Covid-19 vaccine makers are shifting gears and planning for a smaller, more competitive booster shot market after delivering as many doses as fast as they could over the last 18 months.

Executives at the biggest Covid-19 vaccine makers including Pfizer Inc and Moderna Inc said they believe most people who wanted to get vaccinated against the disease have already done so - more than 5 billion people worldwide.

In the coming year, most Covid-19 vaccinations will be booster shots, or first inoculations for children, which are still gaining regulatory approvals around the world, they said.

Pfizer, which...