Story highlights The last known pediatrician left in rebel-held Aleppo was killed in an airstrike recently

Actor Javier Bardem says world leaders must show backbone in protecting healthcare workers in warzones

(CNN) Editor's note: Javier Bardem is an Oscar-winning actor who is collaborating with MSF and Medics Under Fire, a new organization that aims to reinstate protections for medical workers in conflict zones. The views expressed in this commentary are solely those of the writer.

The grainy, stuttering CCTV images are haunting. Dr Mohammed Maaz, the last pediatrician working in the besieged Syrian city of Aleppo, diligently going about his work, in the face of unimaginable pressure. The footage is then engulfed by a cloud of dust and debris, as the Al Quds hospital is hit by an airstrike. At least 50 died, 60 more were injured. Dr Maaz perished along with his colleagues and patients.

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Dr. Maaz was the last known pediatrician left in rebel-held Aleppo. The children of that city are now left more vulnerable than ever before. It is lamentable that in Syria, the World Health Organisation reports that 57% of public hospitals and 51% of public health clinics have been closed. There are now only 25 doctors left in Aleppo, where once there were 5,000.

Since the beginning of the conflict in Syria, Dr Maaz endured horrors most of us cannot even imagine. Yet his job was to treat injured and dying children and he continued to do so despite the risks. All the while his colleagues in the medical profession around him fell to the indiscriminate nature of this war, where hospitals, medical professionals and patients are as much targets as armed soldiers.

Photos: Aleppo photographer watches city die Two children walk past a "White Helmet" soon after an airstrike hits the Shaar neighborhood of Aleppo. Hide Caption 1 of 10 Photos: Aleppo photographer watches city die Members of the "White Helmets" civil defense volunteers carry the body of a man killed in a Russian airstrike in Andan town in the countryside north of of Aleppo. Hide Caption 2 of 10 Photos: Aleppo photographer watches city die Buses piled one on top of the other offer some protection from enemy fire. Hide Caption 3 of 10 Photos: Aleppo photographer watches city die Keeping the lights on: The electricity "operations room" in a neighborhood of rebel-held Aleppo. Hide Caption 4 of 10 Photos: Aleppo photographer watches city die Two men and their donkey navigate the bombed alleyways of Almarja district in eastern Aleppo. Hide Caption 5 of 10 Photos: Aleppo photographer watches city die A mother watches over her children as they return from school; the massive sheet hanging in the street is to deter government snipers. Hide Caption 6 of 10 Photos: Aleppo photographer watches city die A street that is monitored by regime snipers. Hide Caption 7 of 10 Photos: Aleppo photographer watches city die A stall holder waits for customers; there are reports of some hoarding of rice and flour as the regime's siege tightens. Hide Caption 8 of 10 Photos: Aleppo photographer watches city die A street market in Aleppo that is still open despite constant airstrikes -- and the huge slab of concrete hanging over it. Hide Caption 9 of 10 Photos: Aleppo photographer watches city die There is still fresh produce in the market stalls but it is more difficult to bring into the city, and much more expensive than even a few weeks ago. Hide Caption 10 of 10

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