COVID on the brain 🧠

Stroke like brain injury can be a life altering complication of SARS-COV-2 infection

Let's see how often is happens, what it looks like, and why.

A retrospective study was done in my own hospital trust :)

3,403 PCR+ COVID inpatients between March and May 2020

167 had neurological symptoms warranting neuroimaging

38 revealed vascular (ischemic or haemorrhagic) abnormality = 1.12% of total C19 inpatients

Mean age 59.7

Onset of neuro symptoms mean 10.1 days from admission

Even w/out COVID, many patients admitted for other reasons have strokes. However, in this COVID patient cohort when age adjusted the rate is ~5x ⬆️

87 vs 16 per 1000 hospitalised inpatients annualised rate

What do these look like on brain MRI:

- microhaemorrhages (commonest)
- watershed white matter hyperintensities
- susceptibility changes on SWI in superficial veins
- hypoxic-ischaemic changes

MRI features continued:

- parenchymal and subarachnoid haemorrhage
- acute and subacute infarct
- acute haemorrhagic necrotising encephalopathy (PRES)
- ADEM like changes

CT findings:

- Acute and subacute infarcts
- basal ganglia haemorrhage
- subarachnoid haemorrhage


- pro-inflammatory cytokine storm (IL-6, TNF-a)

- blood-brain and blood-CSF barrier dysfunction

- direct neuroinflammation

-micro vascular disruption of endothelium = extravasation of RBC/microhaemorrhages

- inflammatory neutrophil extracellular trap= thrombus

Although our hospital did not see a case of central venous sinus thrombosis (CVST), there is evidence of association/higher event rate with COVID👇

(same pathophysiology as presented above)

Typical background rate is 2-15 per million per year.

So in a country with high COVID prevalence the expectation will be CVST rate will be higher than typical year. Temporal association with a vax may be incidental to recent or new infection etc.

So more care than usual has to be taken to disentangle


Likely preventing ~120 severe hospitalised COVID cases stops 1 cerebrovascular event.

V consequential as can be permanently debilitating, life shortening or threatening.

Even compared to 'possible' CVST 🇩🇪 AZ vax saves an order of magnitude more from neurological events

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More from @DevanSinha

5 Mar
Temperature and SARS-COV-2 transmission:

Some seasonality expected for resp viruses, hard to say how much. England had unique circumstance Feb 7-13th.

- week long cold snap across country of similar magnitude
- no change in restrictions
- no increase in daily mobility

Due to variables being reasonably controlled we can estimate how temperature may affect general transmission dynamics.

Note Seasonality: viruses transmit at ALL times of year but climate affects biology and behaviour which impacts on how much transmission occurs.

Cases by specimen date in England showed a marked deceleration in the rate of decline the week after the cold period. From more than -5% per day to less than -2%.

(daily change adjusted for day of the week effect in testing)

Read 14 tweets
31 Dec 20
The AZ/oxford vac shows high immunogenicity and efficacy when delayed to 12 weeks for 2nd dose. Ab titres highest for 12 weeks 👇

BUT the delay for Pfizer vac though potential large societal benefits is definitely a risk...

🧵 1/
1. Pfizer efficacy was only trialled at 21 days for 2nd dose. (cf AZ/Ox 4-26 weeks)

2. This can be estimated at ~80-90% for 10-22 days after 1st dose


But Ab tires don't increase until 2nd dose for Pfizer, especially in the older age cohort who are the priority vaccine targets. How much protection are we giving them?👇

The 86% is a pooled estimate of all ages with younger population dominating.

Read 8 tweets
30 Dec 20
Disentangling Astra/Oxford vaccine data (it's a messy trial/ data presentation):

Efficacy after 1st dose overall: 52.69% (95%CI 40.52-62.37)
108 v 227 cases/10k cohorts

Subgroup analysis from 3 weeks after 1st dose until 2nd dose or 12 weeks: 73.00% (48.79-85.76)
12 v 44/8k

Overall vaccine efficacy with 2 completed doses: 70.42% (95%CI 58.84-80.63)
30 v 101 cases/5.8k cohorts

0 hospitalised and 0 severe disease in full vaccine cohort

For 1 dose subgroup only 2 hospitalisations (day 1 and 10 post vaccine when no immunity conferred), 0 severe

The trial is limited by the variability in administration of the second dose between 4 to 26 weeks.

Higher antibody titres were seen when delaying 2nd dose to 12 weeks

Only 5.9% of trial were over 65, and they tended to be in the early 2nd dose category

Read 5 tweets

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