Coronavirus research recap: Superspreader on a bus, who's most at risk, and damage to the heart

LATEST SCIENCE AND RESEARCH

READ | Study finds coronavirus superspreader infected more than 20 people on one bus

On 19 January 2020, early in the Covid-19 outbreak, 67 Buddhist passengers and a driver boarded a bus in Ningbo, China, unaware of the risk of getting ill. Since Covid-19 was so new, no-one was wearing a mask.

But days later, 24 people who had been on the bus fell ill. A new study published in JAMA Internal Medicine shows that it took only one person infected with coronavirus to spread the virus to more than a third of the passengers during a trip that took one hour and 40 minutes.

According to the study, the infected person boarding the bus was not showing any symptoms, but had been in contact with four people from the Hubei province, where the virus had been spreading rapidly.

Hours after the bus ride, the infected person developed a cough, chills, aches and pains – and tested positive for SARS-CoV-2 a few days later. In the meantime, several other passengers had also developed symptoms, and tested positive.

This incident occurred early in the outbreak when the wearing of masks wasn't yet enforced – and demonstrates clearly that the 2m physical distancing rule has little effect in enclosed spaces with restricted ventilation like buses and other modes of public transport.

READ | The Covid-19 virus is deadliest if you are older and male - scientists looked at the risks

A new analysis looking into the mortality risk for Covid-19, the disease caused by SARS-CoV-2, shows that out of 1 000 people under the age of 50 who are infected with the virus, almost none will die.

However, for those in their fifties and early sixties, about five will die, with men at greater risk than women. And for every 1 000 people in their mid-seventies or older who are infected, around 116 will die.

The research team, whose analysis was published in preprint server medRxiv, and has not yet been peer-reviewed, looked at the presence of antibodies against SARS-CoV-2 in people in several countries, including England and Spain, following the first peak of the pandemic.

The role of antibodies in protection against Covid-19 and the length of time survivors will be protected against reinfection have been studied for months.

Using data from antibody-prevalence studies, the team estimated mortality risk by age. In June and July, thousands of people across England received a pinprick antibody test in the post.

The team stated that of the 109 000 randomly selected teenagers and adults who took the test, around 6% harboured antibodies against the virus. This result was then used to calculate an overall infection fertility ratio (IFR) for England of 0.9% (or 9 deaths in every 1 000 cases).

READ | What Covid-19 is doing to the heart, even after recovery

A growing number of studies suggest many Covid-19 survivors experience some type of heart damage, even if they didn't have underlying heart disease and weren't sick enough to be hospitalised. This latest twist has health care experts worried about a potential increase in heart failure.

"Very early into the pandemic, it was clear that many patients who were hospitalised were showing evidence of cardiac injury," said Dr Gregg Fonarow, chief of the division of cardiology at the University of California, Los Angeles. "More recently, there is recognition that even some of those Covid-19 patients not hospitalised are experiencing cardiac injury. This raises concerns that there may be individuals who get through the initial infection, but are left with cardiovascular damage and complications."

Fonarow said these complications, such as myocarditis, an inflammation of the heart muscle, could lead to an increase in heart failure down the road. He's also concerned about people with pre-existing heart disease who don't have Covid-19 but who avoid coming into the hospital with heart problems out of fear of being exposed to the virus.

"The late consequences of that could be an increase in heart failure," he said. "It is much safer if having symptoms that could represent heart attack or stroke, to come into the emergency department than to try to ride it out at home."

Nearly one-fourth of those hospitalised with Covid-19 have been diagnosed with cardiovascular complications, which have been shown to contribute to roughly 40% of all Covid-19-related deaths.

But two recent studies suggest heart damage among those infected may be more widespread. In JAMA Cardiology, an analysis of autopsies done on 39 Covid-19 patients identified infections in the hearts of patients who had not been diagnosed with cardiovascular issues while they were ill.

READ | Can Covid-19 cause diabetes?

A Covid-19 infection can cause a lot of serious, sometimes lingering health problems, like lung damage, kidney damage and ongoing heart issues. Lately, research has suggested it may also cause the sudden onset of insulin-dependent diabetes.

A new report details the case of a 19-year-old German with asymptomatic Covid-19 infection who ended up hospitalised with a new case of insulin-dependent diabetes.

Five to seven weeks before his diabetes developed, the young man's parents developed Covid-19 symptoms after an Austrian ski trip. Eventually, the entire family was tested. Both parents tested positive for Covid-19 antibodies, as did the 19-year-old, indicating all had been infected with the coronavirus. However, the son had never had symptoms of the infection.

When the 19-year-old was admitted to the hospital, he was exhausted, had lost more than 26 pounds in a few weeks, was urinating frequently and had left-sided flank pain. His blood sugar level was over 550 milligrams per deciliter (mg/dL) – a normal level is less than 140 mg/dL on a random blood test.

Doctors suspected he had type 1 diabetes. He tested positive for a genetic variant that is rarely associated with type 1 diabetes, but not genetic variants commonly present in type 1. He also didn't have antibodies that people with type 1 diabetes usually have at diagnosis. 

CORONAVIRUS CASES LATEST

SA cases update: 

The latest number of confirmed cases is 638 517.

According to the latest update, 14 889 deaths have been recorded in the country.

There have been 563 891 recoveries.

So far, more than 3.8 million tests have been conducted, with 16 367 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 27 million, while deaths were close to 881 000.

The United States had the most cases in the world - over 6.2 million, as well as the most deaths - more than 188 000.

WHAT'S HAPPENING IN THE REST OF THE WORLD 

Latest news: 

READ | India tops four million virus cases as pandemic rages 

India has become the third country to pass four million coronavirus infections, setting a new record daily surge in cases on Saturday as the pandemic showed no sign of peaking.

The new cases took India to 4 023 179 infections, third behind the United States which has more than 6.3 million and just trailing Brazil on 4.1 million.

The growing caseload comes after the World Health Organization said it did not expect widespread immunisation against Covid-19 until mid-2021.

The WHO also ruled out endorsing a vaccine that has not been proven safe and effective, over concerns around the rush to develop a jab for the virus.

As governments around the world enforce measures to slow the virus, police in Australia - which has reported 26 200 cases and 748 deaths - arrested more than a dozen protesters in Melbourne on Saturday for deliberately flouting the city's stay-at-home orders.

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

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