The Presidementia says the epidemic is over so I can stop doing these research summaries soon. Of course, Biden isn’t actually in charge of anything so the lockdown nuts in the administration immediately walked back his comment. Lot of stuff from the CDC today, I have generally ignored them for a while, but there are a few interesting studies published by the agency.
This research from the CDC indicates that among persons hospitalized for CV-19 treatment, mortality was over 15% during the Delta wave, but dropped to around 5% during Omicron, even though the persons hospitalized during Omicron has worse overall health. One interesting sidelight is that the hospitalizations were filtered to ensure that they were primarily for CV-19 treatment, showing that it is pretty easy to do this. And the study found that 37% of supposed CV-19 hospitalizations, when accurately assessed, were not actually for CV-19 treatment. So the hospitalization rate across the epidemic has likely been overstated by more than a third. While Omicron probably induces less serious infection, the reason for the reduction in hospital mortality is probably a combination of infection and vax-derived immunity and better treatment. (CDC Study)
CT values for postive tests during Omicron were higher on average than in the earlier epidemic period, indicating lower viral loads, but more tests with high CT values supposedly resulted in culturable virus being found. How much culturable virus was not reported, so not sure what this study really means. (CDC Study)
Another piece of research, this one from the CDC, on the pattern of the four prior seasonal coronaviruses, which is amazingly consistent with what we saw from Omicron. Seasonal coronaviruses infections tend to start in October to November, peak in late January to early February and wind down in the April timeframe. That pattern exists most strongly in temperate latitudes, in more tropical ones, i.e. the American south, the pattern is more mixed. Interesting discussion again of factors thought to be related to seasonality. (CDC Study)
The tidbit in this study is that during Omicron, transmission in households was the same for vaxed and unvaxed persons. The study comes from Spain and found that the overall rate of transmission to household contacts increased to over 80% during Omicron. While vaccinated persons appeared to be less likely to get infected shortly after vaccination, the effect wore off. Later in Omicron, vaxed people actually had a higher rate of infection. (CDC Study)
This is an excellent two-page article shich gives an explanation of T cell functioning and the role of T cells in suppressing and following a CV-19 infection and following vaccination. (Science Article)
Persons who are vaxed following a CV-19 infection have a greater and longer-lasting antibody response than vaxed persons who have not been infected. And the effect grows with age, perhaps because older persons are more likely to have had a symptomatic or serious CV-19 infection. (Medrxiv Paper)
And another study suggests that antibody maturation occurs more quickly following infection than after vax, leading to a stronger neutralization capability. The antibodies created by infection were also more effective against new variants. (Medrxiv Paper)