The Centers for Disease Control and Prevention is looking into a "handful" of reports of additional adverse side effects to the Johnson & Johnson vaccine.

CDC officials have not said what those side effects are. "These have been a handful of cases, not an overwhelming number of cases. We are working through adjudicating them and verifying whether they do in fact reflect a true case. And that will be the work of the CDC this week, as well as the FDA," says CDC Director Rochelle Walensky.

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The CDC and FDA will present their findings to an advisory panel that meets this Friday.

Administering the Johnson & Johnson vaccine has been on pause since last week after several cases of rare blood clots were found.

Meanwhile, the FDA has shut down vaccine production at Johnson & Johnson’s Baltimore facility. The facility has been linked to quality control problems that ruined 15 million J&J doses.

The disruption jeopardizes the drugmaker's pledge to deliver 100 million doses by the end of June.

It says it intends to fulfill its commitment, having delivered about 18 million shots so far and that it's premature to speculate on the bad batch's impact