advertisement

Infectious Diseases

28 September 2020

Coronavirus research recap: 'Silent spreaders', severe infections, and blood tests

‘Silent spreaders’ may be carrying the same amount of virus as those with symptoms; and what experts have learned, and the questions that remain about severe infections.

LATEST SCIENCE AND RESEARCH

READ | ‘Silent spreaders’ may be carrying the same amount of virus as those with symptoms  

The true extent of asymptomatic spread of SARS-CoV-2, the virus that causes Covid-19 disease, is still unknown.

In June, a news update by the World Health Organization (WHO) stated that current evidence from contact tracing suggests that asymptomatic (displaying no symptoms) infected individuals are much less likely to transmit the virus than those who develop symptoms.

However, a more recent study, published this month in the journal Thorax, found that people with "silent" Covid-19 infection have as much of the virus in their noses and throats as those with symptoms.

A second study, also published this month in PLOS Medicine, found that while the majority of infected individuals do develop symptoms, they may test positive for the virus before those symptoms appear.

READ | What experts have learned, and the questions that remain about severe Covid-19-infections 

For months, scientists have been trying to understand the new coronavirus, SARS-CoV-2, and Covid-19 disease caused by the virus.

Based on intensive research since the outbreak in central China late last year, we know that the virus behaves differently compared to similar pathogens. But although the understanding of Covid-19 disease has made great progress, many questions still remain.

In a recently published editorial, three researchers review current information about the management of patients with the acute respiratory distress syndrome (ARDS) that may be experienced by patients with severe Covid-19. They also explore what has been learned about the treatment of Covid-19 patients, and look at the gaps in knowledge that warrant further research.

ARDS is a rapidly progressive disease in critically ill patients, where the patient’s lungs cannot supply enough oxygen to their vital organs. Patients with ARDS are usually placed on ventilators.

The condition has been seen to develop in many patients with severe Covid-19. A systemic review and meta-analysis that was submitted to the Bulletin of the World Health Organization (WHO) earlier this year explained that the prevalence of mortality among patients with comorbidities and advanced age was very high, with ARDS, “the most likely independent predictor of in-hospital mortality”.  

READ | Blood test could spot those at highest risk for severe Covid-19 

If you're unfortunate enough to be admitted to the hospital with Covid-19, a common blood marker may predict how severe your illness might become, new research shows.

The blood marker is called "red cell distribution width" (RDW) – basically, the greater the variance in the size of red blood cells, the poorer a patient's prognosis, the study authors explained.

A Covid-19 patient's RDW test result "was highly correlated with patient mortality, and the correlation persisted when controlling for other identified risk factors like patient age, some other lab tests and some pre-existing illnesses," said study co-author Dr Jonathan Carlson, of Massachusetts General Hospital (MGH) in Boston.

The new study was published online on 23 September in JAMA Network Open and was led by Dr John Higgins, a pathologist investigator at the hospital and associate professor of systems biology at Harvard Medical School.

READ | Could zinc help fight Covid-19?

Millions of people pop zinc supplements at the first sign of the common cold. Now, new research suggests the nutrient might play a role in Covid-19 outcomes, too.

Researchers from Spain reporting at a European coronavirus conference found that hospitalised Covid-19 patients with low blood levels of zinc tended to fare worse than those with healthier levels.

"Lower zinc levels at admission correlate with higher inflammation in the course of infection and poorer outcome," said a team led by Dr Roberto Guerri-Fernandez of the Hospital Del Mar in Barcelona.

One expert in the United States said the finding makes intuitive sense.

"It has long been thought that zinc bolsters the immune system," said pulmonologist Dr Len Horovitz, of Lenox Hill Hospital in New York City. "A possible explanation in this study is that zinc may have an anti-inflammatory effect that is protective."

In the new study, Guerri-Fernandez's team tracked medical outcomes against the results of lab tests for 249 patients admitted to the hospital with Covid-19 in March and April. Patients averaged 63 years of age and 21 (8%) died from their illness.

CORONAVIRUS CASES LATEST

SA cases update: 

The latest number of confirmed cases is 670 766.

According to the latest update, 16 398 deaths have been recorded in the country.

There have been 603 721 recoveries.

So far, more than more than 4.14 million tests have been conducted, with 15 028 new tests reported.

Global cases update:

For the latest global data, follow this interactive map from Johns Hopkins University & Medicine.

Late on Sunday night, positive cases worldwide were almost 32 million, while deaths were more than 995 000.

The United States had the most cases in the world - over 7 million, as well as the most deaths - more than 204 000.

WHAT'S HAPPENING IN THE REST OF THE WORLD 

Latest news:

HEALTH TIPS (as recommended by the NICD and WHO)

• Maintain physical distancing – stay at least one metre away from somebody who is coughing or sneezing

• Practise frequent hand-washing, especially after direct contact with ill people or their environment

• Avoid touching your eyes, nose and mouth, as your hands touch many surfaces and could potentially transfer the virus

• Practise respiratory hygiene – cover your mouth with your bent elbow or tissue when you cough or sneeze. Remember to dispose the tissue immediately after use.

Image credit: Getty Images