Alaska Airlines, and its subsidiary Horizon Air, have joined the list of U.S. airlines taking steps to boost the COVID-19 vaccination rate among employees.

Alaska announced last week that all new employees must be vaccinated against COVID-19 before being hired. The new rule took effect immediately.

Unvaccinated employees already on the payroll will need to participate in a “vaccine education program,” the airline said. And unvaccinated employees will no longer be eligible for special COVID-19 pay if they test positive or need to take time off work after exposure to an infected individua...