Coronavirus science | Week in review: Latest on masks, smoking, and immunity



READ | Valve masks don't slow the spread of the Covid-19 virus - and here's the science to back it up

The Covid-19 pandemic has brought in its wake the compulsory use of face masks as they help to limit the spread of SARS-CoV-2.

Masks with exhalation valves, however, do not slow the spread of the virus, a researcher from the National Institute of Standards and Technology (NIST) has found.

The videos, which show airflow patterns through masks with and without exhalation valves, were created by NIST research engineer Matthew Staymates and were published, along with an accompanying research article, in the journal Physics of Fluids.

"When you compare the videos side by side, the difference is striking," Staymates said in a news release by NIST.

"These videos show how the valves allow air to leave the mask without filtering it, which defeats the purpose of the mask."

Exhalation valves make breathing more comfortable for the wearer. This type of mask is commonly worn by construction workers exposed to huge amounts of dust, or by hospital workers.

READ | Exercising while wearing your face mask on is not dangerous, researchers say

Since a face mask is supposed to cover the mouth and nose in order to limit the spread of the new coronavirus, wearing one while exercising is uncomfortable for most people.

However, contrary to previous findings that wearing a mask during exercising impairs oxygen intake – as well as the World Health Organization's official advice, stating that “people should NOT wear masks while exercising, as masks may reduce the ability to breathe comfortably" – a new study suggests that this isn’t the case.

According to the researchers who looked at the effects of face masks on the cardiorespiratory system (the heart, blood vessels, and lungs) during physical activity, most people should be able to breathe perfectly well with a mask on while exercising, despite it not feeling comfortable.

"There might be a perceived greater effort with activity, but the effects of wearing a mask on the work of breathing, on gases like oxygen and CO2 in blood or other physiological parameters, are small, often too small to be detected," study author and exercise physiologist, Susan Hopkins from the University of California San Diego (UCSD), said in a news release by the university.

The findings were published in the Annals of the American Thoracic Society.

For their study, Hopkins and colleagues reviewed existing scientific literature on the effects of different face masks, including surgical masks, N95 respirators, and cloth face masks, on cardiorespiratory response during physical activity.

READ | Case study: Allergens that cause common skin condition found in masks

Cloth face masks have been used as a key tool in the fight against SARS-CoV-2, the virus that causes Covid-19. However, one 60-year-old man ended up in the emergency room (ER) because of his mask.

At this year’s virtual American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting, doctors delivered a report on the case.

"We treated a 60-year-old Black man with adult-onset eczema, contact dermatitis and chronic nasal allergies in our clinic after he presented three times to our hospital emergency room (ER) because of an uncomfortable face rash," allergist Yashu Dhamija, MD, ACAAI member and lead author of the paper, said.

"Up until April 2020, his skin conditions had been under control, but with mask-wearing, his symptoms began occurring in areas that providers were not yet accustomed to."

Their report was published in the journal Annals of Allergy, Asthma & Immunology.

Contact dermatitis, Health24 explains, is an acute or chronic inflammation caused by skin contact with certain substances.

READ | SEE | Smoking worsens Covid-19 infection in the airways, new study reveals

Since the early days of the pandemic, questions have been raised about the link between smoking and Covid-19, the disease caused by SARS-CoV-2.

In June this year, the World Health Organization stated that, based on existing literature assessing the association between smoking and Covid-19, there was “insufficient information to confirm any link between tobacco or nicotine in the prevention or treatment of Covid-19”.

However, more recent studies have shown that while smokers are not at risk of contracting infection, their risk of severe disease and death, once infected, is higher than that of non-smokers, although the ways that cigarette smoke exposure affects airway cell infection by SARS-CoV-2 have not been very clear.

A new study by scientists at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at the University of California has helped understand how this happens by investigating SARS-CoV-2 infection on a cellular and molecular level – using a model of airway tissue created from human cells.

Their report was published in Cell Stem Cell.

To perform their study, the scientists employed a platform known as an air-liquid interface culture. Essentially, this is grown from human airway stem cells and closely replicates how the airways behave and function in humans.

READ | Coronavirus immunity: Promising news from latest research

Scientists have been scurrying to understand immunity against reinfection with SARS-CoV-2 (the virus that can lead to Covid-19).

It is still not entirely clear how long contracting the virus confers immunity, with early studies suggesting a period of a few months, which, therefore, means that it may only provide temporary protection against reinfection.

One of these studies, for instance, found that antibody levels "waned quite rapidly" after infection in the British population, suggesting a risk of multiple infections, Health24 reported.

However, newer studies indicate immunity could last longer.

According to a study published in the renowned journal Nature Medicine, people who have recovered from Covid-19 have powerful and protective killer immune cells, even when antibodies are not detectable.

This, the authors wrote, “represents major determinants of immune protection on an individual as well as population level”.


SA cases update: 

The latest number of confirmed cases is 767 679.

According to the latest update, 20 903 deaths have been recorded in the country.

There have been 710 099 recoveries.

So far, more than more than 5.29 million tests have been conducted, with 21 904 new tests reported.

Global cases update:

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

Early on Monday morning, positive cases worldwide were more than 58.5 million, while deaths were more than 1.38 million.

The United States had the most cases in the world - more than 12.2 million, as well as the most deaths - more than 256 000.

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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