This follows a surge in Covid-19 infections in recent weeks.
Last weekend alone there were four deaths at the main hospital in Buka and nine cases detected on Monday and Tuesday.
During the lockdown, issued by the regional pandemic controller, Clement Totavun, all educational institutions are to continue to operate, but at new hours of 8am to 2pm.
The main town markets are to close, but road side markets can still trade.
Other businesses, and government offices, can remain open but must apply the safety protocols.