Police have arrested two more people as an officer, who was stabbed in the stomach in Bow while undercover, remains in hospital.
Two 16-year-old boys handed themselves into an east London police station on Thursday.
They were arrested on suspicion of attempted murder and remain in custody.
The plain clothes policeman, aged in his 40s, suffered serious injuries after he was allegedly stabbed in the stomach by a gang while on a covert operation last Tuesday.
He was stabbed at least three times next to the Bow Bells pub in Bow Road at around 9.20pm.
His injuries are not believed to be life-threatening.
A 20-year-old man was arrested on Tuesday in Bedfordshire on suspicion of assisting an offender and has been bailed until mid-January.
Andrew Beadie, 20, of Claremont Road, Basildon, and Janine Morris, 24, of Rainhill Way, Bow, were both charged on Saturday with attempted murder and two counts of affray.
Morris was also charged with assisting an offender.
They both appeared in custody at Thames Magistrates' Court and were remanded in custody to appear at the Old Bailey on January 4.
A 17-year-old boy was arrested on the day of the incident on suspicion of attempted murder.
He remains on bail until a date in late January.
Detectives from the Homicide and Major Crime Command are investigating.
