A pupil at a second Charedi school in Stamford Hill has tested positive for coronavirus over the past week.
Hackney Council said a pupil at the state-aided Yesodey Hatorah Senior Girls School was found to have contracted the disease at the weekend.
The "bubble" of eight girls of which she was part was now staying at home for two weeks, the council said.
The state-aided Lubavitch boys and girls primary schools in Stamford Hill were closed on Monday and Tuesday after a girl tested positive for the virus.
They reopened on Wednesday following "a deep clean", Hackney said.
In April, Yesodey Hatorah lost its longstanding principal, Rabbi Avrohom Pinter, from the virus.