As the coronavirus, SARS-CoV-2, continues to spread and as the illness it causes, COVID-19, runs rampant, what can you do to stay safe? How does the virus spread? How can you avoid a superspreader? Should you wear a mask and, if so, which one? Should you go for antibody testing?
The coronavirus spreads by respiratory droplets or aerosols. Every time we sneeze or cough or even speak we emit respiratory droplets. If a person is infected, the coronavirus is carried in these respiratory droplets and can spread to another person. The density of the virus in the air and the amount of time one is exposed to the aerosols are significant factors determining whether one becomes infected. An emergency medical technician riding in an ambulance with a sick, coughing patient or a nurse in a closed room with a patient who is short of breath are both at high risk for infection. On the other hand, passing an afflicted person on the street is much less likely to cause an infection. Coronavirus can live on surfaces and cause infection but surface contamination and fleeting encounters are much less worrisome than close, person-to-person exposure for prolonged periods. No one knows the minimum amount of contact, one guideline is 10 minutes or more spent with an infected person, but the longer the contact, the greater the chance of infection.
As more is learned about the virus’s spread, it is becoming clear that superspreader events play a significant role. Superspreader incidents occur when one person infects a large number of other individuals. These events occur where large numbers of people are present, with close contact between people and in confined spaces with poor ventilation. Superspreader incidents have occurred in nursing homes, churches, manufacturing plants, schools, conferences, gyms, clubs, bars, prisons and ships. It is estimated that 10-20 percent of infected people are responsible for about 80 percent of cases. The reason for this is that many infected people do not have symptoms, so they do not know they are transmitting the disease. If an asymptomatic person shows up at a large, indoor gathering the stage is set for a superspreader event. Stopping superspreader incidents would go a long way toward controlling the coronavirus’s spread.
Since coronavirus is predominantly spread by respiratory droplets and due to the high number of asymptomatic spreaders, it would make sense that wearing a mask could reduce the risk of infection. The theory is that a mask can prevent transmission of the virus from an infected person by trapping droplets from breathing or coughing and not allowing them to permeate into the environment. However, there is scant data on masks, especially in the community setting. There are several types of masks including cloth masks, surgical masks and respirators. N95 respirators are the highest form of protection. The N95 blocks 95% of small airborne particles (the 95% blocking ability is where it derives its name). There are two types of N95 respirators: N95 is the US standard and KN95 is the Chinese name; the two are nearly equivalent. N95 users must undergo stringent testing to ensure a tight seal around the mask and make sure there is no leakage. N95 respirators are used for close contact and recommended for health care workers. Due to worldwide shortage, these masks are not available for use in the community. Surgical masks trap the wearer’s secretions and block 10 to 90 percent of particles. Cloth masks can block particles as well. Cloth masks with a water resistant fabric, multiple layers and good fit around the face are better than single layer choices (such as a scarf or bandana). Neither surgical nor cloth masks require special fitting and both may be useful in the community setting (although not necessary when at home unless a household member is infected). Can the use of a mask reduce the risk of coronavirus spread? One study in the health care setting showed that N95 respirators were 96% effective at reducing infection while surgical masks were 67% effective. The data for masks is lacking in the community, but starting to accumulate. One study showed the rate of infection was less in US states that mandated the use of face masks compared to states that did not require masks. Many Asian countries were able to control the epidemic by near universal mask wearing (90% wear masks) and social distancing. For example, Hong Kong, a densely packed city of 7.5 million had only six deaths due to COVID due to a 97% compliance with wearing masks. In April there were conflicting messages from government agencies regarding wearing face masks. Now the evidence seems to be firmly in favor of masks to prevent spread. Besides, there are no risks to wearing a mask (and no medical contraindications).
Would widespread testing slow the rate of infection? There are two types of tests for the coronavirus. The PCR (polymerase chain reaction) test detects whether the virus is present on a nasal or throat swab. It can determine if the virus is present with reasonable efficacy but there is a high false negative rate (the test comes out negative, but the person has the infection). Because of that, if a patient has suspicious symptoms but a negative test, one or two more follow up tests are needed (and must come back negative) to rule out coronavirus. The PCR test is good if someone has been exposed to a person with COVID or if they have symptoms. The results can be used to quarantine and contain the virus. Antibody testing requires drawing blood and reflects the body’s immune response to the virus, rather than detecting the virus itself. The antibody test looks at two parts of the immune response. If the test is positive for IgM it means that the infection is still active. If the test shows that IgG is positive, it means there was a previous infection. Unfortunately, there are problems with the antibody tests. Patients with no or mild symptoms may not mount an immune response and the test may be negative. In addition, the test may be negative within the first 14 days after the onset of symptoms. Lastly, the antibodies seem to fade after a few months. Due to these issues, widespread antibody testing is not recommended at this time. Even if the test shows immunity, the patient must still wear a mask and practice social distancing.
Therefore, to cover your COVID concerns and control the coronavirus catastrophe, remember to avoid the 3 C’s: Closed spaces, Crowded places, and Close contact settings. How do you know if a place is too crowded? People noise may be a good marker for an indoor gathering. The more noise you hear, the more dangerous the space. In addition, if you wish to wean the worst of the pandemic, do the 3 W’s: Wear a mask, Watch your distance and Wash your hands.
