9/21—COVID-19 likely spreading from people to animals—and vice versa
Three new studies suggest that high proportions of cats and dogs may have acquired COVID-19 from their owners and that the virus jumped back and forth between humans and minks on farms in the Netherlands (CIDRAP News, 2020).
A laboratory-based study examining the properties of silk fabric to evaluate its potential as a protective barrier for personal protective equipment and as a functional material for face coverings during the COVID-19 pandemic
We examined the hydrophobicity of fabrics (cotton, polyester, silk). Silk was more effective at impeding the penetration and absorption of droplets due to its greater hydrophobicity relative to other tested fabrics. We show that silk is a hydrophobic barrier to droplets, can be more breathable than other fabrics that trap humidity, and are re-useable via cleaning.
Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 During Long Flight
We investigated a cluster of cases among passengers on a 10-hour commercial flight. Affected persons were passengers, crew, and their close contacts. We traced 217 passengers and crew. Among the 16 persons in whom SARS-CoV-2 infection was detected, 12 (75%) were passengers seated in business class along with the only symptomatic person (attack rate 62%). Seating proximity was strongly associated with increased infection risk (risk ratio 7.3, 95% CI 1.2–46.2). We found no strong evidence supporting alternative transmission scenarios.
In-Flight Transmission of Severe Acute Respiratory Syndrome Coronavirus 2
Four persons with severe acute respiratory syndrome coronavirus 2 infection had traveled on the same flight from Boston, Massachusetts, USA, to Hong Kong, China. Their virus genetic sequences are identical, unique, and belong to a clade not previously identified in Hong Kong, which strongly suggests that the virus can be transmitted during air travel.
A history of herd immunity
How did herd immunity enter the language of public health? The phrase seems to have first appeared in the work of American livestock veterinarians concerned about “contagious abortion”—epidemics of spontaneous miscarriage—in cattle and sheep. By the 1910s, it had become the leading contagious threat to cattle in the USA. Farmers destroyed or sold affected cows. Kansas veterinarian George Potter realised that this was the wrong approach. Writing with Adolph Eichhorn in 1916 in the Journal of the American Veterinary Medical Association, he envisioned “herd immunity”. As he wrote in 1918, “Abortion disease may be likened to a fire, which, if new fuel is not constantly added, soon dies down. Herd immunity is developed, therefore, by retaining the immune cows, raising the calves, and avoiding the introduction of foreign cattle.”
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