On 19 March, Ardern stated that New Zealand's borders would be closed to all non-citizens and non-permanent residents, after 11:59 pm on 20 March (NZDT). Ardern announced that New Zealand would move to alert level 4, including a nationwide lockdown, at 11:59 pm on 25 March.
On 19 March 2020, as the COVID-19 pandemic hit the United Kingdom, the Queen moved to Windsor Castle and sequestered there as a precaution. Public engagements were cancelled and Windsor Castle followed a strict sanitary protocol nicknamed "HMS Bubble".