Coronamonomania Lives Forever, Part 41

Vaccines continue to be the focus of the research but other items roll in as well.  Puerto Rico has a very high vaccination rate and a low level of cases at this time.  This research examined vaccine effectiveness over time.  As just about every study is showing, vaccine effectiveness against infection peaked early and declined by 4 to 5 months after vaccination.  The peak according to this study was in the 85% range for the mRNA vaccines.  Protection against serious disease remained stronger over time.  But for the elderly, especially those over 85, protection against both infection and serious disease was much lower.  Note this carefully:  there was no difference in effectiveness against Delta.   Another indicator that this variant is over-hyped.  (Medrxiv Paper)

And another paper showing that people who have already been infected at the time of vaccination have a far stronger response to vaccination than do the those with no prior infection.  So it really is important in studies of vaccine effectiveness to identify subjects with prior infection in all comparator groups.  (Medrxiv Paper)

I also must say that this may sound impressive at first blush, but it really isn’t.  12-18 year olds have very, very low risk of being hospitalized for CV-19.  This study from the CDC in that age group claims that vaccines have a 93% effectiveness at preventing hospitalization.  But the follow-up period is only a couple of months, before the waning we know will occur.  And I am surprised it isn’t 100% in that time period in such an already low risk group.  Please note as well that most of these hospitalized teenagers had pre-existing health issues.  A lot of excluded patients from the analysis for partial vaccination and other reasons.  And very low numbers of actual hospitalizations.  (CDC Study)

We have too much testing of all types for CV-19 but many of the powers that be want even more testing.  Not a good strategy for getting out of the epidemic.  This paper discusses the use of rapid antigen tests, which are quite popular for school and similar testing and which tend to have more serious accuracy issues than do PCR tests.  The PCR test issue relates more to cycle number thresholds used.  Here are the fascinating nuggets from the study.  One is that a cycle number of 18 was most highly correlated with infectiousness.  For comparison, we have labs using thresholds above 35 (remember, the higher the number the less virus).  They also found that regardless of apparent accuracy issues in wrongly calling a person negative, a negative reading on a rapid antigen test was very highly correlated with not finding a level that reached infectiousness.  Generally, antigen tests were less likely to be positive in individuals who were not symptomatic or were past the symptomatic stage of their infection.  But as noted before, that isn’t a bad thing because the tests are not missing people who are not infectious.  In simple terms, the rapid antigen tests are almost always right if they have a negative result and you are negative, they are frequently wrong if they say you are negative when you are positive, but when they are wrong, you are not likely to be infectious.  (Medrxiv Paper)

Yet another paper showing antibody levels from vaccination decline after a few months.  More interesting is that while apparently 59 of 227 health care workers in the study had an infection after vaccination, only two were symptomatic.  (Medrxiv Paper)

This study looked at samples collected during different waves in a large Western Pennsylvania health system and gives more evidence that Delta is no more contagious than Alpha.  Average viral loads in samples tested was similar in the Alpha and Delta dominated waves, although both had higher average loads than the prior waves.  The average load was lower in older persons, which is likely consistent with a lower load needed to create symptomatic infection, with the symptoms more likely to lead to testing.  (Medrxiv Paper)

A vaccine safety study, using self-reported data so not so good methodologically but I know one of the researchers who is absolutely top-notch.  It is possible that people elect to participate because they had a symptom of some type that they attribute to vaccination.   The study finds that there are not a lot of serious adverse events associated with the vaccines.  Only 3% sought any medical of any type for post-vaccine symptoms and .3% reported being hospitalized.  (Medrxiv Paper)