A virus outbreak at Jewish Care's Lady Sarah Cohen House left the 120-bed Friern Barnet residential home closed to visitors last week.
Jewish Care director of care and community services Neil Taylor said the virus was "similar to that being experienced in other health care facilities across the UK at this time of year.
"Jewish Care works closely with the Health Protection Agency and uses a variety of policies and procedures to limit the further spread of such viruses. The decision to close the home to visitors is one of the procedures they recommend."