In the past week we learnt that remdesivir is indeed effective at reducing COVID-19 mortality, whereas neither lopinavir-ritonavir nor hydroxychloroquine work. We also learnt that psychiatric patients in London are at an increased risk of testing positive for COVID-19, and that six owners in Hong Kong have infected their cats.

Transmission

19% of healthcare workers in Sweden tested positive for COVID-19 by serology, higher than in the general population, suggesting hospital transmission. The outbreak in Los Angeles was seeded by cases from Europe, and not by cases from China, according to a genomics analysis. Six cases of human-to-cat transmission were identified in Hong Kong.

A surge of travel from Wuhan for Lunar New Year led to transmission of the virus across China, according to a modelling study. Travel restrictions were imposed after the festival, one of the world’s largest annual migrations. An analysis of viral genomic sequences from China suggests that a small number of individuals were responsible for a large number of spreading events, which may indicate a role for super-spreaders in transmission.

More crowded cities were predicted to have longer epidemics with more total cases than less crowded cities, according to a model. Only three US states have maintained sufficient non-pharmaceutical interventions to contain the local epidemic of COVID-19, with many states relaxing measures too early, according to a new transmission dynamic model.

Virology

SARS-CoV-2 expresses proteins that disrupt splicing and host cell protein translation, in order to suppress the interferon response.

Immunology

B cell activation was associated with inflammation and severe symptoms in COVID-19 patients, with some indications of auto-immune disease.  Patients with high expression of interferon-stimulated genes had more severe disease than those with low expression, again pointing to an over exuberant immune response in pathogenesis.

Treatments

The largest trial of remdesivir has now been published, with more than 1000 participants, and showed that those who received the drug had a time to recovery of 10 days, compared to 15 days for the normal treatment group. Remdesivir patients were also more likely to show clinical improvement at day 15, and had a mortality rate of 7%, compared to 12% in the control group.

The RECOVERY trial published two negative results: for hydroxychloroquine and for lopinavir-ritonavir. The HIV drugs lopinavir–ritonavir had no effect on COVID-19 mortality or time to recovery, and hydroxychloroquine resulted in a small increase in mechanical ventilation and death, including a small increase in cardiac deaths, and no reduction in 28 day mortality.

A metallodrug, ranitidine bismuth citrate, used for Helicobacter pylori infection, was effective against SARS-CoV-2 in vitro and in Syrian hamsters in vivo, by acting on the viral helicase. A structural based analysis identified potential drug targets against the viral protease.

Biomarkers of severe disease

A mortality risk predictor was developed based on clinical data at admission.

At risk groups

38% of psychiatric patients in London hospitals had COVID-19, a far higher prevalence than in the general population.

Clinical findings

A comparison of COVID-19 and influenza patients in the US, South Korea, and Spain found that those with COVID-19 tended to be male, younger, and with fewer comorbidities than those with influenza.