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Dr Zoë Hyde Profile picture
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1 Jan, 6 tweets, 2 min read
Concerning new UK data show protection against hospitalisation is greatly reduced for the omicron variant. About 6 months after 2 doses, effectiveness is reduced to 52%.

Note this is a combined analysis of all vaccines - some may be higher, some lower.
assets.publishing.service.gov.uk/government/upl…
The good news is that a third vaccine dose brings protection against hospitalisation up to 88% for the omicron variant.

Protection against hospitalisation caused by the delta variant remains at a very high level, for both two and three doses.
A study from South Africa recently estimated that two doses of the Pfizer-BNT vaccine offers 93% protection against hospitalisation caused by the delta variant, and 70% for the omicron variant.
nejm.org/doi/full/10.10…
Going back to the UK data, remember that the estimate was for all vaccines combined (because they had insufficient data to analyse each vaccine separately).

Their combined estimate of 52% suggests the AstraZeneca vaccine might offer less protection than this figure.
This would be consistent with early attempts to estimate vaccine effectiveness.

After 6 months, protection against severe disease caused by the omicron variant was previously estimated to be:

AstraZeneca: 37%
Pfizer-BNT: 71%
Moderna: 81%
🔑 The key take-home message is getting a third vaccine dose is essential to have good protection against hospitalisation, especially for AZ recipients.

🔑 It also reinforces the importance of improving ventilation & wearing a good quality mask (KF94, FFP2/P2, N95) to stay safe.

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More from @DrZoeHyde

Dr Zoë Hyde Profile picture
30 Dec 21
The omicron variant is NOT mild.

Hospitalisations are 40-45% less likely than with the delta variant (imperial.ac.uk/mrc-global-inf…), but the delta variant is >2x more severe than the original strain (cmaj.ca/content/193/42…).

The omicron variant is AT LEAST as bad as the 2020 virus.
But the omicron variant is far more transmissible, and our vaccines don’t work as well against it.

This means that an omicron variant epidemic will infect far more people than a delta variant epidemic would.
In practical terms, this means the omicron variant is MORE dangerous than the delta variant.

I modelled what would happen if either of these variants were allowed to spread in Western Australia with only a *double-dose* vaccination level of 90% (i.e., hardly any third doses).
Read 6 tweets
Dr Zoë Hyde Profile picture
20 Dec 21
I recently went to two Christmas parties. Not a single person was wearing a mask.

And it was okay, because there’s no epidemic where I live. Western Australia has managed to sustain zero COVID for nearly 2 years.

Eliminating COVID-19 was always possible. The world chose not to.
This got people talking. Good. But the point isn’t Christmas parties or Western Australia. It’s that elimination is the only long-term strategy for ending the pandemic. I’m not someone who typically praises China, but the government there understood this.
bmj.com/content/375/bm…
But elimination doesn’t require draconian measures. There are many tools in the toolbox that we’re not yet using (or not using widely), such as ensuring everyone has a better mask. People need masks that can block aerosols. Better ventilation is also key.
masks4all.co/faqs-on-better…
Read 4 tweets
Dr Zoë Hyde Profile picture
8 Dec 21
I won’t sugar-coat things. This is a disaster.

People vaccinated with 2 doses of the Pfizer-BNT vaccine likely have no protection against infection with the omicron strain. Protection after 3 doses has likely taken a big hit as well.

What it means for severe disease is unclear.
There are similar data from South Africa.

Antibodies collected from people vaccinated with 2 doses of the Pfizer-BNT vaccine fare poorly against the omicron variant, although vaccinated people with a previous infection fared better.

But getting infected still isn’t a good idea! Image
The key question now, is what this means for protection against severe disease.

It’s unlikely to have been lost, but some reduction seems inevitable, particularly for those vaccinated with only 2 doses.
Read 10 tweets
Dr Zoë Hyde Profile picture
18 Nov 21
A study analysing the health records of people with COVID-19 has found that those who were taking SSRI antidepressants were less likely to die from the virus.

There was an 8% reduction for any SSRI, 28% for fluoxetine, & 26% for fluoxetine or fluvoxamine.
jamanetwork.com/journals/jaman… Image
The researchers tried to match people taking antidepressants with a group of control patients, based on age, sex, ethnicity, and medical history.

However, this wasn’t a randomised controlled trial, and it’s possible that other unmeasured factors affected the results.
That said, it’s plausible that SSRI antidepressants do reduce the risk of dying from COVID-19, because they have both anti-viral and anti-inflammatory properties.
jamanetwork.com/journals/jaman…
Read 4 tweets
Dr Zoë Hyde Profile picture
24 Oct 21
The AY.33 sub-lineage of the delta variant might not be readily detectable with current PCR or rapid antigen tests. These can be updated, but in the interim, cases may go undetected.

This is one reason why Australia’s plan to end hotel or home quarantine is premature.
This isn’t the first time variants have caused testing issues. One of the reasons the alpha variant was noticed was because tests for the spike gene returned false negatives.

Fortunately, the tests also looked for other parts of the virus, which had not changed significantly.
A variant also emerged in France that was difficult to detect. Viral loads in the upper (but not lower) respiratory tract were often below the detectable limit in people infected with the B.1.616 variant.
medrxiv.org/content/10.110…
Read 4 tweets
Dr Zoë Hyde Profile picture
23 Oct 21
Do you know what’s really funny? I’ve published more on geriatrics than @DrKGregorevic.

And while *I* have published papers on cognitive impairment and dementia, I can’t find a single paper on that subject by Dr Gregorevic in PubMed.
For example, not long ago, I published:

Incidence and predictors of cognitive impairment and dementia in Aboriginal Australians: A follow-up study of 5 years
alz-journals.onlinelibrary.wiley.com/doi/10.1016/j.…

And one of the projects I’m currently working on is a cluster RCT to improve dementia detection.
It’s interesting that when people don’t like me talking about the science of COVID-19, they resort to using ad hominem attacks.

And not particularly good ones, either.
Read 4 tweets

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