The scavengers wait patiently for a dump truck to tip the rubbish on the summit of the landfill outside India’s capital New Delhi. Armed with plastic bags, they plunge their bare hands into the rubbish and start sorting it.

Every day, more than 2,300 tonnes of waste is dumped at the landfill at Bhalswa that covers an area bigger than 50 football fields, with a pile taller than a 17-storey building. And every day, thousands of these informal workers climb the precarious slopes to pick through what can be salvaged.

They are among the estimated 20 million people around the world who are pivotal in keeping cities clean, alongside paid sanitation employees. But unlike those municipal workers, they usually are not eligible for the coronavirus vaccine and are finding it hard to get the shots.

The pandemic has amplified the risks that these informal workers face. Few have their own protective gear or even clean water to wash their hands, said Chitra Mukherjee of Chintan, a non-profit environmental research group in New Delhi.

“If they are not vaccinated, then the cities will suffer,” Mukherjee said.

Manuwara Begun, 46, lives in a cardboard hut behind a five-star hotel in the heart of New Delhi and feels the inequity keenly. Chintan estimates that each year, those like her save the local government more than $50m and eliminate more than 900,000 tonnes of carbon dioxide by diverting waste away from landfills.

Still, they are they not considered “essential workers” and thus are ineligible for vaccinations.

Begun has started an online petition pleading for vaccines and asking, “Are we not human?”

Sanitation workers employed by local governments in South Africa and Zimbabwe are likely to be in line for the COVID-19 vaccine after health workers, unlike those who sort through the rubbish.

At the Dandora landfill in Kenya’s capital of Nairobi, some of the scavengers who are not eligible for a shot don medical gear discarded by hospitals and health clinics, saying it especially protects them from the weather during the rainy season.

There is no doubt that these people provide an essential service, says Louise Guibrunet, a researcher at the National Autonomous University of Mexico who has studied the issue.

In Mexico, scavengers help municipal workers on rubbish trucks and often collect waste from neighbourhoods not served by the authorities. The work is dangerous, and injuries are common, so governments have an incentive to not recognise them or provide benefits like healthcare, she said.

They often are already poor, moving to unfamiliar cities to eke out a living by sorting garbage, says Robin Jeffrey, a professor at the Institute of South Asian Studies at the National University of Singapore. That many of these workers in India belong to poor Muslim or Dalit communities adds another layer of prejudice. Dalits once were known as “untouchables” are at the bottom of the country’s hierarchical caste system.

“The vaccine is just another, and very dramatic, example of an exclusion that has prevailed before COVID-19 came on the horizon,” said Jeffrey, who co-authored a book on waste in India in 2018.

India said it will give vaccines to everyone more than 45 of age starting on April 1. At private hospitals, each shot is sold for 250 rupees ($3.45), but they are free at government hospitals.