A one-year-old boy remains in a critical condition in a Hong Kong hospital after contracting Covid-19, the second infant confirmed as severely infected with the contagious disease within a week, according to health authorities.The Centre for Health Protection at the Department of Health said on Friday that both boys had good past health but had not been inoculated against Covid-19.The centre urged unvaccinated high-risk groups to get vaccinated, warning that the overall Covid-19 activity could increase in the coming one or two months.The one-year-old boy developed a fever, cough and runny nose on June 2 and the next day showed symptoms of stridor, a blockage of the upper airway.He was admitted to Alice Ho Miu Ling Nethersole Hospital on June 4 and was later transferred to the paediatric intensive care unit at Prince of Wales Hospital due to severe croup symptoms.The centre said the boy’s diagnosis was Covid-19 complicated with croup.“He is currently in critical condition,” it said.