First Massachusetts Case of South African Variant Detected in Cambridge


A Cambridge woman in her 20s became the first person in Massachusetts to test positive for the Covid-19 variant originally detected in South Africa, the city’s public health department announced last Thursday.

The woman tested positive for the variant — officially designated the B.1.351 variant — in January and isolated after the positive test, according to the health department statement. There are no known contacts or travel history related to the case. A second Massachusetts case of the variant from South Africa was detected on Feb. 19.

Detection of the variant takes several weeks to process after a result comes back as positive. The variant was confirmed with genetic sequencing by the Broad Institute of MIT and Harvard, according to a release from the Massachusetts Department of Public Health. The Broad Institute also processes Covid-19 tests for Harvard affiliates, which detects the presence of known Covid-19 variants.

“Detection of the B.1.351 COVID-19 variant is testament to the strength of our communicable disease surveillance system in the Commonwealth,” Cambridge Chief Public Health Officer Claude A. Jacob said in a press release. “It is also a reminder that this pandemic is far from over, and we all must continue to wear masks, social distance, and get vaccinated when it is our turn.”


Centers for Disease Control and Prevention guidance states the variant from South Africa spreads more easily than the original strain, as does the variant from the U.K. In its last update on Feb. 17, the Massachusetts Department of Public Health confirmed 44 cases of the variant from the U.K. in the state. Currently, there are no confirmed cases of the variant from Brazil.

Since Covid-19 tests target specific viral genes, mutations in the virus may bypass tests targeting only one genetic location. In late January, Broad Institute upgraded its testing, adding a second genetic target to its tests, helping Broad identify unknown Covid-19 variants, according to Broad Institute spokesperson Karen Zusi.

“One of several advantages of adding a second genetic target to the test is to help guard against new, unknown variants of the virus that could affect the performance of the assay, as well as increasing the sensitivity of the test,” Zusi wrote in an emailed statement.

Zusi added the Broad Institute has not adjusted its PCR cycle threshold for tests, meaning that tests still return a negative test result after viral RNA is not detected during the process.

While the PCR test administered to students at the College cannot identify which specific variant a person is carrying, the test detects the presence of known variants, Zusi wrote. Still, an “inconclusive” result should not be interpreted as a signal towards a positive or a negative result.

In an emailed statement, Harvard University Health Services spokesperson Michael Perry wrote that HUHS was keeping close track of variant-related news and urged Harvard affiliates on campus to continue safe practices.

“HUHS, like every other health care organization, continues to closely monitor the status of the pandemic, including information regarding variants of the virus,” Perry wrote. “The presence of variants in the broader community underscores the critical importance of continued masking, distancing and handwashing, and other relevant practices and protocols that have helped us limit the transmission of COVID-19 on campus.”

—Staff writer Claire H. Guo can be reached at Follow her on Twitter @clairehguo.

—Staff writer Christine Mui can be reached at Follow her on Twitter @MuiChristine.