How about starting with yet another seroprevalence or antibody study, this one from England. (Medrxiv Paper) The survey covered almost 100,000 somewhat randomly selected adults who completed a survey and a self-administered antibody test. Overall prevalence was around 6% or about 3.36 million adults by July 13. About a third of those who were positive were asymptomatic. Prevalence was highest in London, among those aged 18 to 24 and among minorities. For comparison, on July 13, according to Worldometers, the UK had reported 291,000 cases. So less than 10% of cases were actually detected by a positive test. The US and the UK are testing at very similar rates, so if you apply that ratio to the US, we are approaching 60 million cases. Please note again that concerns about the accuracy of antibody tests, and their inability to measure a more comprehensive immune response, mean the results of these studies should be used with caution.
Another prevalence study comes from Italy. (Lancet Article) Out of over 4000 people tested, 22% were positive, with prevalence rising significantly with age.
The extreme efforts to suppress coronavirus infections are likely having an effect on influenza. Some data in the US suggested a dramatic drop as the epidemic began to take hold, but influenza is seasonal anyway and influenza testing dropped as CV testing rose. This article discusses influenza in the CV era. (JAMA Article) The focus is on how a case should be handled clinically, particularly in late fall when influenza typically begins to increase. Testing for both viruses is discussed as well as treatment implications.
Minorities are undoubtedly disproportionately being infected and experiencing serious coronavirus illness. The primary factor in this, however, is an underlying greater burden of pre-existing illness. Another paper shows this to be the case. (Medrxiv Paper) This was a review of a large number of studies on the topic and concluded that after accounting for comorbidities, there was little difference in risk across racial groups.
I do not understand how some researchers seem to find evidence that antibodies against this coronavirus persist for as long as they can be measured, which isn’t too long for this epidemic, and others keep saying they disappear. I suspect use of different assays with different capabilities is largely to blame. This paper finds that antibodies appear to have good persistence. (Medrxiv Paper) The paper focused on development of adaptive immune response in persons with mild disease. It gives an excellent summary of the workings of the adaptive immune system in the first page or so. 15 patients recovered from mild illness were tested out to an average of three months. Healthy controls were also tested. They were careful to distinguish between antibodies and immune responses developed in fighting the acute infection from those that are created to protect against reinfection. The researchers found that all the persons with mild disease developed a strong, neutralizing response that actually increased in most cases by the end of the followup period. Interestingly some potential cross-reactive response was found in the healthy controls. Again, a very positive study for the likely protection against re-infection even in persons with mild disease.
Look, there can be no disputing that a face covering or mask will block certain particles from coming in or out of the mouth and nose. Here is another study that finds that. (Medrxiv Paper) The researchers used a manakin and human subjects to determine the efficacy in blocking droplets with a surgical mask or cotton mask. They found a 1000 fold drop in the number when using a mask. They also noted that if there is aerosol transmission, and there almost certainly is, the efficacy of masks is overstated. But the real point is, what difference does it make what the effect of a mask is on droplets if they don’t actually appear to reduce transmission and lower cases. There is no evidence in the real world, either from countries or US states, that more mask wearing is associated with fewer cases. Why is that? Probably because of a combination of improper wear, not wearing them in the biggest locations for transmission, i.e., the household, touching the mask, seepage, and most importantly, just odds. No mask is perfect and sooner or later, if you are around the virus enough, you are going to be infected.
Here is an interesting paper about coronavirus on a fishing vessel with a crew of about 120 people. (Medrxiv Paper) Everyone was tested before the ship left port and three had been positive by antibody testing. While at sea there was an outbreak, affecting about 80% of the crew. None of the people with antibodies from prior infection developed any symptoms of re-infection, suggesting that the antibodies they had previously developed were in fact protective.