RIGA, Oct 18 (Reuters) - Latvia announced a COVID-19 lockdown from Oct. 21 until Nov. 15 to try to slow a spike in infections in one of the least vaccinated European Union countries. "Our health system is in danger ... The only way out of this crisis is to get vaccinated," Prime Minister Krisjanis Karins said after an emergency government meeting, blaming low vaccination rates for the spike in hospitalisations. Only 54% of Latvian adults have been fully vaccinated, well below EU average of 74%, EU figures show. "I have to apologise to the already vaccinated," Karins said, announcing that shops, restaurants, schools and entertainment will be closed, with only essential services available and a curfew in place from 8 p.m. to 5 a.m. Only essential manufacturing, construction and critical jobs will be allowed to continue in person. One of the two largest Riga hospitals began installing makeshift beds for COVID-19 patients in its atrium to cope with the influx, the national broadcaster reported. No travel restrictions were announced "since infection rates elsewhere are much lower, and we don"t see immediate risks", Karins said. New cases in Latvia increased by 49% in the week to Sunday, its health authority said, according to the BNS wire. The Latvian government cancelled most planned hospital operations last week amid an increased need for beds and staff as COVID-19 cases climb. The country had reported the second-worst infection numbers in the EU, after neighbour Lithuania, in the fortnight to Oct. 10, with 864 new cases per 10,000 people. Latvian President Egils Levits tested positive last week, prompting Finland"s President Sauli Niinisto, who had had breakfast with Levits a day earlier, to self-isolate. read more