NAV has posted the following announcement (in Norwegian) on their website: “Due to the coronavirus, only a limited number of sea service books will be issued during the pandemic period. If necessary, sea service books will be issued by agreement for seafarers on vessels engaged on foreign voyages. This will not be the case for seafarers on vessels engaged on domestic voyages who, strictly speaking, do not need a sea service book.”
Click here to get more information (in Norwegian only). You can also find out who you can contact at NAV to get more information about sea service books.