Record low influenza cases show how COVID-19 is more contagious and 'less forgiving,' experts say

Influenza cases hit a record low in 2020, according to CDC data. Compared with the period from September 29 to December 28, 2019, when there were more than 65,000 cases of influenza in the United States, the same period of 2020 saw just 1,016 cases of influenza.

Influenza cases hit a record low in 2020, according to CDC data. Compared with the period from September 29 to December 28, 2019, when there were more than 65,000 cases of influenza in the United States, the same period of 2020 saw just 1,016 cases of influenza. Health experts say that high vaccination rates against influenza—along with social distancing, mask wearing, and hand hygiene to stop the spread of SARS-CoV-2—were key factors. Public health labs, meanwhile, saw a significant increase in testing, with most checking for influenza A and B and the coronavirus. In the last quarter of 2020, there was slightly lower clinical lab testing, as doctors ordered fewer influenza tests because less of the illness was circulating. "The public health labs test for more surveillance purposes rather than patient care reasons and are therefore a better measure of influenza burden each season than clinical labs," noted CDC spokesperson Kate Grusich. While it is positive news for influenza containment, experts note the data says a lot about COVID-19's transmissibility. "It says that it's more contagious and that it's less forgiving of any lapses of these types of prevention measures," said David Hooper, MD, chief of the infection control unit at Massachusetts General Hospital. One reason COVID-19 is more transmissible, he said, is because people can shed the coronavirus days before showing any symptoms, if they even develop symptoms. Susan Rehm, MD, vice chair at the Cleveland Clinic's department of infectious diseases, also notes that whereas most people have some innate immunity from past influenza vaccinations and infections, "COVID is a novel infection caused by the SARS coronavirus, and no one has any innate immunity to it."