The Science indicates that even 2 meters may not be enough
unless you wear
a face mask.
Covid19 transmission and immunity
International Journal of Environmental Research and Public
Health —
Open Access Journal
Airborne Transmission Route
of COVID-19: Why 2 Meters/6 Feet of Inter-Personal Distance Could Not Be Enough
The COVID-19 pandemic caused the shutdown of entire nations
all over the world. In addition to mobility restrictions of people, the World
Health Organization and the Governments have prescribed maintaining an
inter-personal distance of 1.5 or 2 m (about 6 feet) from each other in order
to minimize the risk of contagion through the droplets that we usually
disseminate around us from nose and mouth. However, recently published studies
support the hypothesis of virus transmission over a distance of 2 m from an
infected person. Researchers have proved the higher aerosol and surface
stability of SARS-COV-2 as compared with SARS-COV-1 (with the virus remaining
viable and infectious in aerosol for hours) and that airborne transmission of
SARS-CoV can occur besides close-distance contacts. Indeed, there is reasonable
evidence about the possibility of SARS-COV-2 airborne transmission due to its
persistence into aerosol droplets in a viable and infectious form. Based on the available knowledge and
epidemiological observations, it is plausible that small particles containing
the virus may diffuse in indoor environments covering distances up to 10 m from
the emission sources, thus representing a kind of aerosol transmission.
On-field studies carried out inside Wuhan Hospitals showed the presence of
SARS-COV-2 RNA in air samples collected in the hospitals and also in the
surroundings, leading to the conclusion that the airborne route has to be
considered an important pathway for viral diffusion. Similar findings are
reported in analyses concerning air samples collected at the Nebraska University
Hospital . On March 16th,
we have released a Position Paper emphasizing the airborne route as a possible
additional factor for interpreting the anomalous COVID-19 outbreaks in northern
Italy , ranked as one of the
most polluted areas in Europe and
characterized by high particulate matter (PM) concentrations. The available
information on the SARS-COV-2 spreading supports the hypothesis of airborne
diffusion of infected droplets from person to person at a distance greater than
two meters (6 feet). The inter-personal
distance of 2 m can be reasonably considered as an effective protection only if
everybody wears face masks in daily life activities.
It is
not known how long immunity will last. But booster shots and yearly flu shots
are examples
of
dealing with this issue.
Can You Catch Covid-19 Twice?
Most scientists say
patients gain some immunity to the virus after the first infection
By
o
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o Months
into the pandemic, the scientific community’s understanding of Covid-19, the
illness caused by the new coronavirus, is rapidly evolving. New reports of
patients testing positive, or appearing to suffer symptoms after initial diagnosis, continues to generate concern that people who have had
Covid-19 are getting infected anew.
Here
is the latest on what we know, and don’t know, about the possibility of
becoming sick with the virus more than once.
I
recently recovered from Covid-19. Does that mean I can’t get it again?
Most
scientists say that people who have had Covid-19 gain some immunity to the
virus that causes it. What they don’t know is whether that protection lasts a
few months, a few years or a lifetime.
What
factors affect immunity?
The
immune system wards off infections by producing antibodies that
fight invaders. A range of hereditary and environmental factors, including diet
and sleep patterns, typically affect the strength and longevity of those defenses.
Immunity
also depends on the pathogen. For example, infection by the virus that causes
measles confers lifelong immunity. Others, like the influenza virus, can mutate
so rapidly that protective antibodies might not recognize them during a reinfection.
The
novel coronavirus mutates more slowly than the influenza virus. That gives
researchers hope that any natural immunity, or vaccine, would offer more
lasting protection. Even if someone gets sick again, researchers believe a
second infection might be milder than the first.
How
soon would my body produce antibodies to fight the novel coronavirus after an
initial infection?
The
U.S. Centers for Disease Control and Prevention says antibodies develop within
one to three weeks after infection.
A
study involving 34 hospitalized cases in China found that two patients, both
in their 80s, produced antibodies within three days of symptom onset. The rest
produced them two weeks after symptoms first surfaced. The findings were vetted
by other experts and published in an academic journal in March.
Is
there any good news?
A
group of Chinese researchers reported this month that they had infected six
rhesus macaques, allowed them to recover and then reinfected four of them 28
days after the first infection. None became sick again, showing their immune
system shielded them from a second infection.
The research, published in Science, says, however, that more studies are needed to understand whether the immune system can shield individuals from reinfection over longer periods of time.