Violence is a threat Haitians know. Covid is something new.

Haiti, the only country in the Americas without a Covid-19 vaccine campaign, is also the country with one of the world’s most dysfunctional health care systems.

Even as Haitians struggle to understand a shifting political crisis in the wake of the assassination of the nation’s president and worry about a surge in violence on the streets, looming in the backdrop is a pandemic whose scale is essentially unknown.

The country of 11 million people has yet to receive its first doses from the Covax vaccine-sharing program, making it one of few places that have not started an inoculation campaign.

Having never fully recovered from a 2010 earthquake that destroyed the Health Ministry’s building and 50 health care centers, Haiti has long depended on billions of dollars of foreign aid and the work of nongovernmental organizations to provide basic services.

But even before the assassination of President Jovenel Moïse this week, violence posed an increasing challenge to those working to deliver assistance. Humanitarian groups have become primary targets, and last month Doctors Without Borders evacuated some of its staff members and closed an emergency center in Haiti after gangs attacked it.

The dozens of armed gangs that control more than a third of the capital have also killed hundreds of people and impelled thousands to flee their homes over the past year.

International organizations and humanitarian groups warn that the assassination threatens to worsen a crisis that has been building for more than a year, ever since Mr. Moise’s decision to remain in office after opponents said his term had expired essentially paralyzed the government.

In the first two weeks of June, UNICEF says, 8,500 women and children fled their homes to escape violence. “Every time, clashes between armed groups are more violent, and every time more women and children are forced to flee their homes,” Bruno Maes, UNICEF’s Haiti representative, said in a statement at the time.

“Since the beginning of this year, insecurity has been escalating. But the capital city is now facing an urban guerrilla, with thousands of children and women caught in the crossfire,” Mr. Maes added. “The displaced families I’ve talked to have lost everything and urgently need clean water, food, personal hygiene items, mattresses, blankets and clothes.”

Less than three weeks after Mr. Maes made those remarks, the president was gunned down.

Against this backdrop, the pandemic many in the country have viewed the pandemic as an abstraction. But there are indications that the coronavirus is far more widespread than officially reported.

The neighboring Dominican Republic, which has roughly the same size population, has reported more than 330,000 cases and nearly 4,000 deaths. Haiti has registered 19,000 cases and 467 deaths — but hospitals have reported struggling in recent weeks to find enough oxygen for a surge in patients.

The Rev. Richard Frechette, a doctor at St. Luke’s Hospital in Port-au-Prince, told the humanitarian aid organization Direct Relief that he had pleaded with gang leaders to allow the delivery of critical supplies, including oxygen.

“If the streets turn into looting and riots, we’re not going to be able to get oxygen,” he said. “That always happens when there’s instability.”

Haiti is due to receive about six million coronavirus vaccine doses from the United States, but it is unclear when they might be delivered.