The heartrending photograph of a Syrian baby who lost his eye in an airstrike has set off a viral social media campaign, with users sharing pictures of themselves covering one eye.

The shot depicts 40-day-old Karim Abdallah, wrapped in a puffy red jacket, with crescent-shaped scarring where his left eye should be and a dark red welt on his forehead.

An October 29th government airstrike on an opposition bastion near Damascus severely wounded Karim and killed his mother, according to relatives and the doctor who treated him -- and kicked off a worldwide support campaign.

Users are taking pictures of themselves covering one of their eyes and sharing them on Twitter and Facebook with the hashtag #SolidarityWithKarim.

The campaign even reached the UN, where British ambassador Matthew Rycroft tweeted a photograph of himself at the Security Council, his right hand over his eye.

"When we sit around the UNSC & warn that inaction will mean more people are going to die. More schools bombed. More children scarred. This is what we mean," he wrote.

"We must see an end to the bombardment & siege of Eastern Ghouta."

Government forces have besieged the opposition-held Eastern Ghouta region since 2013, restricting access to food and medicines for some 400,000 residents.

Photographs in solidarity with Karim have been posted by other Syrian children, journalists, activists and members of the White Helmets rescue service, which operates in opposition-controlled areas.

The campaign was launched by Amer Almohibany, a freelance photographer in Eastern Ghouta and occasional AFP contributor.

"I visited the baby, and he made his mark on me even before taking his picture. It haunted me," said Almohibany, 28.

"The goal of the campaign is to... bring to the world the voice of this baby, who lost his eye and his mother," he said.

The raid that wounded Karim hit a market in Hammouria, a town in Eastern Ghouta, on October 29th.

Eastern Ghouta is one of four "de-escalation" zones agreed in May in a bid to reduce fighting in some parts of the war-ravaged country.

More than 340,000 people have been killed and half the country's population displaced since the conflict broke out in 2011.

Over the years, several Syrian children have become powerful symbols of the civilian suffering brought on by the war, including toddler Omran, who was photographed bloodied in an ambulance in second city Aleppo in 2016.