Seasonality and lung infections: the case of Brazil.
Currently, the equatorial metropolis of Manaus is the hotspot for covid in Brazil.
In polar nations ie Canada, UK, seasonal variation in lung infections is marked, variations in Brazil are less

From the perspective of Brazil, Canada has relatively few pneumonia deaths, while central Africa (which is equatorial and has no winter to speak of) has the highest rate of pneumonia deaths.

If winter's cold air isn't the driver of pneumonia throughout much of the world, what is?
Here is a map of indoor air pollution-related deaths in the world. The attribution is coal and wood fires.

A respiratory infectious disease of concern is tuberculosis. Here are a variety of tuberculosis maps. Variance here, but southern Africa appears to be "hotspot." It does not appear to be more common in colder climates.

Back to Manaus for a moment, where apparently they have run out of oxygen tanks due to high numbers of covid cases. Their air quality appears to be good, as is the air quality of Brazil as a whole

Here is a map of tuberculosis in Brazil. Manaus is located in the state of Amazonas. Here we see that this state has the highest rate of tuberculosis in Brazil. Is there a relation between factors giving rise to TB and those giving rise to covid in Brazil?

Here is the covid map from end of April 2020. Note that Manaus district had the highest incidence in Brazil

Here is a climate map for Brazil. The Amazon district is notable for high humidity