At Monday's Welsh Government press conference, the First Minister announced that Wales would enter a 17-day national lockdown to prevent the further spread of coronavirus in the country.
COVID-19 cases in Wales have continued to rise in recent weeks, despite almost 2.5m people living under local restrictions.
Other regions have since followed, but the restrictions will now be replaced by new national rules announced by Mark Drakeford.
The fire-break is being introduced to prevent the pressure on health services in Wales from growing, with warnings from both the First Minister and the chief executive of NHS Wales that critical care was at capacity.
"It doesn't take much with the maths involved to see a system under pressure," Dr Andrew Goodall said.
"It is quite possible that without action we could see the NHS in Wales under pressure within a month."
The action from Welsh Government is an immediate response to those concerns, with evidence from the Technical Advisory Group saying that if the fire-break is "strict and well-adhered" to as the restrictions in late May, it could put the epidemic back by approximately 28 days or more.
So now action has been taken, and Wales prepares to enter its second strict national lockdown, we look at the evidence that the Welsh Government used to make their decision.
The current rate of transmission in Wales is around 1.4 - as opposed to 3.0 when restrictions were introduced in March. So, what are the reasons behind the closure of non-essential shops, pubs, restaurants and schools?
The evidence shows that by reverting to the original lockdown rules, the rate could be brought down by more than 2.0.
It also shows that the incidence of the virus has risen in all age groups, but it is highest in those aged under 50.
Why are we being told to work from home?
Welsh Government have always made it clear that their position was that people should work from home where possible.
The evidence recognises that the transmission risk in workplace settings "varies significantly" with the particular environment, activities and worker behaviours.
It does state that 30% of the population is currently working from home.
Why can we now not meet our extended bubbles outside of our households?
When implementing the local lockdown restrictions across Wales, the government suggested that large amounts of transmission was taking place in households.
The evidence suggests that stopping all contacts between different households could reduce the rate of transmission by 0.1-0.2.
It says the "bubbling" of single occupancy households has little effect on the R rate. This explains why the Welsh Government has allowed for adults living alone to form a bubble with another household during this fire-break lockdown.
Why are pubs, restaurants and cafés closing?
The Technical Advisory Group estimates that by closing pubs, restaurants and cafés, the transmission rate could also be reduced by 0.1-0.2.
This is due to the fact that there are many risks in bars and pubs that are likely to be higher than other indoor settings such as the close proximity of people, longer duration of exposure without wearing a face covering, loud talking and the impact that the consumption of alcohol has on people’s behaviour.
Some venues are also poorly ventilated which could pose a greater risk of spreading the virus especially as we enter the winter months.
Why gyms and fitness centres have been closed?
The evidence released by the Welsh Government says that by closing gyms there could be a potential reduction of 0.1 in the R rate.
The technical advice says that there is evidence to suggest that an outbreak in Korea was associated with a fitness class.
This is because of the environmental risks linked to high touch surfaces, higher aerosol generation and breathing rates due to aerobic activity.
Why are places of worship and community centres being closed?
The evidence gathered from other countries shows that some outbreaks can be attributed to places of worship.
Cases rose in religious communities in South Korea, Singapore and in Germany.
The evidence suggests that by bringing in this ban it can help reduce the R-rate by 0.1, although this depends on the suitably of different buildings.
Restrictions on outdoor gatherings, the closure of non-essential shops and close-contact personal services.
Non-essential retail will be closed from Friday with the evidence suggesting that some outbreaks in China can be attributed to shops. The evidence does recognise that this will have "very limited impact" on the R rate.
Speaking at a Welsh Government press conference on Wednesday the economy minister Ken Skates said: "It will make a significant difference.
"We want this to be a short, sharp shock to make sure that they make it through the Christmas period."
Why are only secondary schools being closed?
Mark Drakeford announced on Monday that secondary schools would be closed for a period of two weeks to help slow the spread.
Speaking at the press conference, Mr Drakeford said: "Primary and special schools will reopen as normal after half-term.
"Secondary schools will reopen after the half-term for children in years seven and eight. Pupils will be able to come in to take exams but other pupils will continue their learning from home for an extra week."
The evidence suggests that the temporary closure of secondary schools could reduce the R rate in Wales by 0.35.
Primary schools are exempt as the evidence suggests that transmission to and from younger children to be more limited.
Another reason why the Welsh Government has suggested another national lockdown is because the previous rules introduced in March helped reduce the R rate from 3.0 to around 0.5.
Evidence shows that the success of the initial lockdown was due to a high level of uptake from the population and it resulted in a reduction in transmission of 75%.
Speaking at his press conference on Monday. Mr Drakeford said that it would take an effort from the whole population to "end the pandemic".
It is with a heavy heart that I once again ask everyone to stay at home and businesses to shut.
"We are all tired of coronavirus and the many rules and regulations we all have to live with," he continued.
"We all want to see an end to this pandemic and our lives returned to us.
"This is our best chance of regaining control of the virus and avoiding a much longer – and damaging – national lockdown. We have a small window of opportunity to act.
"To be successful, we need everyone’s help. Here in Wales, this is the moment to come together; to play our part in a common endeavour to once again protect the NHS and save lives."
The evidence from the technical advisory group concludes by saying, "Without intervention, continued increase of cases of Covid-19 in Wales, in hospitals and in ICU will be too high for the NHS to sustain.
"In order to balance the four harms effectively, TAC recommends urgent consideration and execution of a hard national fire break to massively reduce transmission for a period of weeks, reduce the number of cases to a sustainable level and then a set of sustainable, national interventions to keep Rt around 1 while maximising social, economic and health benefits."