BERLIN — As the Easter holiday approaches, world leaders and health officials are fervently warning that the hard-won gains in the fight against the coronavirus must not be jeopardized by relaxing social distancing.

A spike in deaths in Britain and New York and surges of reported new infections in Japan and in India’s congested cities make it clear that the battle is far from over.

“We are flattening the curve because we are rigorous about social distancing,” New York Gov. Andrew Cuomo said. “But it’s not a time to be complacent. It’s not a time to do anything different than we’ve been doing.”

The U.S. has by far the most confirmed cases, with over 430,000 people infected — three times the number of the next three countries combined. New York state on Wednesday recorded its highest one-day increase in deaths, 779, for an overall death toll of almost 6,300. New York has more than 40 percent of the U.S. death total of around 15,000.

In Germany, Health Minister Jens Spahn cautioned that the positive trend in reduced new infections “must be cemented.”

“So it is right to remain consistent over Easter,” he told the Handelsblatt newspaper Thursday. “Even if it is difficult in this weather, we should stay home and refrain from family visits so that the infection curve does not rise again.”

German Chancellor Angela Merkel also emphasized that people shouldn’t travel as usual, saying “even short trips inside Germany, to the seaside or the mountains or relatives, can’t happen over Easter this year.”

In New Zealand, police warned people not to drive to their holiday homes over Easter or they would be risking arrest.

“It’s simple – traveling to and from different towns and cities risks spreading COVID-19, and puts lives at risk,” police said.

Lithuania is restricting public movement and imposing a lockdown on major cities during Easter to prevent the further spread of infection in the predominantly Catholic nation.

Greece also tightened restrictions ahead of next week’s Orthodox Easter celebrations, increasing police roadblocks along highways and secondary roads, doubling fines for lockdown violations and banning travel between islands.

Swiss police were seeking to dissuade drivers from heading to the Italian-speaking Ticino region, the only part of Switzerland south of the Alps and one of the worst-hit by the pandemic. Roadblocks were being set up near the northern entrance of the Gotthard tunnel to separate out would-be visitors.

In the Middle East, Iran’s Supreme Leader Ayatollah Ali Khamenei suggested mass gatherings may be barred through the holy Muslim fasting month of Ramadan, which runs this year from late April through most of May.

Khamenei urged Shiite faithful to pray at home during Ramadan. Shiites typically pray together and communities often share meals, especially during Ramadan. Iran has reported over 66,000 coronavirus cases and over 4,100 deaths, although experts suspect those numbers under-report the country’s outbreak.

Dr. Anthony Fauci, a U.S. infectious diseases expert, said the Trump administration has been working on plans to eventually reopen the country but added it’s not time to scale back social distancing yet.

“Keep your foot on the accelerator because this is what is going to get us through this,” he said.

Fauci said the coronavirus pandemic will demand permanent changes in people’s behavior until a vaccine is developed. He said everyone should be constantly washing their hands and sick children and adults should not go to school or work.

“Don’t anybody ever shake hands again,” he said. “I mean, it sounds crazy, but that’s the way it’s really got to be until we get to a point where we know the population is protected.”

In a potentially worrying development in South Korea, at least 74 people diagnosed as having recovered from the new coronavirus tested positive for a second time after being released from the hospital. Health authorities were testing their virus and serum samples to figure out whether they could again be infectious to others.

In Britain, Prime Minister Boris Johonson spent a third night in intensive care due to COVID-19 infection. On Wednesday night, authorities said he was improving and sitting up in bed. The country posted its highest death toll in a single day Wednesday, with 938 virus-related deaths, and feared it could break that record again Thursday.

Japan reported more than 500 new cases for the first time Thursday, a worrisome rise since it has the world’s oldest population and COVID-19 can be especially serious in the elderly.

Prime Minister Shinzo Abe has declared a state of emergency — but not a lockdown — in Tokyo and six other prefectures. Companies in the world’s third-largest economy have been slow to embrace working from home and Abe appears to be concerned about keeping the economy going. Many commuters jammed Tokyo’s streets as usual on Thursday.

But Tokyo Gov. Yuriko Koike, who has outlined business closure plans that are tougher than the Abe’s, said the city is in a dire situation and cannot delay non-essential business shutdowns for two more weeks.

“The spread of the infections is so fast in Tokyo that we cannot wait that long,” she said.

India, whose 1.3 billion people are under a lockdown until next week, has sealed off dozens of hot spots in and around New Delhi, the capital. It will supply residents with food and medicine but not allow them to leave. The number of confirmed cases exceeds 5,000, with 166 deaths.

Worldwide, the number of confirmed COVID-19 cases has climbed to nearly 1.5 million, with nearly 90,000 deaths, according to Johns Hopkins University. The true numbers are much higher, because of limited testing, different rules for counting the dead and the efforts of some governments to conceal the extent of their outbreaks.

For most, the virus causes mild to moderate symptoms like fever and cough. But for some older adults and the infirm, it can cause pneumonia and death. Almost 330,000 people have recovered.

U.S. Vice President Mike Pence said he would speak to African American leaders who are concerned about disproportionate impacts the virus is having on their communities. Fauci acknowledged that historic disparities in health care have put African Americans at risk for diseases that make them more vulnerable to the virus.

New virus infections, hospitalizations and deaths have been leveling off in hard-hit Italy and Spain, which together have more than 32,000 deaths, but the daily tolls are still shocking. Spain reported 683 more deaths on Thursday, bringing its total to 15,238.

The latest figures were released as Spanish Prime Minister Pedro Sánchez appeared before parliament to ask for a second two-week extension of Spain’s state of emergency.

Perry reported from Wellington, New Zealand and Becatoros from Athens, Greece. Associated Press journalists around the world contributed.