A new preprint study funded by the UK Government’s Department of Health and Social Care that used data from over 50,000 COVID-19 contacts has found that vaccinated people are “less infectious EVEN with Delta, and EVEN if CT count is the same” as well as finding that “kids appear less infectious and less susceptible, including with Delta”:
The study we've all been waiting for
Using data from >50,000 #COVID19 contacts, vaccinated people are less infectious EVEN with Delta, and EVEN if CT count is the same
Also, kids appear less infectious and less susceptible, including with Delta
— Alasdair Munro (@apsmunro) September 30, 2021
Data here:
The effects of vaccination on reducing infectiousness are strongest earlier on and wane slightly with time
Somewhat less effective for Delta than Alpha
Effects on reducing susceptibility to infection appear stronger and remain quite well preserved, with some waning
— Alasdair Munro (@apsmunro) September 30, 2021
The study also found that the age of the vaccinated person matters:
Data also clearly shows an age dependent effect
-Much lower rates of secondary infection from child index cases
-Mower secondary infection in child contactsThis remains true across settings including education, except "Events / activities" (?nature of contact)
— Alasdair Munro (@apsmunro) September 30, 2021
Recommended
We can cancel the panic now over breakthrough infections:
Importantly, adjusting for differences in CT count did not explain differences in rates of transmission between vaccinated and unvaccinated individuals
Using CT as a proxy for infectiousness in vaccinated vs unvaccinated will OVERESTIMATE how infectious vaccinated people are
— Alasdair Munro (@apsmunro) September 30, 2021
But it did find Delta more infectious than Alpha:
Interestingly, given equivalent CT counts at the higher end (lower VL) people with Delta are more infectious than with Alpha
This suggests the virus itself is more infectious, not just as a factor of viral load dynamics
— Alasdair Munro (@apsmunro) September 30, 2021
Methodology here:
This is contact tracing data including those who were tested by PCR within 1 – 10d of the index case testing positive
It is possible cases were missed – however this is unlikely to effect the proportions significantly as the denominator is those "tested" not those "exposed"
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— Alasdair Munro (@apsmunro) September 30, 2021
And, in conclusion, “we can finally put to bed the myth that vaccinated people are just as infectious as unvaccinated infected with Delta”:
We can finally put to bed the myth that vaccinated people are just as infectious as unvaccinated infected with Delta
Also good evidence of children being less infectious and less susceptible
Great study with very important results
7/
— Alasdair Munro (@apsmunro) September 30, 2021
But the CDC has some explaining to do:
Common sense told you that Wallensky and a politicized CDC renewed #Covid panic this summer baselessly. Now you're seeing data that proves it. https://t.co/U2TVl7WbpF
— Barry Gadbois (@BarryGadbois) September 30, 2021
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