.

The AIIMS did not immediately respond to requests for comment on the death and the patients outside. But hospitals across the vast country of 1.3 billion people have been put on alert and its virus death toll is now above 280.

When Prime Minister Narendra Modi announced the lockdown, he gave millions of Indians taking life-saving drugs only four hours' notice.

Amulya Nidhi, a health activist based in Madhya Pradesh state, told AFP the government knew that vulnerable patients -– including those with silicosis and tuberculosis, which kills tens of thousands each year in India, as well as pregnant women -- were at risk.

"I'm getting distress calls from across India over access to basic medicines and treatment," said Nidhi.

- Shut out -

"It is important to expand healthcare facilities to fight COVID-19. At the same time, hospitals and ambulances have to be available for patients with other problems," he said.

In February, 39-year-old Maitri Lakra was found to be in the initial stages of tongue cancer. Being HIV-positive only added to her woes.

Doctors at AIIMS referred her to their campus in Haryana state for pre-surgery tests, which started mid-March. But 10 days later, she was told that all radiology appointments were postponed.

As her condition deteriorated -– bleeding from the tongue and in unbearable pain -– she filed a petition with the Delhi High Court and has finally been admitted to AIIMS.

"Her cancer is at stage three now. Had she received treatment on time, this would not have happened," her son Debashish Dag said.

Vinay Shetty, from the Mumbai-based Think Foundation that works with people with the blood disease thalassaemia and organises blood donation camps, said those needing transfusions are among the most vulnerable.

"Those needing drugs may not have a problem, but anybody needing blood will," Shetty said, adding the government had to encourage blood donors.

Public health expert Anant Bhan said India's focus on COVID-19 could lead to other diseases such as tuberculosis spreading.

"Family members in lockdown with tuberculosis patients are at risk. After the lockdown is removed and people start social interactions, it could spread the infection the same way COVID-19 patients could spread infection," Bhan said.

"Deaths because of COVID-19 and not directly of it is something that we need to worry about. We need to ensure those who need essential services have it," he said.

And time is already running out for Shahjahan's fellow patients in the subway and tents outside AIIMS.

"The doctors told me they could not do my chemotherapy session now and that they'll call me when the lockdown is lifted. That call may take weeks," said 25-year old Rampur resident Mohammed Shan-e-Alam.

"Now I can't go home and I can't go to the hospital."