New data shows nearly 150,000 people on average in England were carrying coronavirus outside hospitals and care homes over a two-week period.
The figure was higher for people working in front-line healthcare roles, such as NHS staff and care workers. They showed no difference in the rate of infection in any particular age group.
Scientists worldwide racing to understand the new virus believe Covid-19 affects the elderly most severely - while studies have suggested young people may catch and spread it without ever noticing symptoms.
British authorities have urged over-70s, people with underlying health conditions and pregnant women to self-isolate during the country's lockdown.