Does the use of masks really reduce the spread of the coronavirus? Experts have different answers.
Editor’s note (June 2, 11.30): The article discussed below was retracted by the Annals of InternalMedicine magazine. The authors wrote that statistical methods cannot determine whether the results are reliable, making the results of the small study “uninterpretable”. The study has shown that surgical and cotton masks do not effectively retain infected droplets containing SARS-CoV2. Subsequent research has suggested that in addition to staying six feet away from other people, face masks are an effective method to prevent the spread of the virus.
For the first time, theCentre of Disease Control andPrevention (Center for Control and Prevention) (CDC) He recommended that healthy individuals wear masks to cover their mouths and noses when going to places where social distance is difficult to maintain. But there is still serious debate about how much masks – especially homemade fabric masks recommended by the CDC for the public – slow the spread of SARS-CoV2, which causes Covid-19.
More meticulously than another, they try to address the usefulness of masks and arrive at different conclusions. One study examined the effect of masks on periodic coronaviruses (causing many common cold cases) and found that surgical masks help sick individuals reduce spreading the virus.
Do Masks Have an Effect on the Spread of the Virus?
However, another study, especially looking at SARS-CoV2, found that neither surgical masks nor fabric masks had any effect on the spread of the virus. However, this study had only four participants, and rough draft measures of virus distribution were used.
The main thing, experts say, is that masks can help people with Covid-19 prevent them from spreading the virus unknowingly. However, the evidence for the benefit of surgical or homemade masks is limited, and masks are not the most important form of protection against the corona virus. May Chu, clinical professor of epidemiology at the Colorado School of Public Health in AnschutzMedicalCampus, who was not involved in either study,
“Wearing a mask doesn’t mean you don’t need to take other measures,” he says. It does not mean that you can approach people, you do not need to wash your hands frequently, and you can touch your face with your hands. All this still needs to be done. The mask is just an extra measure. ”
Face Mask Basic Principles
Advice on masks can easily cause confusion because masks are not made the same. The N95 mask effectively prevents the spread of the virus. When fitted correctly, these masks cover the face properly and filter out microparticles of 0.3 or larger.
But reaching N95 masks is extremely difficult, even for professional healthcare professionals who are exposed to the highest degree of SARS-Cov-2 and need the strongest protection against the virus. In addition, it is extremely difficult to wear these masks correctly. For these reasons, the CDC does not recommend these masks for general use.
Due to the difficulty of procuring, CDC also does not recommend surgical masks to the public. These masks are not leak proof but contain non-woven polyprobieln layers that are moisture resistant. In a surgical mask, 70% of the outside air goes in through the mask and 30% is in the belts, says Chu, so it doesn’t provide as much protection as the N95s.
Due to these shortcomings in surgical and fabric masks, public health officials do not believe that wearing a mask will prevent someone from catching the virus. The airflow follows the path that is least resistant, says RachealJones, an associate professor of family and preventive medicine at the University of Utah, who is not involved in new research.
If there are virus particles around, a surgical and cloth mask would be an extremely convenient route for the virus. And when the fabric is a mask, the person wearing the mask can also carry particles small enough to pass through the fabric.
What if we look at it from the other side?
When the person wearing the mask coughs or sneezes, even if there is a gap in the fabric or on the sides, the mouth covering may be sufficient to contain the initial big condolence. The aim of the new mask studies is whether surgical or fabric masks are helpful enough to control the virus.
Benefits of Face Masks
A study published on April 6 in the journal Annals of Internal Medicine revealed that masks had no benefit. In this study, conducted by South Korean researchers, four patients with Covid-19 were asked to cough into a petri dish 7.8 inches (20 cm) away.
Patients coughed without a mask, while wearing a disposable surgical mask and again while wearing a 100% cotton mask.
It has been observed that neither of them significantly reduces the amount of virus coughed into petri dishes. But experts who contacted Live Science who were not involved in the study were hesitant to rely on the results.
