This is a work in progress! I only published it so that I could show someone else one of the charts. IGNORE!
Transmission
☀️ There’s some interesting evidence that sunlight reduces influenza and COVID-19 susceptibility or transmissibility.
☀️ This older paper using data from New York (2018-02) reports that amount of sunlight correlates with influenza peaks. One particular surprise to me was that the fall of 2009 had unusually low sunlight levels in New York counties, and that corresponded to a very early flu season. @@@ read more carefully
☀️ This paper with data from USA, Italy, and UK (2021-08-01) reports that the mortality rate ratio drops by 32% per 100 kJ per m2 increase in mean daily UVA.
☀️ This paper (2021-01-21) on COVID-19 seasonality pointed out that although one reason given for wintertime influenza surges is holiday gatherings — Christmas, Hannukkah, and New Year’s — yet there was no peak in Australia around those times. Australia’s peaks during this time were in their winter, our summer, so nowhere near “holiday gatherings”.
You might guess that the issue is temperature, but they found only a slight relationship between temperature and the date of the influenza peak, and zero relationship between humidity and the date of the influenza peak. They did, however, find a very strong correlation between latitude and the date of the influenza peak! The peak was generally about three weeks after the shortest day of the year.
This comment on Stack Overflow (edited 2021-04-01) draws a graph of latitude vs. UV level, which looks uncorrelated:
However, there are other elements of sunlight.
This paper (2022-09) theorizes that it’s near-infrared radiation. @@@covidbc_2loez7
This paper (2023-01-19) backs up the connection between the percentage of overweight adults and @@@
Note: since the first paper came out, the COVID-19 waves have moved around a lot, with BC having as many October or April waves as “holiday” waves. However, influenza waves are (still) almost always during the dark days of the year. With the exception of a strange flu positivity year for Australia in 2018, Canada and Australia are pretty much shifted by six months:
The US and South Africa is even more obviously opposites:
This paper using data from UK and Finland (2026-02-09) reports that obese people are more susceptible to infectious diseases and other pathogens. @@@
Treatments
This paper from Italy (1997) suggests that NAC is a good prophylactic for influenza @@@