LONDON (REUTERS) - Britain's Health Ministry on Saturday (Nov 6) said it would open up bookings for booster shots a month before people were eligible to receive the shots to help speed up the roll-out ahead of the challenging winter months.

Prime Minister Boris Johnson is relying on booster doses as a major plank of his plan to avoid lockdown this winter through Covid-19 vaccines rather than social distancing rules or mask mandates, but has been criticised for a slow start to the programme.

Around three in five eligible over-50s have had booster shots in Britain, with more than nine million people getting booster doses in the country overall so far.

Over-50s and vulnerable people will still become eligible for their booster shots six months after their second dose. But, from Monday, they can book the appointment after five months.

Currently, people can only book the appointment six months after their second dose.

"This will accelerate the booster programme, ensure the National Health Service is able to vaccinate people as quickly as possible, and importantly help more people maintain protection against Covid-19 as we know immunity will dip over time," Health Secretary Sajid Javid, who sets policy in Britain, said.

The Health Ministry said that the winter would be challenging for the NHS, owing to increased spread of other seasonal viruses such as flu.

Britain is currently reporting an average of 40,000 new cases each day. Even though vaccines have greatly reduced deaths from Covid-19, doctors are warning that pressures are building inside hospitals.

Mr Johnson has so far resisted calls for a "Plan B" involving mask mandates, vaccine passes and work-from-home directives, and Mr Javid has said that while the NHS faces "huge" pressure, it is not currently unsustainable pressure.

"Covid-19 vaccines are the best way to protect yourself and your family ahead of a challenging winter and this change to the booking system will make it as easy as possible for people to book their booster jabs," Mr Javid said.