A few more interesting pieces of research. The first deals with relative viral loads in nasal versus saliva specimens. (Medrxiv Paper) The study covered 67 patients who self-collected both types of specimen. The nasal swabs indicated higher viral loads than did the saliva specimens. On both types of samples, loads were higher closer to the date of symptom development. All samples were cultured and no culture was positive for a sample taken more than 11 days after symptom development. Saliva sampling was more likely to detect patients who were still infectious. The authors point out numerous opportunities for variability in saliva sampling, but also recognize that it may do better at finding actual infectious patients.
How many people in Orange County, California have had a CV-19 infection? This paper attempts to answer the question with an antibody survey. (Medrxiv Paper) It is a big number, among about 3000 tested people, 11.5% were positive on an adjusted basis. The authors made substantial efforts to have this be a representative sample. Rates were higher among Hispanics and low-income people. This prevalence is seven times that indicated by infection testing results in the county.
Another study on what factors may be associated with increases in cases, this one from Germany. (Medrxiv Paper) The authors were looking at whether school holidays, an extended period when school was off, were linked to growth in infections. Using many school districts, they examined the period two weeks before, during, and two weeks after the holidays. Obviously during these holidays, families may be traveling and engaged in other activities that increase contacts. The researchers believe that about 30% to 50% of case growth was associated with school holidays, with the effect stronger in the former West Germany than the East. It also was more notable among wealthier families. So I guess the lesson is, keep the kids in school.
This study is a contact tracing one that followed students who were infected in a camp setting to see if and to what extent they infected others upon return home. (Medrxiv Paper) I believe this is a follow-on to the CDC study on the Georgia camp outbreak. There were 224 primary cases in 194 households, with a median age of 14. 82% of these children were symptomatic but none were hospitalized. There were 526 household contacts, with a median age of 46. 434 of these were interviewed, 14% had at least one underlying medical condition. Only 35 households had a secondary case, 48 in all, most of which were symptomatic and 4 of whom were hospitalized. The secondary attack rate was 9%, if the returning children were in fact responsible for the transmission. The study does show likely transmission from younger persons in a household to others in the household.
Another study indicating that being infected with CV-19 tends to boost antibodies to the seasonal coronaviruses. (Medrxiv Paper) This may not be a good thing, as the body’s reliance on boosting those antibodies may deter it from developing stronger sets of CV-19 specific antibodies, according to the authors. They identified only a minor cross-reactivity from seasonal coronavirus antibodies against CV-19.
Finally, this study from Sweden confirms what we observe regarding fatalities, it is the frail elderly who are most at risk. (SSRN Paper) The researchers examined factors associated with death among 225 hospitalized patients, 27% of whom eventually died. Higher age, chronic kidney disease and prior stroke were the factors strongly correlated with death. Among patients over 65, having a higher score on a clinical frailty scale was the strongest predictor of death. In other words, as we see in Minnesota and everywhere, those who already near the end of life are the most likely fatalities from CV-19.