Among 100,000 volunteers tested last month one in 120 were positive compared with one in 40 aged five to 17.
The infection rate was rising in under 18s and falling for 18-54s, the REACT-1 study found.
Health Secretary Sajid Javid said: “These findings shows how important it is for young people to get the jab to protect them from Covid-19.” Professor Paul Elliott, of REACT, said: “Households with children also had a higher prevalence of infection, suggesting that children may be passing on the virus.”
Yesterday’s figures revealed 42,776 positive tests in the previous 24 hours and 136 deaths linked to the virus.
Meanwhile, the NHS is urging parents to give their toddlers the flu jab.