London, April 15 : About half of the UK's adult population were estimated to have tested positive for coronavirus antibodies by the end of March, the latest data from the Office for National Statistics (ONS) revealed. An estimated 54.9 per cent of people in private households in England had Covid-19 antibodies in the week to March 28, Xinhua news agency quoted the ONS as saying on Wednesday. Meanwhile, people in older age groups showed a slight decrease in antibody positivity for the week ending March 28, according to the ONS. The ONS said that this is likely because the data does not yet show the impact of second doses of Covid-19 vaccinations. It is understood that it takes between two and three weeks after an infection or vaccination for the body to make enough antibodies. But studies haven't yet shown that having detectable antibodies affects the chance of contracting the virus. The ONS survey included people aged 16 years and over in private residential households, and it excludes people in hospitals and care homes. All shops reopened from Monday along with hairdressers, beauty salons and other close-contact services. Restaurants and pubs were allowed to serve food and alcohol to customers sitting outdoors. Meanwhile, gyms, spas, zoos, theme parks, libraries and community centres can all open. On May 17, restaurants and pubs are expected be allowed to resume indoor service and see most rules on gathering outdoors lifted. More than 32.2 million people have been given the first jab of the coronavirus vaccine, according to the latest official figures. Experts have warned that despite progress in vaccine rollout, Britain is "still not out of the woods" amid concerns over new variants and the third wave of pandemic on the European continent. /IANS