SARS-CoV-2 infectivity correlates with high viral loads and detection of viral antigen and is terminated by seroconversion

Background

From a public health perspective, effective containment strategies for SARS-CoV-2 should be balanced with individual liberties.

Methods

We collected 79 respiratory samples from 59 patients monitored in an outpatient center or in the intensive care unit of the University Hospital Regensburg. We analyzed viral load by quantitative real-time PCR, viral antigen by point-of-care assay, time since onset of symptoms and presence of SARS-CoV-2 IgG antibodies in the context of virus isolation from respiratory specimen.

Results

The odds ratio for virus isolation increased 1.9-fold for each log₁₀ level of SARS-CoV-2 RNA and 7.4-fold with detection of viral antigen, while it decreased 6.3-fold beyond 10 days of symptoms and 20.0-fold with presence of SARS-CoV-2 antibodies. The latter was confirmed for B.1.1.7 strains. The positive predictive value for virus isolation was 60.0% for viral loads above 10 ⁷ RNA copies/mL and 50.0% for the presence of viral antigen. Symptom onset before 10 days and seroconversion predicted lack of infectivity with 93.8% and 96.0%.

Conclusions

Our data support quarantining patients with high viral load and detection of viral antigen, and lifting restrictive measures with increasing time to symptom onset and seroconversion. Delay of antibody formation may prolong infectivity.

Iowa FICSIT trial: the feasibility of elderly wearing a hip joint protective garment to reduce hip fractures

Hip fractures exact a heavy toll in the elderly population. While intervention strategies are being investigated to reduce the numbers of geriatric falls and to improve the body's resiliency, the geriatric population remains at risk for the mortality and morbidity associated with fractures. The Iowa FICSIT site is investigating the feasibility of passive protection of the proximal femur through the use of hip pads. The pad is designed to disperse throughout the pad the energy created in a fall. The focus of the Iowa trial is to determine if elderly will wear hip pads for the majority of their waking hours. Thirty subjects are being recruited from each of six elderly populations who are at high risk to fall and at increased risk of injury. To facilitate compliance, the following strategies are utilized: run-in period, graduated implementation, tailoring of wearing times, and self-report of compliance. Outcome measures include compliance rates and injuries sustained during falls.