Context:
Last year, the drug also faced headwinds as a trickle of case studies highlighted the need for caution when using it in elderly patients, who are amongst the most likely to suffer from increased bleeding associated with anticoagulants. A larger setback also came as regulators in Australia, Japan, and Europe warned doctors about serious bleeding-related side effects.
NOT A TEACHER
I believe that it is just the OPPOSITE.
My dictionary tells me that "a trickle" means "a small group.'