BOSTON—At a sewage treatment plant on a sliver of land in Boston Harbor, trickles of wastewater are pumped into a plastic jug every 15 minutes. Samples from the jugs, analyzed at a lab in nearby Cambridge, Mass., are part of the growing effort to monitor the Covid-19 virus in wastewater across the U.S.
On Deer Island in Boston, readings from the system covering 2.4 million people have recently shown virus readings leveling off after a steep decline from this winter’s Omicron-driven rise. In some areas, levels of the virus may be edging higher.