This is another in the emerging line of studies building epidemic models with some capability to account for variation in susceptibility to infection. (Arxiv Paper) The authors explain how something called dynamic causal modeling could be used to adjust models based on findings from immune response studies and surveys and the resulting variation in susceptiblility. A pretty theoretical paper but interesting information on the level of variability in immune response and the impact on epidemic course.
This study looked for antibody prevalence among schoolchildren in Switzerland. (Medrxiv Paper) They found a prevalence of about 3%, which was similar to the community rate. No clusters were found. The rate was much higher than that shown by PCR testing, in fact 90 times higher.
Researchers keep looking for associations between risk of infection and various factors. This brief article summarizes findings on blood type, saying there may be a link between cases and blood type, but not severity of disease. (JAMA Article)
Blood donations may be a way to test for antibody prevalence and a couple of studies have done that. Here is another one, from the Red Cross across most of the country. (JAMA Article) Over 950,000 donations were tested, less than 2% were positive. Rates increased throughout the study period. Blood donors may be less likely to have been sick with CV-19. A similar result was reported by another blood collection firm in another paper. (Medrxiv Paper)
Do antibody tests perform uniformly across sub-populations? This study looked at the question. (Medrxiv Paper) And in fact differences were found by sex, age and minority status. The study was comparing antibody results to positive PCR test results, so false PCR positives would have made the antibody test appear less accurate. But the variability across populations and tests would remain.
And here is a letter from doctors in Belgium who think that the reaction to the epidemic has been unbalanced and damaging. Thanks to a reader for sending the link and it is worth a read. (Belgium Letter) I tend to agree with every argument they make, particularly about the lack of balance in considering lives other than those of CV-19 patients.
This study talked about the potential effects of co-infection of CV-19 and influenza. (Medrxiv Paper) The study comes from England. The researchers found about 58 cases of co-infection in over 19,000 patients. Older patients tended to be more likely to be co-infected. There was some evidence of viral competition as influenza patients tended to be less likely to have a CV-19 infection than were patients overall. But when co-infection did occur it was associated with more severe disease.