LONDON, Oct 5 (Reuters) - School absences in England related to COVID-19 jumped by two-thirds in the last two weeks of September, according to government data which could raise concerns about further disruption to education despite a pledge to keep schools open. Around one in seven secondary school students were off for either coronavirus-related or other reasons, the Department for Education said, and the age group has the highest prevalence of infections in the country. read more Schools in England have been open for around a month, and some epidemiologists have highlighted concern about rising cases among children, although it is yet to translate into a sustained increase in infections for the population more broadly. An estimated 204,000 students, or 2.5% of all pupils, at state-funded schools were off for COVID-19 related reasons on Sept. 30, up from 122,000 on Sept. 16, according to Tuesday"s figures. Although overall attendance in state-funded primary schools was 92.6% on that day, in secondary schools, attendance was substantially lower, at 86.3%. Increased prevalence of COVID-19 among secondary school-age children contributed to a rise in overall infection numbers in the latest weekly figures announced on Friday by the Office for National Statistics. read more Prime Minister Boris Johnson has vowed to keep schools open as a priority this academic year, after the pandemic heavily disrupted education for months. Children between 12- to 15-years-old are being offered COVID-19 vaccines after Johnson"s medical advisers last month found that the benefit to children gained by avoiding further disruption to schooling was decisive even as the benefit of protection against COVID-19 itself was marginal. read more