COVID-19 ISO Insights

Why Have Flu Cases in the Southern Hemisphere Dropped So Dramatically in 2020?

August 10, 2020

By: David Geller, CPCU, SCLA

Back in May, we posted about the close watch being kept on the Southern Hemisphere and how their influenza season would develop in the midst of the COVID-19 outbreak. Would social distancing help restrict the flu from spreading? If influenza was rampant, how would hospitals manage both COVID-19 patients and those with the flu? Will more residents choose to go to doctor’s offices and be vaccinated from the flu, or less?

The answers to these questions potentially could provide a window into what may lie ahead in the Northern Hemisphere for the flu season that typically begins in October (in the Southern Hemisphere, it generally begins in April). And it appears that some data is beginning to surface that indicates what may be to come in the North.

According to the Wall Street Journal, much to the relief of the medical community, the number of people who have been infected with the flu south of the Equator has plummeted compared to this time in 2019. Here are a few examples cited in the article, which was published in late July:

  • In the last two weeks of June, Australia recorded 85 new laboratory-confirmed influenza cases. In 2019? 22,047 were recorded in the same two weeks. Overall, from the beginning of January to June 30th, confirmed flu cases in Australia have plummeted 84% in 2020 (20,739) from 2019 (132,424).
  • Similarly, in Argentina, laboratory-confirmed flu cases dropped 64% in 2020 (151,189) from a five-year average of 420,737.
  • Some doctors in South Africa reportedly state that there were so few cases that the season epidemic technically hadn’t even begun.
  • Even in Brazil, where COVID-19 cases have been rampant, flu cases dropped by 40% and deaths resulting from the flu were halved in 2020.

In addition to a significant reduction in confirmed flu cases, respiratory viruses in general have been less frequent as well. For example, after Chile recorded 20,949 confirmed seasonal respiratory infections through the first half of 2019, only 1,134 of these infections have been logged in 2020.

There are various theories that different experts and analysts have pertaining to this significant drop-off. Per the WSJ:

  • The restriction of travel limited the number of people coming from the Northern Hemisphere during their flu season and infecting these regions as the weather cooled down around March, a development that, in a normal year, typically increases its rate of spread.
  • Efforts to stop the spread of COVID-19 (wearing masks, more hand washing, etc.) have served to limit the number of people infected with the flu or other respiratory illnesses.
  • The increased use of telemedicine has kept people away from germ-infested doctor’s offices that sometimes help facilitate the spread of these viruses.
  • One doctor commented to the WSJ that “‘children are the main reservoir’” of these viruses, and since they haven’t been at childcare, less spread across the community has ensued.

Perhaps relatedly, a New York Times article recently reported on a study which found that, like COVID-19, aerosol transmission of the seasonal flu may be a key driver of its spread. Therefore, the measures taken to thwart COVID-19 may also be working to quell the flu as well.

Lastly, different countries, such as Chile and Australia, have reported “far higher rates of vaccination than in previous years.”

Can These Developments be Used to Project How the Upcoming Flu Season Will Unfold in the United States?

There appears to be some mixed beliefs on this front. After all, many questions can’t really be answered at this time. Will travel restrictions in the Northern Hemisphere be as stringent in a few months as they were in countries in the Southern Hemisphere back in March and April? Will schools re-open, and if so, to what extent? Will efforts be made to re-open indoor dining and other functions during the Winter, even as COVID-19 likely continues to linger?

It may be too early to say. However, some scientists do tend to agree that a normal flu season could exacerbate the stresses on hospitals that COVID-19 is already applying.