The following is a brief roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.Modern nursing homes may be safer during pandemic

Older nursing homes and those with lower staff-to-patient ratios may experience larger outbreaks of COVID-19 than modern, better-staffed facilities, a study from Canada suggests. The data from the end of March through late May was based on 623 nursing homes in Ontario with a total of more than 75,000 residents. About 30% of the facilities experienced COVID-19 outbreaks, with roughly equal rates in for-profit facilities, nonprofit homes and government-run homes.

The likelihood that at least one resident would become infected with the coronavirus was related to the infection rate in the local community and to the total number of beds in the home, researchers found. But the size of the outbreak, and the number of patients who died as a result, were larger in for-profit homes, which tended to have lower staffing ratios and outdated design standards.

Newer standards "provide for larger and more private room accommodations, as well as less crowded and self-contained common spaces, whereas older design standards can have ward-style accommodation and centralized common spaces in which all residents can interact," the researchers wrote in a paper published on Wednesday in CMAJ. "Beyond promoting quality of life, newer design standards promote infection prevention and control, given that they limit infection both within resident bedrooms and among areas of a facility," they said. 

Virus level in nose and throat can help guide treatment

The number of virus particles in a nasopharyngeal swab sample may help doctors decide how best to manage the patient, a Swiss study suggests. The researchers analyzed viral loads on nearly 20,000 nasopharyngeal swabs obtained from more than 4,000 patients, using RT-PCR, the most accurate technique. Viral loads in the patients' nose and throat varied widely, with higher viral loads in the first phase of the disease. Later, in the second phase, viral load tended to be lower and inflammation was a bigger problem.

"This may be useful to help treatment decisions," the researchers wrote in a paper published on medRxiv ahead of peer review. Patients in a later phase, with declining viral loads and inflammation, would likely benefit from steroids or other drugs that inhibit inflammatory proteins, researchers said. The usefulness of the information will depend on the quality of the sampling, they point out. At their hospital in Lausanne, data on swab viral load is "now used not only for patient care, but also to define contagiousness," with particularly low values helping to identify patients who might be considered at lower risk of transmission.

Chloroquine and hydroxychloroquine fail again in new studies

Two studies published on Wednesday in the journal Nature add to evidence that the malaria drugs chloroquine and hydroxychloroquine are not helpful against COVID-19. One study found no notable antiviral effect of hydroxychloroquine against COVID-19 in primates. The other found no effect of chloroquine in infected human lung cells in test tubes.

Hydroxychloroquine has been touted by U.S. President Donald Trump as a COVID-19 treatment and the two related drugs have been investigated for their potential to treat the illness caused by the novel coronavirus in more than 80 registered clinical trials. But more and more data from clinical trials suggest the drugs are ineffective for either treating or preventing the disease.

In the Nature study of monkeys with coronavirus infections, hydroxychloroquine "showed no substantial antiviral activity, regardless of the timing of treatment initiation, either before infection, soon after infection or late after infection," the researchers said in a news release. 


COVID-19 infection rate likely much higher than reported

Coronavirus infection rates are far higher than public health data suggest, three research teams reported on Tuesday. For one study, published in JAMA Internal Medicine, researchers re-examined more than 16,000 blood samples from routine screenings such as for cholesterol collected from late March through mid May from individuals in 10 widely-spaced U.S. cities. Based on tests of the samples for evidence that patients had been exposed to the coronavirus, the researchers estimated that the total number of infections in those cities "was between 6- and 24-fold higher than the number of confirmed COVID-19 cases reported in each location."

The other two studies, published by the U.S. Centers for Disease Control and Prevention in its Morbidity and Mortality Weekly Report, found similar patterns in Georgia and Indiana. Still, all three studies suggest that most people in all of the studied cities have likely not yet been infected by the virus. Given that many people remain susceptible, adherence to evidence-based public health mitigation measures like social distancing, face covering, and hand washing "is needed to reduce surges in hospitalizations and prevent morbidity and mortality from COVID-19," the authors of the Indiana study said.