The streets of Istanbul were abuzz, the grocery stores packed, the seaside promenades crowded — but it was not the bustle of an ordinary spring Thursday. People were flocking to take advantage of the last day before a new lockdown takes hold, the strictest in Turkey since the pandemic began.

Daily reports of new coronavirus cases rose swiftly in the country after the government started lifting earlier safety strictures in March, and are now generally around 40,000 a day, according to official figures, with some days reaching 60,000 or more. The health care system is swamped with patients, and the country set a grim record last week with 362 Covid deaths reported in a single day.

The country’s heath minister, Fahrettin Koca, has said that more contagious variants of the virus are partly to blame for the accelerating spread. Critics say the government relaxed too soon in March, before the country had made much progress with vaccination.

Turkey has fully vaccinated only about 11 percent of its people so far — 8.8 million out of a population of 83 million — using mainly the CoronaVac vaccine developed in China and the Pfizer-BioNtech vaccine. It has had a hard time securing more doses, and has resorted to postponing second doses to stretch its supply. But Mr. Koca said he expects 30 million more doses of the Pfizer vaccine in June, and to soon add the Sputnik V vaccine from Russia to its effort.

“Vaccine procurement will be difficult in the next two months,” Mr. Koca said in a video statement on Thursday. ‘’But then we expect to have abundance of vaccines.’’

For weeks, scientists have been calling for a total lockdown to stem the surge, but President Recep Tayyip Erdogan held off, mainly for economic reasons. He changed course after a cabinet meeting on Monday, and announced a new three-week lockdown to take effect Thursday evening and last through the end of Ramadan.

Many people will be required to stay home except for essential errands or to go to certain jobs. Schools, kindergartens and day care centers will be closed. Grocery stores will be open, but only for customers who live within walking distance. Even solitary outdoor exercise will be banned.

The announcement prompted a rush to stock up on groceries, alcohol and other supplies for the lockdown, which will include Eid al-Fitr, the three-day festival to mark the end of Ramadan. And many city dwellers hurried to reach rural hometowns or holiday resorts while travel was still allowed.

Though Mr. Erdogan billed the new restrictions as “a full lockdown,” an association of labor unions known as DISK estimated that 61 percent of all workers in Turkey are employed in sectors that are exempt from the lockdown, including manufacturing, construction, agriculture and transportation.

Gokhan Aydin, 45, who works in a cable factory in Bursa, said he and his coworkers “would have loved to be part of the full lockdown, without loss of income, as the virus peaked.” Though his factory has good Covid precautions, he said, he is still worried because the virus is everywhere.

The lockdown will land hardest on the many Turks who depend on informal day work. A single mother with five small children in Istanbul who collects and sells paper said her family can eat only on days when she can work.

“I really don’t know what to do,” she said, speaking on the condition of anonymity to avoid jeopardizing her welfare payments from the government. “I wish the state would give me a job.”