The Monaco Grand Prix has been cancelled and the Dutch and Spanish races have been postponed due to the coronavirus outbreak.
The first four races in Australia, Bahrain, Vietnam and China had already been called off due to the pandemic.
The sport's governing body, the FIA, says it expects the 2020 season to begin "as soon as it is safe to do so after May".
Monaco organisers said it was "not possible" to rearrange a date.
It is still hoped the other two races can be rescheduled later in the year.