Here is a summary of each phase:
During this phase, officials aimed to detect and isolate early cases and trace people who have been in contact with those infected.
The aim of this phase was to prevent the virus from spreading widely across the country.
The aim of this phase is to slow the spread of the virus, reducing the impact and pushing it away from the winter season.
The Government believes that if the peak of the virus can be delayed until warmer months, it can reduce the risk of overlapping with seasonal flu and other challenges that the colder months bring.
Coronavirus: Everything you need to know
Officials are examining the most effective ways to slow the spread of the virus.
They say the public can help delay the peak of the infection with simple measures including adhering to the "catch it, bin it, kill it" strategy for sneezing and coughing, and hand-washing.
Next steps for the delay phase include the possibility of school closures, encouraging more home working, and reducing large-scale gatherings.
The research phase
Experts are constantly monitoring and researching the virus with the aim of reducing its impact.
Research takes various forms including looking into new diagnostic tests, drugs to treat Covid-19, preventative vaccines, and coming up with the best course of care for people affected.
The mitigate phase
In the event of the outbreak worsening, or a severe, prolonged pandemic, the response will escalate and the focus will move away from "contain" and "delay" to "mitigate".
This phase involves providing the best care for people who become ill, supporting hospitals, and ensuring support for those who become infected but do not require hospital treatment.
It also involves plans to minimise the impact of disease on society, public services and the economy.
The next steps in the mitigate phase could include emergency services focusing on critical functions - for instance, this could mean police concentrating on responding to serious offences and maintaining public order if the number of officers dwindles.
In hospitals, non-urgent cases could be delayed and staff leavers and retirees could be called back to duty.