The concentration of coronavirus detected in Nantucket sewage has soared to a record-breaking level in the latest sample taken at the town’s Surfside Wastewater Treatment Facility.
The sample, collected on Dec. 27 and analyzed by the company Biobot, puts Nantucket in the 91st percentile for virus concentration in wastewater compared to other communities that conduct similar testing. The estimated incidence rate based on the concentration of the SARS-CoV-2 virus detected in island sewage would equate to 55 new cases per day. See the full report here.
The town has funded weekly sewage testing on the island as a tool to provide policymakers and health officials with an early-warning sign of a pending surge of COVID-19 cases.
New COVID-19 cases diagnosed through testing have indeed spiked (although the latest data is from Dec. 29), but the island’s high vaccination rate has generally protected Nantucket’s population from more severe cases resulting in hospitalizations or deaths, public health officials said.
“Though we are seeing a significant spike of cases, this is not unexpected as the seasonality of airborne viruses is well known,” Nantucket Health Department Director Roberto Santamaria told the Current in a recent interview. “With Nantucket’s high vaccination rate, we hope to continue the trend of low hospitalization this winter”
Nantucket’s Board of Health has closely watched the weekly wastewater testing reports provided by Biobot, with Santamaria calling the metric the most reliable data point in assessing the prevalence of coronavirus in the community. For several months, the Board of Health implemented a policy that automatically triggered an indoor mask order if the concentration of coronavirus exceeded the 50th percentile compared to other communities. But Santamaria emphasized at the board’s December meeting that using the wastewater metric as the sole basis for policy decisions was a volatile proposition. The board agreed, and voted last month to ditch the policy and implement an islandwide mask advisory, but no mandate.
Last Friday, Nantucket Cottage Hospital (NCH) reported four patients were hospitalized with COVID-19, which would be among the highest, if not the highest, number of patients admitted to the hospital due to the virus at one time during the entire pandemic. But it was still not a number that threatened to overwhelm the hospital’s ability to provide care.
The vaccination status of those patients is not known. While other hospitals report that information, NCH cited privacy concerns as the reason for not providing the vaccination status of those patients being treated for COVID-19. “We recognize that other hospitals in larger metropolitan areas are releasing the vaccination status of COVID-19 patients, but due to the small pool of patients here at NCH, we’ve opted to limit the amount of additional information we’re releasing out of respect for patient privacy,” hospital public information manager James Lanza said.
The spike in coronavirus detected in Nantucket sewage mimics a similar surge observed in Boston-area wastewater over the past week.
According to the CDC, wastewater testing should not replace existing COVID-19 surveillance programs, but is meant to complement them by providing trend data when timely clinical testing is underutilized or inaccessible. By testing wastewater frequently, the metric can be a leading indicator of COVID-19 prevalence in a community.
However, the CDC does caution that “it is not possible to reliably and accurately predict the number of infected individuals in a community based on sewage testing.”
Last week Gov. Baker deployed two members of the Massachusetts National Guard to Nantucket Cottage Hospital – part of a statewide deployment of more than 500 service members – to assist with hospital staffing shortages and the surge of COVID-19 cases across the state.
Watch the latest joint video update on Nantucket’s COVID-19 status from Nantucket Cottage Hospital and the Nantucket Health Department (Dec. 21, 2021) :
