Why viral infection intensity varies?

कोई भी बीजके अंकुरण के लिए आवश्यक है वातावरण | योग्य वातावरण के अभावमें बीज अंकुरित नहीं होगा | वायरसका भी ऐसा ही है | कोई भी रोगका आगमन मंदाग्नि से होता है | अग्नि मंद\विषम\तीक्ष्ण होने पर दोष विकृत होते है और व्याधि का आगमन!

Seeds require conducive environment.

Infection requires receptors and co-factors.

An interesting additional finding of the study was that the ACE2 receptor density on the cells increased with age and was generally higher in men than in women. [0]

So, the virus is selective in manner of choosing its host.

Numbers emerging from India and US cases suggest that, more and more millennials are getting affected. [1][2]

Is it because our next generation is aging fast? Is it because millennials turn sexually active far earlier than expected? (The protein and mRNA expression of ACE2 in the testes is almost the highest in the body[3][4]). Raising the questions. Not concluding it. It is important area of research.

[0] https://www.bihealth.org/en/notices/what-cells-does-the-novel-coronavirus-attack/

[1] Now, new data out of the U.S. Centers for Disease Control and Prevention (CDC) have thrust younger adults into an even brighter spotlight: it suggests adults ages 20 to 44 have accounted for nearly 30% of U.S. COVID-19 cases, and 20% of related hospitalizations. After adding adults ages 45 to 54, the percentages swelled to nearly 50% and 40%, respectively. https://time.com/5806475/covid-19-millennials/

[2] https://www.livemint.com/news/india/covid-19-going-against-trend-most-patients-in-india-are-millennials-11586000044825.html

[3] ACE2 Expression in Kidney and Testis May Cause Kidney and Testis Damage After 2019-nCoV Infection https://www.medrxiv.org/content/10.1101/2020.02.12.20022418v1.full.pdf

[4] Effect of SARS-CoV-2 infection upon male gonadal function: A single centerbased study https://www.medrxiv.org/content/10.1101/2020.03.21.20037267v1.full.pdf

Why just cow milk? Microbes differs by milk

Why feet stinks? To protect you!