Mr Hancock made the announcement on Twitter on Thursday, July 30 at around 9pm.
Laws placing restrictions on people who live in Manchester, parts of east Lancashire and West Yorkshire were published on Tuesday, August 4 and came into force from midnight today – Wednesday, August 5.
They ban people from different households meeting in their homes, gardens or other private residences.
People are also barred from meeting those from different households in areas outside the lockdown zone, such as at homes in nearby towns not subject to the rules.
Meeting in groups of more than 30 in public places is also prohibited.
The rules apply in the following places – but the ‘lockdown zone’ could be changed by the Health Secretary at any time: Bolton, Bury, Manchester, Oldham, Rochdale, Salford, Stockport, Tameside, Trafford, Wigan, Burnley, Hyndburn, Pendle, Rossendale, Calderdale and Kirklees.
Existing laws in Blackburn with Darwen and Bradford have also been amended which means those areas are now also subject to these measures.
Similar restrictions also apply to Leicester – the first place to be put in a local lockdown in June – under another set of laws which came into force on Monday, August 3.
Anyone caught breaking the rules could be fined £100 up to a maximum of £3,200 for repeat offences.
The restrictions will be reviewed for the first time on Wednesday, August 19 and must be reviewed once every fortnight.
According to the PA news agency, they could be in place for up to six months if they are not scrapped in the meantime.
The Government guidance still calls for people to following social distancing when they meet people from other households, and there are a number of exemptions to the rules including those in a support bubble, people sharing childcare, and moving house.