People attending nightclubs and SLOTXO other venues where large crowds gather in England will need to be fully vaccinated from the end of September, the government says. Latest figures show 35% of 18 to 30-year-olds have not had their first jab. Currently nightclubs and other crowded venues are only encouraged to ask clubbers to show proof of vaccination, a negative test result or immunity. But Boris Johnson said he was concerned by the continuing risk of transmission. The announcement came on the day nightclubs in England were allowed to reopen after 16 months of closure. The prime minister told a press conference on Monday: "I don't want to have to close nightclubs again as they have elsewhere. But it does mean nightclubs need to do the socially responsible thing. "As we said last week, we do reserve the right to mandate certification at any point if it's necessary to reduce transmission. "And I should serve notice now that by the end of September, when all over 18s have had their chance to be double jabbed we're planning to make full vaccination the condition of entry to nightclubs and other venues where large crowds gather." Chief scientific adviser Sir Patrick Vallance said nightclubs and other such venues could be "potential super spreading events" because of crowds in close contact. "I would expect that with opening of nightclubs, we'll continue to see an increase in cases, and we will see outbreaks related to specific nightclubs as well," he said. Nightclubs are still closed in Scotland, Wales and Northern Ireland. The Welsh government said it would never mandate the use of vaccination certificates but that businesses would be free to ask for them. Across the UK, 39,950 cases were recorded on Monday alongside another 19 deaths within 28 days of a positive test.