Reports of influenza and a host of other infectious diseases have plummeted as the COVID-19 pandemic has driven people into lockdowns.

In many places, social distancing measures aimed at curbing the spread of the new coronavirus may be smothering the spread of other infectious diseases at the same time. But, in other places, the pandemic may simply be masking disease spread, as people may avoid seeking care for more routine infections while health care systems stretched thin by the pandemic may struggle to conduct routine, surveillance, testing, and reporting.

Some of the resulting declines are dramatic. Countries across the Southern Hemisphere have reported much lower numbers of influenza than usual. Australia, for instance, began 2020 with a relatively high level of flu—reporting around 7,000 lab-confirmed cases in both January and February. But the outbreak crashed in March, with reports of only 229 cases in April, compared with nearly 19,000 in April 2019, as noted by the New Scientist.

In Argentina, laboratory-confirmed cases of flu tallied between January and July was 64 percent lower than the average from the previous five years, according to a report by The Wall Street Journal. In New Zealand, which has been extraordinarily successful at controlling the COVID-19 pandemic, health officials reported that only 0.7 percent of the population had flu-like symptoms in the first week of July, while usual rates are around 3 percent to 4 percent. Brazil—which, in contrast, has struggled to control the pandemic—saw flu cases fall about 40 percent from usual.

Disease downers

In a recent report, the World Health Organization noted that flu activity was at “lower levels than expected,” but it noted that the data should be “interpreted with caution,” because the lower levels could be due to less disease and less reporting of disease.

But, influenza isn’t the only disease on the decline. A report by Reuters noted that cases of measles and mumps in China fell 70 percent and 90 percent, respectively, while the country was in lockdown. Likewise, countries in the Southern Hemisphere have seen declines in other viral diseases, such as respiratory syncytial virus and pneumococcal disease.

It’s still unclear if these global trends bode well for the United States, which is still facing high levels of COVID-19 spread as it heads into the fall flu season. The burden of disease may depend on whether Americans nationwide adhere to measures for social distancing, hygiene, and mask use.

In an interview earlier this month, CDC director Robert Redfield was pessimistic. “I am worried, he said. “I do think the fall and the winter of 2020 and 2021 are going to be probably one of the most difficult times we’ve experienced in American public health.”

https://arstechnica.com/?p=1695749