Many countries are asking for proof of vax, or testing to travel
I don’t understand this. Vax work Well to stop disease…
But it’s time to clarify they do not stop transmission. They slow it down
But it simply is not appropriate to assume that vax = not infectious
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If we don’t appreciate this soon immediately, then we will see irresponsible policy that allows the virus to keep on spreading.
This is almost certainly even more true for Omicron which, if anything, will spread more efficiently, not less, than other variants among vax’d
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We can be fully transparent about what vaccines do very well (protect you!) and what they are not doing very well (stopping transmission) while still advocating for everyone to be vaccinated
Most ppl see this and any lack of transparency harms vaccine uptake even more.
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So what should we do for travel and to limit spread?
KNOW BEFORE YOU GO
KNOW AFTER YOU ARRIVE
Knowledge here is the power to not inadvertently spread the virus.
It is empowering!
There are few better ways to not spread to others than knowing you are infectious!
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International travel can and should continue through this pandemic. Border closures can be devastating with consequences far beyond the virus itself.
But it should be done with confidence.
Test hours before travel, Test daily for 5-7 days each AM after arrival.
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Rapid testing need not be performed on the honor system - And for travel, it should not.
Travel sometimes does & should use verified testing platforms. (I’m now CSO of one - @eMedCertified - and I’m proud to be helping create these needed tools that can keep borders open)
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In case there is any confusion, this thread is in full support of vaccination - and should not be construed as anything but 1000% support.
It is also in support of clear strategy and using each tool in our toolbox to its fullest, and know the limitations of each.
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This from @CDCgov is exactly why Rapid tests are important!
A PCR 2 days before an event, flight or (fill in blank) does NOT reflect you today
2 days ago can be neg but you can be a superspreader now
A rapid test used just before the event is always best.
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Its remarkable & contradictory that while CDC makes this figure 👆showing that neg tests 3 days before do not mean you’re negative on thanksgiving… while still recommending testing 2-3 days before travel.
The safest approach is to recommend a rapid test hours before travel
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In the midst of Omicron, instead of border lockdowns, we can use rapid tests just before a flight. Could even consider a PCR 24-48 hrs before amd a rapid test just a couple hours prior to flight.
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Monitoring wastewater for viral load estimates outbreak size
In just a few weeks, in Pretoria S. Africa (north of Johannesburg) viral load detected in wastewater has reached similar levels as the peak of Delta
This at least indicates that transmission may be remarkably swift
More information on this metric can be found here.
IMO this offers a fairly unbiased view into viral load at a population level which, barring major changes in the viral loads within individuals, can be extrapolated to an extent to cases or prevalence across a population.
🧵 Why some vaccines stop transmission & others don’t:
Vaccines that stop transmission are often against viruses that replicate internally first and only then transmit (like measles). So if the vaccine stops internal replication, it stops transmission.
For COVID vaccines…
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For vax against upper respiratory viruses like SARS2, these viruses often don’t require “internal” replication. They just land in the nose, replicate locally & transmit on. So the vax can block “internal” replication and thus stop disease separate from stopping transmission
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The immune response in the upper respiratory tract is somewhat distinct from response in lungs, blood, lymph, etc.
Most vaccines create a multitude of layers of protection that can block a pathogen in lungs, blood, lymph, without offering the same in the nose/mouth/throat
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