My Virtual Reading Room

From Medscape:

COVID Testing FAQ, From Reinfection to Persistent Positives

Does a positive COVID-19 PCR test result indicate that the individual is infectious?

Because the COVID-19 PCR tests only detect a fragment of the viral RNA, a positive test does not mean that infectious virus is present. In one small study of people who had mild or asymptomatic novel coronavirus infection, virus was not cultured from the upper airway after day 10 of illness, but detection of viral carriage by the molecular assay has been seen more than 80 days after the initial infection.

COVID-19 Vaccine: Latest Updates

(June 10, 2020 — With more than 160 potential vaccines for COVID-19 under study, optimistic experts hope that a viable vaccine may be ready by the end of 2020.

Other experts caution that the timeline may be unrealistic. Only a small number of those vaccine candidates are being tested on people, and chances are many of the other projects won't survive beyond the laboratory stage.

Even so, vaccine experts point out that funding has been plentiful, many different approaches are under study, and collaborations between small firms developing the vaccines and large drug companies with the capacity to mass produce them all give reason for hope.

Dexamethasone Hailed as 'Breakthrough' in COVID-19 Trial, Reduced Deaths

(very interesting how clinical research has gone back and forth about the use of steroids...)

Viral Shedding and COVID-19 Superspreading Events

Infectiousness, Testing, and the Myth of Reinfection

Polymerase chain reaction (PCR) assays that look for viral genetic material show that some individuals are positive for SARS-CoV2, for weeks or even months. A recent modeling study published in Emerging Infectious Diseases estimated that 50% of infected people are PCR positive until day 22, and some are positive out to 2 months after symptom onset.

However, PCR assays just detect presence of viral RNA and do not measure whether that viral material can cause infection. Until recently it was not clear whether those who are PCR positive for weeks are still infectious.

Now multiple studies have shown that infectiousness declines rapidly after symptom onset and, in general, i))nfectious virus has not been isolated 8 days after symptom onset.

Cutting the Tail: Containment of Spread

Early evidence points to superspreading events of SARS-CoV2 occurring predominantly in closed environments with poor ventilation where people are closely packed and are exposed for long durations, particularly with face-to-face contact (>10 minutes).

The implications for "cutting the tail" of infection spread are many. Viral load is thought to play a major role in superspreading events, and viral load peaks just before symptom onset, making universal masking critically important to slow the spread of the virus.

Why Are Minority Populations More at Risk for Contracting and Dying From COVID-19?

In some cities, 60% of COVID-19 cases and deaths are in people of color.

Three critical areas are driving the COVID-19 disparities among racial and ethnic minorities: clinical risk factors such as cardiovascular disease, hypertension, and diabetes; access to healthcare; and social risk factors such as homelessness, incarceration, and food insecurity.

A large portion of the 27 million black and Hispanic Americans are uninsured and have reduced access to healthcare.

Regardless of socioeconomic status, black Americans die at higher rates than white Americans do. Discrimination and bias in healthcare play a role in these disparities.