Study shows blood oxygen level could help predict which patients will eventually need basic oxygen support and which will require advanced oxygen therapy. Here are the recent developments in coronavirus science:
The following is a 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.
Oxygen level while walking identifies at-risk patients
It can be helpful to assess blood oxygen levels in patients when they are walking if that level is normal when they are sitting, a new study suggests. A low level of oxygen in the blood, or hypoxia, contributes to shortness of breath and worsening illness in patients with Covid-19.
At 10 Chicago-area hospitals, doctors studied 531 Covid-19 patients whose blood oxygen levels were normal at rest. Roughly one in four developed hypoxia when they got up and walked.
These individuals were nearly five times more likely to eventually need basic oxygen support and nearly eight times more likely to need advanced oxygen therapy, compared to patients whose blood oxygen levels held steady while walking.
The drop in blood oxygen levels while walking could be detected an average of 12 hours before patients required extra oxygen, researchers found.
So-called ambulatory hypoxia "may serve as an early, non-invasive physiologic marker for the likelihood of developing moderate to severe disease and help clinicians triage patients and initiate earlier interventions," the researchers proposed in a paper posted on Thursday on medRxiv ahead of peer review.
Cancer patients should get vaccine priority
Cancer patients who get Covid-19 are at high risk for poor outcomes and should be considered for priority access to coronavirus vaccines, according to The American Association for Cancer Research Covid-19 and Cancer Task Force.
The task force reviewed available data on fatality rates of patients with cancer who developed Covid-19 and based their recommendation on 28 publications. Their position paper was published on Saturday in the journal Cancer Discovery.
A separate Italian study reiterated that fear of infection should not be a reason to delay cancer treatments. Among nearly 60,000 cancer patients treated early this year in Italy, fewer than 1 percent developed Covid-19, they reported on Thursday in JAMA Oncology.
Early reports from China indicated a much higher risk of contracting Covid-19 among patients getting cancer therapy, Dr Carlo Aschele of Ospedale Sant'Andrea in La Spezia told Reuters. "In Italy, oncologists, and patients as well, were terrified, expecting to face a huge amount of infections and death, particularly among patients receiving chemo or immunotherapy," he said.
The reassuring results will allow oncologists and patients to make informed decisions regarding anti-tumour treatment during this pandemic, he added.
EU regulators urge caution for vaccines, treatments in pregnant women
The European Medicines Agency said on Monday that the Covid-19 vaccine developed by Pfizer Inc and BioNTech SE should only be given during pregnancy "on a case by case basis" because there are not enough data yet on the potential risks to pregnant women.
The US Centers for Disease Control and Prevention (CDC) had already acknowledged the issue on its website. It advises that "getting vaccinated is a personal choice for people who are pregnant."
There is also a lack of data for Covid-19 treatments in pregnant women, according to a paper published on Wednesday in The Lancet Global Health. Researchers who reviewed clinical trial registries found that of 722 Covid-19 treatment studies, 538 (75 percent) specifically excluded pregnant women.
"Without explicit and proactive efforts to recruit and retain pregnant women in therapeutic trials for Covid-19, expectant mothers will suffer from having fewer medical options available to them, because we are not including them in clinical trials," coauthor Dr Melanie Taylor from the World Health Organization and CDC said in a statement. "There is a very real possibility that treatment (for Covid-19) could become approved ... without evidence-based guidance for use in pregnant women."
Low reinfection risk for those who test positive for antibodies
A study of more than three million people adds to evidence that people with Covid-19 antibodies have a significantly lower risk of future infection with the new coronavirus.
Working with healthcare data analytics companies HealthVerity and Action, as well as commercial labs Quest Diagnostics and LabCorp, researchers at the US National Cancer Institute (NCI) had access to results of more than 50 percent of commercial Covid-19 antibody tests conducted in the United States through August.
Overall, 11.6 percent of the tests were antibody-positive. When researchers looked at study subjects who returned to the labs for repeated tests, they found people who were antibody-positive on the first test had a roughly 10-fold lower risk of having evidence of new infection compared to people with a negative first test.
"This finding suggests that people who have a positive antibody test result ... have significant immunity to SARS-CoV-2 and are at lower risk for future infection," said the NCI's Dr Norman Sharpless. His team's report was posted on medRxiv on Sunday ahead of peer review.
Covid-19 far more deadly than seasonal flu
Covid-19 is three times more deadly than seasonal influenza, according to researchers in France who compared 89,530 patients hospitalised with Covid-19 early this year with 45,819 patients hospitalised with flu between December 2018 and February 2019.
The death rate was 16.9 percent vs 5.8 percent, which is "particularly striking when reminded that the 2018/2019 flu season had been the worst in the past five years in France in terms of number of deaths," Dr Catherine Quantin, from Dijon University Hospital, said in a news release.
More patients with Covid-19 landed in intensive care units (16.3 percent vs 10.8 percent) and the average ICU stay was nearly twice as long (15 days vs 8 days), her team reported on Thursday in The Lancet Respiratory Medicine.
Covid-19 patients were also more likely to need mechanical ventilation and to suffer lung failure.
In another study published on Wednesday in The BMJ, US researchers found people being hospitalised for Covid-19 carried higher risks of organ failure and death, and increased health resource use, compared to people hospitalised for the flu.
Oxygen-monitoring devices less reliable in Black patients
Covid-19 can cause blood oxygen levels to fall to dangerously low levels, and devices used to monitor these levels are far less reliable in Black patients than in white patients, a large study found. So-called pulse oximeters clip onto a fingertip and pass red and infrared light through the skin to gauge oxygen levels in the blood, which darkens when levels drop.
Because pulse oximeters were mostly tested on whites when they were developed, they are calibrated for people with light skin.
Among 1,609 patients studied this year at the University of Michigan Hospital in Ann Arbor, the devices missed low oxygen levels in 11.7 percent of Black patients compared to 3.6 percent of white patients. When the researchers studied another 8,392 patients treated at 178 intensive-care units in 2014-2015, they found pulse oximeters missed low oxygen levels in 17 percent of Blacks versus 6.2 percent of whites.
"Given the widespread use of pulse oximetry for medical decision-making, these findings have some major implications, especially during the current Covid-19 pandemic," the researchers warned on Wednesday in The New England Journal of Medicine. "Reliance on pulse oximetry to triage patients and adjust supplemental oxygen levels may place Black patients at increased risk."
Minority Covid-19 patients may benefit from tocilizumab
Among mostly non-white patients hospitalised with Covid-19 pneumonia, Roche's arthritis drug Actemra, also known as tocilizumab, reduced the odds of needing mechanical ventilation or dying.
Among the 389 volunteers in a study, the combined risk of those events was 12 percent in patients randomly assigned to receive tocilizumab in addition to standard care, versus 19 percent in those who received a placebo.
Looking only at the risk of death, however, rates in the two groups were similar, researchers reported on Thursday in The New England Journal of Medicine. Tocilizumab also did not hasten patients' discharge from the hospital or the time it took for their medical status to improve.
Previous studies did not focus on racial or ethnic minorities and yielded mixed results. Earlier this month, a different team of doctors reported that the drug reduced patients' risk of dying in the hospital, but the difference was not statistically significant.
The Infectious Diseases Society of America currently does not recommend routine use of tocilizumab in hospitalised patients.