#FreeShawkan campaign demands journalist's release
His latest court hearing - due to be held on Tuesday - has again been postponed.
Abu Zeid was detained on 14 August 2013 when covering violent clashes between supporters of the ousted president, Mohamed Morsi, and security forces. A French photographer and a US reporter were arrested alongside him.
Both were released, while Shawkan remains behind bars.
"Today's hearing has been postponed until August 3 because the authorities said they were unable to safely transfer the detainees to the court," said Ahmed Abu Seif, the journalist's lifelong friend and founder of the Free Shawkan campaign.
"To be honest we're not optimistic about the outcome of the trial, and we're expecting the worst. Mahmoud is the journalist that has been held the longest without being charged."
Abu Seif, based in Kuwait, said the jailed journalist required medical attention:
"Shawkan's health is failing - since he was arrested, he has not been allowed access to the Hepatitis C medicine he needs or been allowed to see a doctor."
Journalists and activists from around the world have taken to social media to support Shawkan. They have been condemning his imprisonment, and providing live updates on his hearing using the #FreeShawkan hashtag.
Some tweeps have been commenting on Shawkan's health condition - describing him as "seriously ill". Shawkan developed Hepatitis C in prison and his health is deteriorating badly, reports say.
A petition to "save" the photojournalist has collected more than 1,000 signatures.
The hashtag has been used at least 1,500 times in less than 24 hours, according to a Twitter analytics website.
His detention was extended for a further 45 days at a hearing on Wednesday 15 July.