BOSTON (CBS) — There have now been 52 coronavirus cases linked to a cluster Brigham and Women’s Hospital in Boston. As of Tuesday, 39 employees and 13 patients had tested positive.

No new patients had been infected since Sept. 30, according to the hospital.

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Since Sept. 25, 8,544 coronavirus tests have been conducted on 7,250 employees. Although 39 positive cases were associated with the cluster, a total of 45 positive results came back. One result was determined to be unrelated to the cluster and the other five are under investigation.

According to the hospital’s Infection Control team, the cluster is contained to two inpatient units – 16A and 14CD of Braunwald Tower.

The hospital said all current inpatients have been tested for COVID-19 and will be tested again every three days along with daily screenings for symptoms. All patients are tested upon arrival at the hospital as well.

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Any employees who may have been exposed were notified and tested. Those who are at a higher risk will be tested every three days. Testing is also available to asymptomatic employees who would like to be tested.

It is unclear how the cluster spread, but the hospital listed the following contributing factors:

  • Many patients were not masked during clinical care/interactions with staff
  • Providers were inconsistent in their use of eye protection during patient encounters
  • The first patient who tested positive had received an aerosol-generating procedure prior to the positive test result
  • A staff member with mild symptoms, consistent with historical seasonal allergies, did not appreciate those symptoms as potentially related to COVID-19 and continued to work
  • Lack of physical distancing among staff while unmasked while eating

The source of the cluster is also under investigation by the Infection Control team.

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Visitors are still allowed to come to the hospital. Anyone who feels they have been exposed to coronavirus by the hospital will be tested for free.