VALLETTA, Dec 29 (Reuters) - Malta registered a record number of COVID-19 infections on Wednesday as the United States added the Mediterranean island to its highest-risk category for travel and urged its citizens not to visit. Health authorities said 1,337 new COVID-19 infections were detected, marking a record high for the second day in a row. It is the fifth time in eight days that the number of new daily infections hit a national record. However, hospitalisations stayed low at just 82 virus patients. The U.S. Centers for Disease Control advised against travel to Malta late on Tuesday, placing the country at the Level 4, "Very High" category, where more than 500 cases per 100,000 residents are registered in the previous 28 days. "Because of the current situation in Malta, even fully vaccinated travellers may be at risk of getting and spreading COVID-19 variants," the advisory said. The increase in infections came despite a high rate of vaccination, with 95% of Malta residents having received two doses of a vaccine. The island is currently vaccinating children aged over five. Health Minister Chris Fearne also said on Tuesday that 200,000 – out of a population of some 500,000 - had already taken the booster dose. Business lobby groups on Wednesday urged the government to reduce a two-week quarantine period for patients and those who come into contact with them, saying it was impacting the economy. The Times of Malta newspaper reported that at least 20,000 people were currently in quarantine – four times the population of the capital, Valletta.