How Will We Go Back to âNormalâ?
May 1, 2020, noon â COVID-19, the disease caused by the SARS-CoV-2 virus, has disrupted life as we know it for communities around the world. While the human population is constantly under attack from myriad respiratory infections, SARS-CoV-2 is unique for several reasons. First and foremost, the virus â normally found in animal species, such as bats â was introduced into humans in late-2019, meaning that all 7.8 billion people on Earth are susceptible to infection. Second, the virus is easily spread from person to person, mainly through droplets and to a lesser extent, via fomites (contaminated objects or surfaces), which can lead to infection. Third, COVID-19 can cause severe illness in approximately 20 percent of infections and kill 1 to 3 percent of those infected overall. Older persons (age 65-plus) or individuals with underlying conditions such as obesity, compromised immune systems, and diseases of the heart, lungs, liver or kidneys have a much higher risk of severe illness. Unless patients with severe disease are hospitalized and given intensive assistance to breathe until they recover, many will die. The best way to minimize mortality from COVID-19 is to keep the number of cases at any one time low enough for health care systems to provide the appropriate level of care for every critically ill patient, so-called âflattening the curve.â
How to stop the spread of COVID-19
At this time, the only potentially effective vaccines against the virus are undergoing clinical trials that are not expected to end until late-2020 to early-2021. Until a vaccine is available and administered to those at highest risk of infection or severe disease, other measures are needed to slow the spread of the virus. This is the objective of social distancing. The goal of social distancing is to keep people far enough apart that any virus shed by an infected person will not enter the respiratory tract of susceptible individuals, causing them to become infected.
The primary way SARS-CoV-2 appears to spread is person-to-person via droplets sprayed into the air by coughing and sneezing. These droplets tend to travel a few feet and fall to the ground, so staying at least 6 feet away from an infected person should prevent exposure to the virus. While there is evidence that virus-containing droplets small enough to hang in the air for several hours, called aerosols, can occur, this has not been observed to be a major means of transmission. The virus can also survive on surfaces. If touched, the virus may be picked up and transferred by contaminated hands to the nose, mouth and eyes of a susceptible individual, causing them to become infected.
How long the virus survives on surfaces depends upon the material that is contaminated. Studies have shown that the virus can persist on cardboard for up to one day, and on plastic and stainless steel for up to three days. While much attention has focused on disinfecting food and other products coming into homes, it is unlikely that contamination by touching plays a major role in the spread of infection.
Moreover, there has been an increase in gastrointestinal illnesses and poisonings due to human ingestion of cleaning products in an effort to avoid this possible route of transmission. The most effective method of reducing risk from touching surfaces that may harbor virus is to frequently wash your hands. Disinfecting surfaces like doorknobs and countertops is prudent. Â Wash fresh fruits and vegetables with running water so that you donât ingest harmful detergents. Again, and we canât emphasize this enough: frequent handwashing can slow the spread of COVID-19.
How to maintain social distance
The most effective way to prevent susceptible persons from coming in contact with the virus in the air or on contaminated surfaces is by everyone staying at home. That was the reason the COVID-19 pandemic was declared a national emergency and state and local health authorities issued stay-at-home orders. While effective, some people are required to work because their jobs are considered essential â for example health care workers, market employees, first responders and law enforcement personnel â and most people need to leave home occasionally for critical necessities, such as shopping for food, caring for others and seeking medical care.
When it is necessary to leave home, there are two ways to socially distance from others. The first is to stay at least six feet away from other people (physical distance). The second is to wear a face covering. Covering the nose and mouth with a mask can serve two purposes: One is to prevent airborne virus from being inhaled by a person who is susceptible to the infection; the other is to prevent infected individuals from spreading the virus.
Since the virus can be shed for one to two days before symptoms develop in an infected person, and some infected individuals have no or only mild symptoms, the Centers for Disease Control and Prevention now recommends that everyone wear a face covering when they are in public, regardless of symptoms.
N95 respirator masks: filter particles down to the size of a single virus. They are used in health care settings to protect workers who perform procedures that create large amounts of these very small particles. N95 masks are designed to protect the wearer from inhaling particles and pathogens and fit tightly around the face. There is a global shortage of these respirators and should be reserved for health care providers and first responders to protect them from becoming infected.
Surgical masks: filter larger particles, such as droplets that are created by coughing and sneezing. This is the type of mask typically worn by personnel in medical and dental offices to prevent the wearer from exposing patients to infectious pathogens. They also offer some protection to the wearer by preventing inhalation of most virus-containing droplets. Although they are made of material similar to an N95 mask, they are not designed to fit as tightly around the face, making them more comfortable to wear but also less effective at blocking aerosolized virus.
Cloth masks: capture droplets created by coughing and sneezing. They can be made from a variety of materials using one or more layers of common fabric found in the home. Their ability to capture infectious droplets depends on the type of material and the number of layers used to make the mask.
Testing and tracing: What else we must do to limit the spread of COVID-19
There are basically two types of tests for COVID-19. One is used to look for the virus in a sample taken from a swab of the patientâs nose or throat. This test detects whether the patient is currently infected and capable of spreading the virus to others regardless of whether symptoms are present. The other kind of test is used to detect proteins in a patientâs blood called antibodies that their immune system produces to fight the virus. Detecting antibodies indicates that an individual was infected with SARS-CoV-2 but cannot determine whether the individual is currently infected and can transmit the virus to others. Also, it takes several days from the time an individual is infected until resulting antibodies can be detected in the blood. So an antibody test result may be negative even though the patient has symptoms and has the virus.
Both the viral test and the antibody test might be necessary to determine an individualâs infection status. Since antibodies remain in the blood for months and potentially years after recovering from COVID-19, antibody tests will be important for determining who has already been infected with SARS-CoV-2 and could potentially stop social distancing. However, we donât yet know whether the presence of antibodies truly confers protection against re-infection and if it does, for how long. Much will be learned about this in the coming weeks and months by studying people with positive antibody tests.
Contact Tracing is a central tenant of infectious disease control, which involves identifying infected individuals and contacting everyone they encountered while they were infectious. Contacts are then informed that they could be infected and should self-quarantine by avoiding contact with others for 14 days from the time of last contact with a person known to be infected. This helps ensure they do not spread the virus before they develop symptoms. Any contacts who are found to be infected should stay in isolation until they fully recover from COVID-19, and their contacts should be notified to self-quarantine as well. In a typical week of your life before COVID-19, think about the number of people you interacted with within a six-foot distance. Think about the number of people they interacted with. Imagine contacting each person, testing them and quarantining all of these people and you can start to understand what a massive job that contact tracing will require of all of us, particularly if we stop social distancing while many susceptible people are still present in the population.
However difficult, this is our future. A well-executed combination of contact tracing, testing and social distancing is our best hope for containing SARS-CoV-2 and keeping the number of cases low enough to avoid overwhelming our health care systems. We can do our part by rapidly identifying individuals who are infected, immune or susceptible to infection through widespread testing; by notifying and quarantining potentially infected contacts; and by maintaining social distancing through physical separation and wearing masks. Do all these well and the virus may run out of new hosts before it infects everyone in the community. When a vaccine becomes available, we will be able to increase the proportion of immune community members making it harder for the virus to find a susceptible host and speed up the process of ending the pandemic.
â Richard Garfein, PhD, MPH, professor of epidemiology, and Andrea LaCroix, PhD, professor of epidemiology, both at UC San Diego School of Medicine
