On Fri, 16 Oct 2020 16:28:02 -0700, Bob F wrote:

On 10/16/2020 3:57 PM, Frank wrote:
On 10/16/2020 5:57 PM, Neill Massello wrote:
wrote:

Depending on who you believe, a vaccine may not be effective on this
virus. It all gets back to that immunity question.

If vaccines don't prove out, the best approach may be masks: reduce the
viral load received by those who do get infected, so that they can
develop immunity while going through a milder form of the illness.


I had wondered about that and you appear correct:

https://www.medpagetoday.com/infecti.../covid19/88692

As a chemist who worked with toxicologists I knew that toxicity was dose
related.* I know that viruses will replicate and wonder what dose might
be needed to assure replication.

No doubt that it is good to wear a mask.



That is a very good article.

"Cruise ship passengers who embarked from the coast of Argentina in
mid-March were unaware that they were living in a COVID-19 hotspot for
more than a week after the ship departed.

The reason why these passengers were oblivious? Because a majority of
the cruise ship's cases were asymptomatic.

Researchers are now pointing to this cruise ship outbreak, in which all
passengers were provided surgical masks, as evidence that universal
masking may result in a higher proportion of asymptomatic COVID-19
cases. Other outbreaks of mostly asymptomatic cases where widespread
masking was implemented, in places like jails and meatpacking plants,
provide epidemiological data that masks could reduce viral inoculum --
and as a result, decrease the severity of illness."

"
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A photo composition of a person wearing a mask, a cruise ship, and
coronaviruses

Cruise ship passengers who embarked from the coast of Argentina in
mid-March were unaware that they were living in a COVID-19 hotspot for
more than a week after the ship departed.

The reason why these passengers were oblivious? Because a majority of
the cruise ship's cases were asymptomatic.

Researchers are now pointing to this cruise ship outbreak, in which all
passengers were provided surgical masks, as evidence that universal
masking may result in a higher proportion of asymptomatic COVID-19
cases. Other outbreaks of mostly asymptomatic cases where widespread
masking was implemented, in places like jails and meatpacking plants,
provide epidemiological data that masks could reduce viral inoculum --
and as a result, decrease the severity of illness.

Writing in the New England Journal of Medicine, Monica Gandhi, MD, and
George Rutherford, MD, of the University of California in San Francisco,
hypothesized that widespread population masking may act as a sort of
"variolation," exposing individuals to a smaller amount of viral
particles and producing an immune response.

Gandhi told MedPage Today that the viral inoculum, or the initial dose
of virus that a patient takes in, is one likely determinant of ultimate
illness severity. That's separate from patients' subsequent viral load,
the level of replicating virus as measured by copies per mL.

The "variolation" hypothesis holds that, at some level, the inoculum
overwhelms the immune system, leading to serious illness. With less than
that (and the threshold may vary from one person to the next), the
individual successfully fights off the infection, with mild or no
clinical illness.

"Diseases in which your immune system has a big role to play in how sick
you get -- and your immune system contributes to pathogenesis -- do not
seem to be able to handle a large viral inoculum," Gandhi said in an
interview.

Severe COVID-19 may be caused by a reaction known as the cytokine storm,
an immune response in which the body attacks its own cells and tissues
as opposed to the virus itself. Although this theory has yet to be
proven (and other theories, such as the bradykinin storm, have been
suggested), a large initial dose of SARS-CoV-2 may be the trigger.

Trials that give humans different doses of viral RNA are not ethical, of
course. But animal studies provide preliminary evidence that viral
inoculum could impact disease severity, Gandhi noted. In a study of
Syrian hamsters, for example, those infected with a higher dose of
SARS-CoV-2 had worse outcomes compared to those infected with smaller
amounts of virus.

Masked hamsters were also shown to be less likely to get COVID-19
illness than those without masks, a separate study found. And if they
did acquire the illness, it was more mild.

"We know that a higher inoculum of an infectious agent generally makes
people sicker," said Peter Katona, MD, an infectious disease specialist
and professor at the University of California in Los Angeles."

Masked hamsters? I need photos. :-)