A Head Full of Coronavirus Research, Part 59

By November 17, 2020Commentary

By Tuesday, the pre-prints are picking up, so a few interesting studies today.

This paper assessed whether the timing of mitigation of spread actions has an impact on cases.  (Medrxiv Paper)   The study analyzed 87 interventions across 17 countries for their impact on mortality rates.  They authors also conducted a literature review.  They found no association between the initiation of an intervention and mortality rates.  In particular, being faster in implementing a measure after the Chinese came clean, or the country first experienced a case or a death, had no association with the country’s mortality rate.  These results rebut the notion that earlier implementation of mitigation measures would lower cases or deaths.  Of course that is likely because these measures are futile.

We are continuing to see more papers finding that there is a long-lasting extensive adaptive response to CV-19 infection.  Here are two new papers in this area.   In the first, T cell response was probed  for up to 9 months post infection in 32 Chinese patients.  (Medrxiv Paper)   A few patients showed signs of some decline in response and they tended to have had asymptomatic infections.  People who showed some antibody decline were less likely to have a T cell response that stayed stable.  In the second paper, 185 patients were followed for up to 6 months.  Antibodies were relatively stable, memory B cells actually increased.  T cells showed a more variable course, declining in some patients.  Overall, my takeaway from this body of research is that we can assume that infected people have an adequate and lasting immune response to fend off re-infection.

Another paper that examines the relationship between viral load and severity of disease.  (Medrxiv Paper)   448 Spanish patients were used in the study.  Nasal swabs were used to collect samples for PCR tests.  Lower cycle numbers were clearly associated with more severe disease.  So it is important that this metric be reported with the test results.

An updated version of the Gomes paper using a model that includes more heterogeneity in infectiousness and susceptibility in a population.  (Medrxiv Paper)   The paper continues to find that transmission may slow substantially at relatively low levels of infection in the population.

This is another in the line of studies suggesting that some vaccinations may offer protection agains CV-19.  (DTP Study)  The authors checked a number of vaccines and pathogens to see if they contained sequence fragments similar to CV-19.  Most did not and therefore were unlikely to offer cross-reactive protection.  The Diphtheria, Tetanus and Pertussis vaccine, however, did show significant cross-reactive potential and stimulation of T and B cell responses.  Almost all children receive this vaccine, which may be a factor in their lower risk.

And for those who like to have lots to worry about, this study checked the persistence of CV-19 on fresh produce.  (Medrxiv Paper)   A seasonal coronavirus was used, not CV-19.  In general the virus was gone with 24 hours after being placed on the produce item.  But cucumber retained it for up to 3 days.

Join the discussion 3 Comments

  • Peter S. says:

    Cucumbers are usually packaged with a thick coating of edible wax. Cukes are prone to drying out, and the wax helps them retain moisture. That would be my guess for why they hold viruses longer.

  • researching says:

    Promising recent study on drug called “baricitinib”; might be worth looking at for one of your “research” posts.
    https://advances.sciencemag.org/content/advances/early/2020/11/13/sciadv.abe4724.full.pdf

    Twitter thread on baricitinib here:
    https://twitter.com/boriquagato/status/1328072668772446208

  • John Liljegren says:

    I’ve looked at the third linked study, about the relationship between viral load and severity of disease for 448 Spanish patients.

    Figure 1, shown on the last page, shows CT values for patients deemed severe, moderate, or mild. Figure 1 is not gridded, so the precise CT for each “x” is hard to discern. But at 40 CT’s and above, I count: severe– about 5 out of 102; moderate–19 out of 236; and mild–13 out of 110.

    It looks to me like the hard-to-see 75% bars are at higher than 35 CT’s for all three groups of patients.

    By my estimate, at 35 CT’s and higher, there are roughly: severe–35-40%; moderate–at least 40%; mild–at least 55%.

    My point? Everything I’ve read indicates that CT’s 35 and higher, and maybe even lower, are unlikely to be from viable virus. The authors of this study do not address that at all. And the Table on page 10 has no indication of CT numbers at all. There certainly is no correlation shown between CT’s and the Table’s 17 listed characteristics and three levels of disease severity.

    If even I know about the problems in using PCR test results to “prove” the existence of a viable virus, how in the world at this date do the “experts” not even discuss the issue?

    They failed to deal with that issue. And they failed to do some virus cultures on some significant percentage of the patients [I’d think 20% would be a good figure] to get a better estimate of what the various CT counts actually show in the way of genuine infection. That is, at let’s say a CT count of 30, what percentage generate a viable virus in a culture? Without doing that, I don’t see how they can truly know the viral load.

    Without that data, I conclude that some big chunk of the patients were not sick with COVID at all. And yet they had symptoms, including moderate and severe. Which means it is possible that big chunks of the people with lower CT numbers may also not have been infected with CV-19. Maybe something else caused their symptoms.

    Thus, I don’t see how studies like this provide any useful information at all. Am I being to hard on the poor little scientists?

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