Students at Aylsham High School have been asked to wear facemasks at the school and on public transport following a rise in Covid cases.
Duncan Spalding, headteacher, did not say how many of the school's staff or students had tested positive, but said the rate was still "well below" the national average.
Mr Spalding said: "As a precautionary measure we are asking students to make sure they wear masks on school and public transport and in communal areas around the school.
"This is in response to an increase in cases which mirrors a rise in community cases. Our numbers are still well below national rates but we believe it is important to be proactive rather than reactive.
"We know that a number of other secondary schools have already acted in a similar fashion in response to higher rates of infection."
Mr Spalding said no other routines or systems had been changed at the school. He added: "We have had a fabulous start to the term and want to ensure that the run in to half-term is not unduly disrupted."
Latest government data - for the week up to October 6 - showed there were 29 reported cases in the Aylsham area, up by 14 on the previous seven days. The case number for Norfolk over the same period was 3,019. This equated to a case rate of 330 per 100,000 people.
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