Data insight

COVID waves: Brazil and US compared

The timing of waves may be dissimilar, but their mortality impact and regional diversity are not

These visualizations highlight the contrasts of different COVID waves between Brazil and the US by region: the 4 Census Bureau regions for the US and the 5 IBGE regions for Brazil. The values are stacked and should be read as contributions to the total case rate at the national level.

Differences in geographic location mean that we would expect COVID waves in the Northern and Southern Hemispheres to be less synchronized. The variation of the season matters. The fact that the US is in the Northern Hemisphere and (much of) Brazil in the Southern Hemisphere with a significant part of the country around the Equator will matter. 

The comparison is still relevant to assess the amplitude of successive waves and the contribution of regions to the national total. Let’s turn first to cases and then deaths due to COVID-19. 

The chart above shows partly confirms the pattern of winter waves being more severe than summer ones. The Northern Hemisphere winter led to high case rates in the US starting end-2020. Conversely, the winter in the Southern Hemisphere led to high case rates in Brazil June 2021 onwards. 

But we do see important deviations from this pattern. The period starting March 2021 in Brazil was one that marked the beginning of a rapid rise in cases. Similarly, the recent spike in cases in the US associated with the spread of delta did not occur during the winter season.

Given the intricacies of comparing case rates across hemispheres, let’s also compare across waves over the entire course of the pandemic. Both countries spent similar amounts of time in a zone when weekly case rates were above 2,000 per million. The spikes in the US however seemed more severe. 

That conclusion derives from the reported data. We know of course that reported case numbers may deviate considerably from actual underlying infections. That’s true for any country and differences in testing practices across countries and over time will have an important bearing on the assessment of the extent of the spread. Data limitations on testing in Brazil however complicate an analysis of testing. 

Regions contribute differently to the national total. They do because of their different sizes and their different performances in terms of regional case rates. In the US we see strong contributions from the South and West regions. In Brazil, the Southeast played a major role.

 

The picture on the mortality impact is completely different: the US saw higher peaks on case rates, but Brazil saw the highest spikes for death rates. Weekly death rates remained above 50 per million for a period from March till July 2021 and went well above the maximum seen in the US. 

Also here testing differences would matter and excess death estimates would complement the assessment. However, in cumulative terms we do not see dramatic differences in reported excess death rates between Brazil and the US. Excess death estimates confirm the remarkable similarity in cumulative death rates (260 per 100,000 for the US and 310 for the US as of mid-Sep 2021). Note that the discrepancy between estimated cumulative excess death rates and reported cumulative COVID death rates is actually considerably greater in the US than Brazil (about 12% in the US and 30% in Brazil as of mid-September 2021).

 

 

Finally, the regional diversity within the US and Brazil comes out even more starkly in the mortality data. In the US the Northeast dominated the stats early on in the pandemic but soon after the especially the South took over. In Brazil, the mortality toll is predominantly driven by the Southeast and to a lesser extent by the South and other regions.

 

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