Another commentary on the foolishness of keeping children out of schools, this one from the British Medical Journal. (BMJ Article) The authors again summarize the evidence of lower infection rates, much lesser role in transmissibility and less severity of disease. Their conclusion was clear “Governments worldwide should allow all children back to school.”
That study that I reported on about mask use saving all these lives has been ripped by scientists, many of whom support mask use but who say this study was worthless from an experimental design perspective. (NYT Article) I am sure masks may do some good in limiting transmission, but I think they are being way oversold.
This study addresses the likelihood of being symptomatic after infection with coronavirus. (Arxiv Paper) The authors examined 4327 contacts of persons with known infection and performed infection and antibody tests on this group. 54% were found to have been infected, and two thirds of those were identified by the antibody test. There was a dramatic age difference in likelihood of developing symptoms, with only 18.6% of those under age 20 ever having a symptom, to 67% of those over 80 having them. 69% of people who were positive and who were under the age of 60 never developed any symptoms. 6.9% of those over age 60 ended up with critical disease. Males were at higher risk of critical illness. This is an important and well-done study that once-again shows a high rate of asymptomatic cases and a strong age skew in serious illness.
Hoping to see a fuller analysis at some point, but the latest results from North Carolina’s ongoing antibody prevalence study finds that of 5000 people tested, 10% have positive results but only 4% of those had previously tested positive on an infection test. (NC Study) Over the weeks that the study has been ongoing the proportion of positive results has risen steadily. Once again we see the suggestion that a very high percent, perhaps over 90%, of infected individuals are not being detected.
Here is another homeless shelter study, this one from San Francisco. (Medrxiv Paper) About 3953 residents and workers were tested, with a total positivity rate of 2.1%, with 52% being asymptomatic.
Do immune system variations in the proteins that present foreign substances to the immune system have anything to do with coronavirus illness susceptibility? That question was explored in this paper. (Medrxiv Paper) The researchers looked at genetic variation in regard to major histocompatibility complexes, which evaluate substances for their “foreignness” and human leukocyte antigen proteins, used by MHCs to present those substances. There is substantial variation in these genes and that variation can occur by country or ethnic background. The researchers believe that they identified a number of potential cross-reactive complexes, established both by prior coronavirus strain infections and other viruses. They also believe they found a link between certain variations and death rates. Another interesting piece of the pre-existing immune defense puzzle.
This paper looked at antibody development both in the blood and saliva. (Medrxiv Paper) Because of concerns that people with mild infections may not develop as strong an antibody response, the authors used a more sensitive assay and looked both in the blood and saliva secretions, as antibodies can be developed separately in the two body systems. They examined both symptomatic and asymptomatic patients. 18 hospitalized patients with confirmed infection, 39 non-hospitalized patients with confirmed infection and 6 asymptomatic persons with confirmed infections were the subjects. Spike protein and nucleocapsid protein antibodies were tested for. The authors identified a combination of methods that was more sensitive to detecting various antibody types. They found significant antibody development in blood and saliva for all patients with confirmed infections, but much stronger ones in patients with more severe disease. But there were some patients with asymptomatic or mild disease for whom antibodies were only detected in saliva.
Understanding common routes of transmission has obvious importance. This research looked at household transmission in a city in China. (Lancet Paper) The authors used contact tracing from an infected individual to identify transmission within their household and to persons outside the household. The rate of infection from a primary case to a secondary person was 12.4% based on relatives and 17.1% based solely on address. Young people had the lowest rate of secondary infection and those over 60 the highest. The transmissibility rate within a household, with obvious close, consistent contact was well under 1.