The Count

Region	Cases	Deaths
World	16,535,241	654,061
US	4,396,913	150,027

Two papers find apparently contradictory results concerning the persistence of antibodies. The reasons for this difference are not immediately clear.

SARS-CoV2 antibodies persist for at least 3 months A massive screening study (51,829 individuals) by researchers at Mt Sinai Hospital found that >99% of PCR positive individuals develop antibodies to the virus. In contrast to recent studies suggesting that titers wane after 8 weeks, this study found that, in 121 subjects who were retested an average of 82 days after symptom onset, there was no significant decline after almost 3 months.

Canadian finds rapid drop in antibody levels over three months following infection A study of blood donors in Montreal who were found to have antibodies in the course of a seroprevalence study were followed for up to 4 months after initial symptoms and all showed a steady decline in antibody levels by 40-60% during this period. The implications of this in terms of immunity are not clear

Three papers on aerosol transmission support the potential for spread by airborne aerosols, but the likely dose from aerosols produced by mildly symptomatic or asymptomatic cases is usually low, They are primarily a concern in the context of prolonged exposure in confined spaces, particularly in the presence of COVID-19 cases with significant or severe symptoms.

First demonstration of potentially infectious aerosols A multi-institutional team has provided the first direct evidence that SARS-CoV-2 RNA collected from the air in the vicinity of COVID-19 patients is viable in cell culture. Previous studies have found airborne viral RNA in this setting, but this is the first to demonstrate viability. This adds to the evidence suggesting the potential for SARS-CoV2 to spread through aerosols.

Modeling of aerosols suggest risks from aerosol transmission of SARS-CoV-2 from those with mild or no symptoms are low Dutch researchers, coupling laboratory measurements with aerodynamic models, conclude that the likely dose of SARS-CoV2 from aerosols generated by asymptomatic or mildly symptomatic COVID-19 cases pose a low risk of disease.

Data from Diamond Princess consistent with aerosol transmission of SARS-CoV-2 Harvard researchers using a detailed model of all potential transmission pathways among passengers quarantined for 14 days on the cruise ship estimated that 40% of spread was due to long range aerosols. During quarantine, essentially all spread was the result of airborne spread.

Adults and Children with COVID-19 carry similar loads of SARS-CoV-2 Swiss researchers found no correlation between age in the concentration of viral RNA ins nasopharyngeal samples from 405 subjects across a broad age range. This suggests that the only difference in the capacity for children to spread disease as compared to adults is their force of expiration, which could limit spread since it is lower than adults.

Three studies document the range of neurological effects associated with COVID-19.

A French national study demonstrates a broad range of COVID-19 neurological manifestations A review of 222 cases with neurological manifestations found a many neurological conditions arising through different pathological mechanisms. The conditions included acute cerebral ischemia, encephalitis, Guillain Barre syndrome, and, most commonly, a newly described condition, COVID-19 associated encephalopathy, which involves delirium lasting ≥ 24 hours, sometimes associated with seizures, without other identifiable cause.

COVID-19 confirmed to affect olfactory region of the brain French researchers performed MRI studies on ten patients with anosmia (loss of smell) and found brain lesions in 30% of patients.

COVID-19 can cause acute demyelinating encephalomyelitis Researchers in Minnesota identified three cases of an extremely severe disorder known as Acute Demyelinating Encephalitis.

Viral load associated with COVID-19 severity and mortality risk Harvard researchers showed that viral load, particularly in plasma and sputum, were closely associated with disease severity and risk of death.

Model based on clinical parameters at admission predicts COVID-19 severity with >90% accuracy This model from Hong Kong may prove useful for triage based on conditions on admission and on Day 5.

COVID19 risks in Sub-Saharan Africa may be underestimated A study from Madagascar concludes that the lower than expected numbers of reported cases of COVID-19 in the region can be explained by a combination of the relatively late introduction of the disease, low detection rates, and the implementation of non- pharmaceutical interventions that reduced contact rates. The investigators predict this will be the largest health problem the region faces in the near future.

A country's cultural values predict its COVID-19 death rate Aggregated cultural values of nations, derived from World Values Survey data, are as important or more important than government mandates in predicting the impact of COVID-19. Whereas trust in institutions predicts lower COVID-19 deaths per capita, secular-rationalism and cosmopolitanism each predict more deaths. This suggests that open democracies may face greater challenges in limiting a pandemic.

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*peer reviewed.

Recent Posts Covid19- Ahead of the Curve.

Getting to Herd Immunity: Beware of Shortcuts The idea that we can get to herd immunity by allowing the young and less vulnerable to become infected leads to a dangerously flawed strategy. The results could be millions dead, hundreds of thousands chronically ill and a vulnerable population (the elderly and those with underlying health conditions) at risk of explosive outbreaks or forced into perpetual isolation.