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Stefan Marciniak Profile picture
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18 Dec, 4 tweets, 1 min read
>35,000 new British cases yesterday

18,510 in hospital

Feeling for my colleagues on the wards this Christmas.
On the bright side

138,541 vaccinated

That’s 0.21% of the UK
But then again
bbc.co.uk/news/health-55…

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More from @Prof_Marciniak

Stefan Marciniak Profile picture
19 Dec
The new “Kent” strain of SARS-CoV-2 (officially named VUI 202012/01 for Variant Under Investigation, year 2020, month 12, variant 01) was identified as have multiple spike protein mutations

1/n Image
These include deletion 69-70, deletion 144-145, N501Y, A570D, D614G, P681H, T716I, S982A, D1118H

2/n
gisaid.org/references/gis…
Structural modelling suggests N501Y (orange in Fig) might affect host receptor and antibody binding

3/n
Credit gisaid.org/references/gis… Image
Read 18 tweets
Stefan Marciniak Profile picture
19 Dec
Great point

Sensitivity = proportion of actual cases (ppl with a disease) that a test picks up

99% sensitive means 99 out of 100 truly affected ppl will be detected.

1/n
What’s the “gold standard” to determine what is a true case?

It depends on the condition in question, but for a viral RT-PCR a range of concentrations of RNA or virus can be added to a negative sample to help determine the limit of detection

2/n
Specificity = proportion of unaffected ppl that a test correctly identifies as not having the disease

99% specific means 99 out of 100 truly unaffected ppl will be correctly labelled as being negative.

Many known negative samples will be examined to determine this value.

3/n
Read 10 tweets
Stefan Marciniak Profile picture
6 Dec
The Background

1860s: nucleic acids discovered
1940-50s: the concept that “DNA makes RNA makes protein” is developed (& is called the central dogma)
1960s: messenger RNA discovered

1/n
Path to the vaccine

1989: use of lipid nanoparticles to get mRNA into cells
1990: RNA injected into muscle can cause local synthesis of a protein
1994-9: RNA vaccines shown to induce immune response
2008-11: early phase trials

2/n
2003-2012: studies to generate a vaccine against 2 new severe coronavirus diseases SARS and MERS identify the spike protein as a good target for protective antibodies

3/n
Read 7 tweets
Stefan Marciniak Profile picture
5 Dec
How science works:

Observations are made.
A hypothesis is generated.
Experiments are performed to test (try to disprove) the hypothesis.
This cycle is repeated many many times until the experiments are unable to disprove the hypothesis.
The results are shared at talks or posters at conferences or as preprints, so others can comment & criticise.
The results are then published as papers (a gruelling process when the paper is assessed by tough anonymous scientists who point out every error, big or small, which must be corrected).
Afterwards, scientists try to reproduce those results to see if they’re real.
Read 6 tweets

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