Thread by @ashwinrajenesh

🧵
VE vs omicron
"Among those who had
received 2 doses of AstraZeneca, there was no effect against #Omicron (against symptomatic disease) from 20 weeks after the second dose."

That's among those who have completed their 2nd #COVISHIELD (AZ) dose before Aug 22nd of 2021.
(1/8)

#HCWs were vaccinated earliest in India, with majority completing their second dose of AZ as early as April 2021. (That's >35 weeks since 2nd dose)

They currently face greatest exposure risk as noted in many large outbreaks in hospitals and affect delivery of healthcare.
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At-risk population were vaccinated next in India, and so were the elderly. Vaccine efficacy has shown to have more profound immune waning in elderly individuals.

These populations are an urgent priority, to prevent severe disease & death (The 2x dose still does that well).
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The fall in VE against symptomatic disease with an Omicron variant #COVID19 infection goes back up (atleast temporarily) to around 60% following an mRNA #BoosterJab
(A 3rd AZ booster dose may induce similar cellular response as #mRNA vaccine, but less antibody boost)
(4/8)

The report shows increase in VE against hospitalization for Omicron to go up from 52% to 88% within 2 weeks after a 3rd dose (All vaccines, combined data).

That's a +36% reduced hospitalization with a 3rd dose. This will decrease pressure on the #healthcare infrastructure.
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Once again reminding you all, Omicron is not a #mild disease.
'Milder' than Delta, but will still cause significant illness and mortality among the at-risk #unvaccinated.
#LongCovid morbidity potential is unknown.
Indices lag, but will follow 👇🏽

https://twitter.com/ashwinrajenesh/status/1480319543041933313?t=8vQRSEGEbKwZjo0hYuadfg&s=19

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TLDR:
While VE may be lost against symptomatic disease with 2x doses of the AZ vaccine after ~ 5 months, it still retains excellent efficacy in preventing death & even severe disease.
A 3rd dose may boost the VE against symptomatic disease & hospitalization significantly.
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Data from the Technical briefing: Update on
hospitalisation and vaccine effectiveness
for Omicron VOC-21NOV-01 (B.1.1.529)
UK Health Security Agency @UKHSA
assets.publishing.service.gov.uk/government/upl…
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