T cell response to vaccination: Work from University of Pennsylvania. Thread.

-CD4 T cell response includes Th1 and Tfh cells
-Th1 cells support & enhance memory CD8 T cell responses
-Tfh cells work on germinal centres, B cells & plasma cells

1/4

biorxiv.org/content/10.110…
-Vaccination induces T cell response which resembles natural infection

-All age groups has similar T cell response, unlike antibody response which may be lower with age

-Early CD4 response & gradual CD8 response is the norm

-This explains early protection after vaccine

2/4
-CD4 T cells can recognize 23 epitopes distributed throughout the spike protein (see Tweet)

-Only 4 of these epitopes could potentially be altered by the variants B.1.1.7 and B.1.351 (UK, South Africa)

-This means that protection by T cells is not affected much by variants

3/4
-Memory T cells generated could be:

1. EM (effector memory cells) that patrol the blood and peripheral tissues

or

2. CM (central memory cells) which are CCR7 positive and home efficiently to lymphoid tissue, where they lie in wait for a very long time.

4/4
Related tweet on why T cells attack the spike protein on multiple fronts that can't all be altered at the same time by variants

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More from @RajeevJayadevan

2 May
Did elections contribute to the COVID-19 surge? We are always tempted to say yes. I decided to do a comparison. Surprisingly, the graphs I obtained from election & non election states are near-identical. This suggests that the wave is a seasonal surge in a geographic region.
1/9 ImageImage
The two images represent election states (where big outdoor gatherings occurred) on the right, and comparable non election states on the left. I have included two sets of pictures. The names of the states are on the graph. If you compare the timelines, it is near-identical.

2/9
The question is whether the surge would have occurred anyway, by pattern, and maybe the large election rallies amplified it to an extent.

This virus behaves in a wave-like pattern in most nations. The reason for the steep upward slope is exponential increase.

3/9
Read 10 tweets
2 May
T cells work against variants & are not affected by E484K or N501Y mutation.

1 dose of vaccine is enough if past infection: the response was so amplified, it even covered the major variants B.1.351 & B.1.1.7. Note that vaccine is based on old virus.

1/5
science.sciencemag.org/content/early/…
But in naive patients, T cell response was lower with one dose of vaccine.

96% (22/23) of vaccinated post infection individuals made a T cell response to Spike protein, compared to 70% (16/23) of vaccinated naïve individuals.

2/5
After 1 dose, vaccination-naïve (no past infection) group attained similar antibody titers to the post infection group at 16–18 & 28–30 weeks.

The majority of SARS-CoV-2 immune naïve individuals made no nAb response to the B.1.1.7 (18/20) and B.1.351 (17/20) after 1 dose.

3/5
Read 5 tweets
2 May
“It is time for India’s policymakers to trust those with relevant expertise, to make sure the necessary data are collected and available, and to accept the value of scientific findings, even if they do not fit the government narrative”

writes @tvpadma

nature.com/articles/d4158…
One such warning we had made in January, based on experience, science and local data.
m.timesofindia.com/india/coronavi…
This warning was reported by The Hindu in January.

“Do not lower guard yet” read the headline.

thehindu.com/news/national/…
Read 4 tweets
17 Apr
B.1.617 variant is different from other named variants. The 2 mutations L452R & E484Q in the spike protein are unique.

There are a total of 15 mutations which also involve structural proteins, replication enzymes and non-structural proteins.

1/9

forbes.com/sites/williamh…
In the UK, this strain has been growing quickly, similar to B.1.1.7.

In India it has been found in MH, GJ areas. It represented 6% of the 2844 genomes submitted from India to GISAID since March 1.

Without more data, it is impossible to comment on its growth in India.

2/9
Although its mutations are consistent with immune escape (antibodies) and faster spread, proof is required.

At this time it is only a possibility that the B.1.617 mutant (also dubbed ‘double mutant’) has these abilities.

Also detected in Belgium, UK, NZ, Ireland etc.

3/9
Read 9 tweets
15 Apr
1: 1 million or 1:250,000 risk of clot from vaccine sounds scary for many.

Non-COVID comparison:
risk of death 1:5000, for women who become pregnant.(MMR)

In India it’s 1:900.

That’s the risk women accept when they plan pregnancy.

1/4
yahoo.com/news/dont-star… via @YahooNews
The risk of death for women who decide to become pregnant is 1:5000 in US, 1:900 in India (overall), 1:2000 in Kerala, India,1:546 in Zambia.

That is the risk all women knowingly or unknowingly accept when they plan pregnancy. (These data are from well before pandemic)

2/4
Low numeracy is a universal problem; when the human mind is unable to distinguish between different fractions or ratios.

Hence, the risk of vaccines is grossly exaggerated.

🔴 Let me list a few other risks below for comparison, to see how we perceive risk:

3/4
Read 4 tweets
12 Apr
AstraZeneca Vaccine and clots: this important paper from Germany proves that VITT is not the result of cross-reactivity between anti-spike antibodies and platelet factor 4 (PF4).

See thread and links below 👇

researchsquare.com/article/rs-404…
VITT is vaccine-induced thrombotic thrombocytopenia, an extremely rare and serious complication with low platelet count & unusual clot formation.

This is being extensively discussed in the context of AstraZeneca’s COVID vaccine.

This thread explains the research above.

1/n
The researchers’ findings also suggest that PF4 antibodies are likely an “innocent bystander” in many patients. In other words, their presence alone does not predict disease.

In fact, 9 of 10 COVID-19 patients who had thrombosis did not have PF4 antibodies.

2/n
Read 14 tweets

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