We study innate and adaptive immunity to #viruses and #cancer. #COVID19 #immunology #vaccines @HHMINEWS @YaleIBIO @YaleMed @YaleEMD @YaleSPH.
What is the relevance of viral load in #COVID19 disease severity? A very talented @YaleMSTP student @SilvaJ_C found that saliva viral load to be a better predictor of disease than nasopharyngeal viral load. Here is a thread to explain the findings. (1/n)
I preface by saying that numerous fantastic studies by many have demonstrated nasopharyngeal viral load to correlate with disease severity and mortality, while others do not find such correlation. Here are some of these studies. (2/n) pic.twitter.com/XyunWFP0Bp
Being at @yale, the birthplace of #SalivaDirect and everything saliva bc of awesome colleagues like @awyllie13 @NathanGrubaugh @VogelsChantal et al, we had access to both saliva and nasopharyngeal (NP) samples from the same patients to do direct comparisons. (3/n)
We already knew that saliva is an easy and reliable way to detect viral load in patients, thanks to the great work of colleagues here @YaleSPH @YaleMed. @awyllie13 et al. (4/n)
What about saliva’s ability to predict #COVID19 disease? @SlivaJ_C compared first whether saliva and NP viral load correlates with risk factors, age, sex. Saliva (top panels) but not NP (btm panels) viral load correlated with all of these. (5/n) pic.twitter.com/EgK8z2JERS
Next, @silvaJ_C examined whether viral loads correlate with severity of #COVID19. Saliva (top panels) but not NP (btm panels) viral load was elevated in hospitalized, severe and deceased patients. (6/n) pic.twitter.com/NLEJqbG2aT
Moreover, saliva viral load (top) and NP viral load (btm) declined over time in patients that survived #COVID19 but not those who died (purple). Patients with lethal disease maintained v. high viral load over the course of disease. (7/n) pic.twitter.com/sCU6aa2vKG
What associates with saliva viral load? Most influential predictors of saliva viral load was assessed by running a non-linear iterative
partial least squares (NIPALS) analysis of all factors and then assessing for variable importance with Variable Importance Plot (VIP). (8/n) pic.twitter.com/n9Z6RHXZVD
Positive correlation with saliva load: the usual suspects-chemokine, cytokines, IFNs.
Negative correlation with saliva load: antiviral antibodies and platelets.
We know early antibody kinetics is key to survival @carolilucas @sneakyvirus1 et al. (9/n)
Time spent in the high, medium, and low saliva viral
load brackets was compared. Deceased
patients spent longest time in the high saliva viral load bracket, while non-hospitalized spent shortest time with high viral load. Moderate/severe in between. (11/n) pic.twitter.com/9aWK7jdTgX
Why is saliva viral load a better correlate of disease than NP load? We think that NP only reflects upper respiratory tract (URT) viral replication, while saliva represents both URT and lower respiratory tract. Mucociliary clearance propels virus from LRT to oral cavity. (12/n) pic.twitter.com/1kCqE4YgM0
URT virus is key to transmission, but LRT is key to severe #COVID19. Saliva appears to be better at capturing the critical viral source driving severe disease.
This was once again an amazing collaboration with the Yale IMPACT team 🙏🏼 Led by @SilvaJ_C 💪🏼 (end)
Omar Yaxmehen Bello-Chavolla
Sun Jan 10
Extraordinario hilo de @VirusesImmunity sobre la importancia de la carga viral de #SARSCoV2 para predecir #COVID19 grave:
✅ Pruebas basadas en saliva son superiores al hisopado nasofaríngeo
✅Una carga viral ⬆️ se asocia con ⬆️ severidad
Wow. This is amazing work but also immensely frustrating. The amount of gate keeping we faced from FDA for getting saliva testing was immense. The concordance with NP was sacrosanct and frankly stopped larger testing efforts using saliva from having an earlier foothold. 😡 twitter.com/virusesimmunit…
The questions about relationship of viral load and severity of covid, and its assessment by saliva compared with nasopharyngeal, addressed in this illuminating work and ★ thread twitter.com/VirusesImmunit…
Fascinating thread about viral load in saliva. In my world, I take these numbers (huge variability, as seen in other studies) and estimate that if an infected person counts from 1 to 100, they release about 1 (10^0) to 10 million (10^7) viral RNA copies in aerosols. twitter.com/VirusesImmunit…
👇Very important work from @VirusesImmunity. Saliva test is easy and cheaper for mass deployment and can be set up by individual communities for screening. @GeorgiaTech has done this since fall @genomestake @joshuasweitz. Now, saliva viral load seems better predictor of #COVID19 twitter.com/VirusesImmunit…
2/ I find the presence of novel coronavirus in saliva fascinating. Why the heck is it there? Prof. Iwasaki doesn't answer that question (which is fine!🙂). Their goals here were to show a fascinating correlation between saliva viral loads (GE as surrogate) and disease severity. pic.twitter.com/pX9GkScIIO
4/ One of my favorite pre-prints is the only paper to directly follow virus-specific T cell responses and viral loads in the same people, and they observed that people with early T cell responses had the best outcomes.
@profshanecrotty Interesting to note that it the opposite of humoral responses
'We observed that while rapid induction and quantity of humoral responses were associated with increased disease severity'
@profshanecrotty The trend of high abs and disease severity has been noted all over the place. Some classic Coffman & Mossman papers might be today's bedtime reading. (more detailed data on IgG subtypes would be nice)
Viral load in saliva samples correlated with #COVID19 disease severity. Important finding. If viral load in a sample can predict disease severity that would be an early warning sign for intervention. twitter.com/virusesimmunit…