Experts didn’t look beyond 7.8 inches to see if the droplets went farther when people coughed while wearing masks, Chu says. “They didn’t measure 2 or 3 or 4 feet beyond,” he adds.
Study with 426 volunteers
In addition, the study revealed a strange result such that the corona virus tests of the samples taken from the outer surface of the mask were positive and the samples taken from the inner surface were negative. According to Jones, officials think the erratic jets of air from the cough may have carried the virus on the outside of the mask, but disclosure is not very satisfactory.
In another study published in the journal Natural Medicine on April 3, a more detailed method was used to collect virus particles emitted by sick individuals. The researchers asked 426 volunteers to breathe for 30 minutes into a cone-like device that recorded everything that was blown outward.
Of these volunteers, 43 had a flu infection, 54 had a rhinovirus, and 17 had a corona virus (the type that causes the common cold, not the type that causes Covid-19). The method used allowed the researchers to measure how many viruses were present in droplets larger than 0.0002 inches in diameter against aerosol particles of 5 microns or less. Participants in the experiment were randomly participated in the study, both without a mask and with a mask.
The first main finding was that the researchers detected viruses in small particles in all three conditions (influenza infection, rhinovirus, and coronavirus). After collecting and culturing the flu-infected droplets, they discovered that these viruses were contagious.
This is very important, says Ben Cowling, head of the Department of Epidemiology and Biostatistics at the University of Hong Kong, because there has been a long-standing debate among healthcare professionals about whether flu infection is transmitted by airborne aerosols. This study suggests that this is possible and that the common cold can also be transmitted in this way.
“For seasonal coronaviruses and rhinoviruses, we did not attempt to culture the virus into aerosols. But there is no reason to believe the virus will not be contagious, ” Cowling says.
What if we get to the masks?
While surgical masks reduce the amount of virus in the form of droplets released from the sick individual in influenza infection, they did not show the same effect for viruses released in the form of aerosol; In coronavirus, masks reduced viruses released in both droplet and aerosol form;
But it had no effect for viruses released in rhinovirus neither in droplet form nor in aerosol form. For seasons coronavirus, researchers found the virus in droplets in three of ten samples from participants who did not wear masks, and in aerosols in four of the ten samples. No virus was found in either droplets or aerosols in the samples taken from masked people.
The difference between viruses may be related to where these infectious invaders are located in the respiratory tract, says Cowling, Center Co-Director of Infectious Disease Epidemiology and Control Collaboration, WHO * (World Health Organization). For example; While a virus that grows mostly in the nose and throat can be more easily activated in large droplets, a virus that reproduces deep in the lungs may need to travel in smaller particles to allow it to spread to the world.
Results from flu infection and coronavirus suggest that surgical masks can help prevent people with Covid-19 from spreading the virus, Cowling says. SARS-CoV-2 probably behaves similarly to the viruses he and his team worked with, he adds.
In addition, the fact that people can spread the virus even if they do not show symptoms of the disease is a reason to recommend the use of masks to everyone.
But experts still have different views on the usefulness of non-N95 masks.
“To me, there is no harm in wearing these masks, but it doesn’t seem to do much for this study,” says Jones. Samples taken for seasonal coronavirus were small, he says. Especially considering that most of the samples without a mask did not have detectable coronavirus, there was a huge variation in how much people spread the virus, which was not dependent on the mask.
The only point everyone agrees is that the protection afforded by a homemade mask is no less than the protection afforded by a no-go mask. Using masks is recommended for everyone because “any action taken is better than doing nothing,” says Chu. But fabric masks cannot be expected to be as protective as surgical masks, he says. That’s why healthcare professionals warn the public that people should stay at least 6 steps away from each other, even if they wear a mask. In other words, fabric masks are just a tiny part of the control of the COVID-19 outbreak.
“There has been enough research to allow us to say clearly that masks will not stop the spread of the disease, but only have a small effect on the spread of the disease,” Cowling says. “We can’t rely on masks to help us get back to normal.”