China finally came out of a 3-year-long isolation Sunday as the country reopened its borders to foreign visitors for the first time since the start of the COVID-19 pandemic.

The decision dismantled a final pillar of a zero-COVID policy that had shielded China's 1.4 billion people from the virus but also cut them off from the rest of the world.

After three long years, mainland China opened sea and land crossings with Hong Kong and ended a requirement for incoming travelers to quarantine.

Travelers streamed into China by air, land and sea on Sunday, many eager for long-awaited reunions.

China's easing over the past month of one of the world's tightest COVID regimes followed historic protests against a policy that included frequent testing, curbs on movement and mass lockdowns that heavily damaged the second-biggest economy.

Long queues formed at the Hong Kong international airport's check-in counters for flights to mainland cities including Beijing, Tianjin and Xiamen. Hong Kong media outlets estimated that thousands were crossing.

"I'm so happy, so happy, so excited. I haven't seen my parents for many years," said Hong Kong resident Teresa Chow as she and dozens of other travelers prepared to cross into mainland China from Hong Kong's Lok Ma Chau checkpoint.

"My parents are not in good health and I couldn't go back to see them even when they had colon cancer, so I'm really happy to go back and see them now," she said.

Investors hope the reopening will reinvigorate a $17 trillion economy suffering its slowest growth in nearly half a century. But the abrupt policy reversal has triggered a massive wave of infections that is overwhelming some hospitals and causing business disruptions.

The border opening follows Saturday's start of "chun yun," the 40-day period of Lunar New Year travel, which before the pandemic was the world's largest annual migration, as people returned to their hometowns or took holidays with family.

Some 2 billion trips are expected this season, nearly double last year's movement and recovering to 70% of 2019 levels, the government says.

Many Chinese are also expected to start traveling abroad, a long-awaited shift for tourist spots in countries such as Thailand and Indonesia. But several governments – worried about China's COVID spike – are imposing curbs on travelers from the country.

Travel will not quickly return to pre-pandemic levels due to such factors as a dearth of international flights, analysts say.

China on Sunday resumed issuing passports and travel visas for mainland residents, and ordinary visas and residence permits for foreigners. Beijing has quotas on the number of people who can travel between Hong Kong and China daily.

Visitors, homecomings

At the Beijing Capital International Airport, families and friends exchanged emotional hugs and greetings with passengers arriving from places such as Hong Kong, Warsaw and Frankfurt, meetings impossible just a day earlier.

"I've been looking forward to the reopening for a long time. Finally, we are reconnected with the world. I'm thrilled, I can't believe it’s happening," said a businesswoman surnamed Shen, 55, who flew in from Hong Kong.

Others waiting at the airport included a group of women with long-lens cameras hoping to catch a glimpse of the boy band Tempest, the first idol group from South Korea to enter China in three years.

"It’s so good to see them in person! They are much more handsome and taller than I expected," said a 19-year-old who gave her name as Xiny, after chasing the seven-member group, who arrived in Beijing from Seoul.

Concerns over rural areas

China downgraded its COVID management to Category B from A, which had allowed local authorities to quarantine patients and their close contacts and lock down regions.

But concerns remain that the great migration of city workers to their hometowns and reopening of borders may cause a surge in infections in smaller towns and rural areas that are less equipped with intensive-care beds and ventilators.

The World Health Organisation (WHO) said on Wednesday that China's COVID data underrepresents the number of hospitalizations and deaths from the disease.

Chinese officials and state media defended the handling of the outbreak, playing down the severity of the surge and denouncing foreign travel requirements on Chinese residents.

Jiao Yahui, an official from the National Health Commission, said in an interview published by state broadcaster CCTV on Sunday that demand for emergency and critical care in China's large cities had likely peaked but was rising fast in small and midsize cities and rural areas due to the Lunar New Year travel.

Some 80% of ICU beds in China's top- and second-tier hospitals were in use, up from 54% on Dec. 25, she said, adding that the country's medical services to treat COVID were facing an "unprecedented challenge."

Health officials told a news conference they would not rule out the possibility of taking emergency COVID prevention measures such as suspending nonessential large-scale activities and business at large entertainment venues to deal with large outbreaks.

China's Center for Disease Control and Prevention announced two new daily COVID deaths on the mainland, compared with three a day earlier, bringing the official death toll to 5,269.