BAGHDAD  Less than a day after a suicide bomber killed more than 50 people in a crowd of Shiite pilgrims at a police checkpoint in Baghdad, more explosions struck worshipers on Thursday, killing 7 and wounding about 60 despite intensive efforts by Iraqi security forces to foil such attacks.

At least five other Shiites were killed and dozens of others wounded in and around Baghdad on Wednesday, as hundreds of thousands of people took part in the annual procession to Kadhimiya’s gold-domed shrine to honor the eighth-century Imam Musa al-Kadhim.

Shiite pilgrims are frequent targets of Sunni insurgent groups, and this year Iraqi security forces ordered several major roads and bridges closed and banned bicycles and motorcycles in the capital to try to safeguard the marchers.

Some 200,000 security force members had been assigned to patrol streets, check cars and search pilgrims as they walked along streets to the shrine.