Full Version: Cluster Investigations — real data from Hawaii
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On the Cardboard, several members expressed an interest in learning the result of contact tracing studies. I stumbled across data from cluster investigation reports in Hawaii, released in the Honolulu Star Advertiser.
The data is selectively released, so one could argue that it may not be representative, but I haven’t seen anyone else releasing this information.
A few takeaways I have gleaned:
1) The vaccine, unsurprisingly, is extremely effective. Time and again outbreaks occur among unvaccinated attendees at events, and large outbreaks occur where there are large concentrations of unvaccinated people.
2) Unfortunately, it seems every week there are multiple outbreaks at restaurants, and I was surprised and disappointed to read how many restaurant employees choose not to be vaccinated.

The most recent article in the Star Advertiser:
Archives of all released cluster investigation reports:

If you open up the pdfs on the previous link, sometimes they give a lot of detail into their investigations.

This is the best cluster investigation information I've encountered so far.
Thanks! Interesting reading....
To adjust for the level of community infection:
Hawaii:  19.6 cases/100K in last 7 days.  (1.4M people)
California: 19.5 cases/100K in last 7 days  (~40M people;  ~1.95M in Santa Clara County)
Nevada: 105 cases/100K in list 7 days (highest)
Vermont: 5.5 cases/100K in last 7 days (lowest)
US: 26.6 cases/100K in last 7 days

Some clusters of interest:
  8 of 15 party-goers at an outdoor party (post-graduation) got COVID.  I think too many people feel if it is outdoor, they are safe.  (Presumably there was food & drink, requiring masks to be off some of the time).

Quote:In late April 2021, the Hawai`i State Department of Health investigated a cluster of 38 COVID-19 cases associated with a fast food restaurant on Oahu. Eleven of 35 employees were diagnosed with COVID-19 (attack rate: 31%). None of the 11 employees had been vaccinated. In addition, we identified 27 secondary cases among household members, including four of whom were employees at three other fast food restaurants. Among those three other fast food restaurants, we identified two more clusters with a total of seven cases in employees.
Despite conducting pre-shift COVID-19 symptom checks, employees were allowed to work with symptoms.

I hadn't previously thought about the situation of family members taking cases to other associated places (other than the problem of siblings in different classes or schools).
(This set of reports also suggests that carpooling was a factor in some other workplace clusters.  Ever notice how the various governments say almost nothing about clusters from public transportation?)

Faith-based gatherings are other sources of clusters in their reports.
Singing (choir; instructional) & performance arts (dancing) were also sources of clusters.  The issue of practicing singing & instructional singing (private teacher infected pupils one at a time) is something that may happen in the fall in schools, or at music gatherings.  There was a suggestion of  spreading during dressing & make-up preparation for performances.
In one case, they had barriers taken down that were intended to keep people separate, as they served to reduce air flow.

Some negatives of these reports in my opinion:
1)  They are inconsistent in identifying vaccinated vs unvaccinated cases.  They highlight it when all the cases are unvaccinated, giving what I think is over-emphasis to that feature.
2)  Clusters are counted when people gather (BUT, did you notice that they don't seem to consider clusters when they are a household -- for instance, the fast food situation could have been blamed on a household cluster that then spread to several places of employment).  I believe this is a somewhat distorted way of looking at things.  For instance, one infected person might infect 30 people as he walks down the street, but they would never notice that and not count it as a cluster.

I do expect that the amount of time when the nose and/or mouth are uncovered (eating, drinking, singing) are significant to the spread.