COVID-19 Pandemic Update 101: T Cell Immunity vs. Antibodies & Prior Exposure to Other Coronaviruses

The relationship between antibodies for the novel coronavirus (SARS-CoV-2) and immunity, vaccine efficacy, and spread of COVID-19 has received significant attention. Dr. Seheult is back to illustrate why T cells have received less attention than antibodies, but may be more important to long term immunity from COVID-19. Dr. Seheult also discusses how previous infections with common coronaviruses may provide some immunity to SARS-CoV-2, and the hypothesis that reducing the inoculum (initial dose) of SARS-CoV-2 might result in less symptom severity (This video was recorded August 10, 2020).

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Roger Seheult, MD
Board Certified in Internal Medicine, Pulmonary Disease, Critical Care, and Sleep Medicine.
Associate Professor at the University of California, Riverside School of Medicine

Video Produced by Kyle Allred

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MedCram medical videos are for medical education and exam preparation, and NOT intended to replace recommendations from your doctor.
#COVID19 #SARSCoV2 #FOAMed

[Medcram]

Quick links to our recent previous COVID 19 updates:

[Skunkhunt_]

CHEERS to medcram for holding my hand for the past 5 months!

[BulldustHHH]

Now everyone wants to see the pictures of hamsters in masks.

[RussCR]

I think there is some confusion about the number of asymptomatic cases on the Diamond Princess cruise ship. From what I have read, the 47% figure comes from the percentage of infected individuals who had no symptoms at the time of testing. Statistical models were subsequently used to estimate the number who remained asymptomatic versus the number who were simply pre-symptomatic at the time of testing. The final percentage for true asymptomatic cases was estimated at just less than 20%.

[abdigure]

Thank you very much for the constant updates!

[maryprantephd]

Marvelous, as usual: Pertinent, organized, clear, concise. Thx so much! Glad to have you back, Dr S; hope you fully enjoyed your "time off"!

[makiph]

I’ve been watching your videos(mostly about COVID19) and learning a lot from them. Thanks to them, I could do kind of counseling with my friend.
Because he was worried if he got infected or not. He’s now under PCR testing. It takes time for him to get the result. But while waiting, people tend to be occupied with anxiety... But I could talk to him about things you’ve uploaded like risk factors. So now he’s felt better. That’s all because you’ve uploaded great and amazing videos on YouTube. Thank you, Dr Seheult. You’re the best!

[MedNerdDrWaqasFazal]

This is amazing... Such a resourceful video. Med cram is love ❤️

[IzzemMA]

Really, just a THANK YOU for your service to humanity in general, and this audience in particular. We learned more from you than any other resource

[tulsissurfboard]

Another gem from Medcram and Dr. Seheult. Can't wait to share this with friends and family.

[nauticalstar]

Dr. Seheult is always ahead of the curve.

[cotepm]

Welcome back after a well deserved vacations. Very interesting to follow the T & B cells immune response. Many thanks for giving us an understanding of the complex world of immunology. Salutations de Montréal.

[eriknystrom]

That seems to explain why areas that had many infections early on now seem to have a very low infection rate, (New York etc) . Areas with a crude mortality rate of 600 - 800 deaths/ 1 million inhabitants ( New York was even higher) now seem to have very low daily death. That indicates a herd immunity even with only 20% testing positive to the antibodies.

[rowenab.]

Good to see you back again Dr. Seheult!

[scottwoodworth]

The Nature article below suggests SARS (2003) T Cell reactivity is still present in patients today... 17 years later. Similar family of virus. It is clear that long term immunity is far more complex than just the IgG antibody testing which is the current focus of immunity duration.

[ChefSupaPmp]

Good to hear your voice again. I very much enjoy these updates and feel more enlightened with every one you share.

[alaindumas]

1: I read that medical deaths certificates are only established in 20% of India's deaths so their numbers are questionable. 
2: It is about time that we remember that antibodies are relatively easy to detect but only a small part of the immune response. In humans, we measure specific antibodies levels after Covid or vaccination because an experimental infectious challenge is unethical but decreasing levels after a few months may not mean lack of protection. Memory B and T-cells will survive and respond to future viral challenges. Non-specific immunity is also hard to evaluate but often effective.
3: While many explain the low or high incidence of Covid-19 in various countries by their public health interventions, I always thought that cross immunity to previous coronaviruses had to play a role in the very good numbers observed in China and neighboring countries irrespective of their very different strategies. I am looking forward to new studies exploring this topic as well as the correlation with Vit D levels.
Dr Dumas

[WuesteGobi]

Thank you so much for all the work you are putting into Medcram

[jeffbohn]

Woo it's good to have you Back Doctor!

[r.m.halcyon]

This is excellent analysis and cross-referencing to explain asymptomatic ratios and the need to wear respiratory barriers in unventilated public places for both exhalers and inhalers to reduce viral load (and work toward herd immunity via more harmless infections?)

Question: if 1/3 (Netherlands) to 1/2 (Singapore) of people appear to have T-cell based immune response already and authorities will accept vaccine efficacy as low as 50%, shouldn’t there be this T-cell screening before vaccinating up to half of the worlds billions unnecessarily with questionable half-effective serum?