NIAMEY, Niger—This desert capital’s main coronavirus ward has been empty for months and hastily erected isolation facilities are gathering dust. Masks are almost unheard of in the streets and many days go by without a single person testing positive for Covid-19. There is so little demand for vaccines that the government has sent thousands of doses abroad.

Welcome to Niger, the land that coronavirus somehow forgot.

This vast West African nation—home to one of the world’s highest birth and poverty rates—was once identified by the World Health Organization as one of the most vulnerable to the coronavirus outbreak on a continent that the United Nations predicted would kill millions. Over a year later, many other countries across Africa are in the grip of the pandemic’s third wave, with new variants sending infections to record levels. 

But while Niger is struggling with a host of economic and security challenges, it is among a small group of nations on the southern edge of the Sahara that so far has mostly escaped the coronavirus scourge. The reasons—which appear to include a hot and dry climate, sparsely populated and poorly connected settlements and the world’s youngest population—have made Niger a crucial case study for virologists studying the evolution of Covid-19, experts say.

Doctors say the spread of the highly transmissible Delta variant and the reopening of land borders in recent weeks still poses a threat to the largely unvaccinated country and its health system. But in Niamey, the quiet capital perched on the river Niger, there is little evidence of the pandemic raging in many other countries across the continent.