Let’s Talk About COVID-19 Prevention
We're now into year two of the pandemic, and we’ve learned a lot about protecting ourselves against the novel coronavirus. Getting vaccinated should be your first priority.
In the early days of COVID-19, many of us quarantined packages and even wiped down our groceries. There was a real concern that COVID-19 transmission could occur by touching contaminated surfaces, so prevention at first focused on hyper-cleanliness, including disinfecting everything in sight. Now, we know so much more about the virus—like how it spreads most commonly through respiratory droplets from close contact with someone who is sick, or via droplets that are “aerosolized," meaning they've gone airborne. So, it’s OK to cool it with all that cleaning (coined "hygiene theater" by the press), according to the Centers for Disease Control and Prevention (CDC). And while it’s always a good thing to wash your hands, today’s preventive tips better control for the main mode of viral spread, including wearing a face mask, maintaining social distancing, and getting vaxxed as soon as you can. These tried-and-true techniques are designed to help you, and others, stay as safe as possible.
Our Pro Panel
We went to some of the nation’s top experts in infectious disease to bring you the most up-to-date information possible.
Amesh A. Adalja, M.D.
Internist specializing in infectious diseases and critical care
University of Pittsburgh Medical Center
Jeanne D. Breen, M.D.
Infectious disease specialist, Assistant Clinical Professor, Laboratory Medicine
Yale School of Medicine
New Haven, CT
John Swartzberg, M.D.
Clinical Professor, Emeritus
UC Berkeley - UCSF Joint Medical Program, Infectious Diseases & Vaccinology Division, UC Berkeley School of Public Health
Experts believe COVID-19 is mainly spread through person-to-person transmission, like when someone sneezes, coughs, or talks within six feet of you. You inhale the droplets they expel; research shows that the virus can become aerosolized and remain suspended in the air for up to three hours after being expelled. You might get it through contact transmission, or touching something with the virus, but increasingly, this route seems less likely.
Possibly, according to Centers for Disease Control and Prevention (CDC) officials, but only with certain masks—for instance, if you’re wearing a cloth mask, wear that over a disposable mask (like a surgical mask), if possible. If you have a legit K95 mask, however, that’s best worn alone. The CDC is still reserving N95 respirators for front-line health care workers, so stick to other mask types if you can. The important thing is to have a mask with a tight fit over your nose and mouth that still allows you to breathe.
Here’s what we know so far: An article from The New England Journal of Medicine found that COVID-19 stays on stuff for varied amounts of time, with various levels of contamination, including copper (four hours), plastic (three days), and stainless steel (three days). Other studies have looked at the larger class of coronaviruses and found they lived on paper for four to five days and certain fabrics up to four days. This is likely true of the novel coronavirus, as well. But it’s important to know that, while this happens in research, we’re still not sure how much this matters IRL, so don’t miss the following FAQ.
By using regular cleaners, like soap and detergent, but not going overboard with the bleach. In fact, the CDC is now saying that cleaning your home, like you probably do already, should be just fine for staying safe against COVID-19 and other nasty germs. You should only use disinfectant against COVID when someone in your home is sick or if someone who is positive for the virus has been in your home within the last 24 hours. Hygiene theater can now officially exit, stage left.
What Is COVID-19, Exactly?
First appearing in the city of Wuhan, China, in December 2019, the novel coronavirus belongs to a family of viruses called “coronaviruses,” which were discovered in the late 1960s. The new disease strain is technically known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The illness that the SARS-CoV-2 virus causes is called COVID-19, named for the year in which this novel virus first emerged.
COVID-19, which to date has infected more than 154 million people around the world and caused 3.2 million confirmed deaths as of early May 2021, can cause mild or severe respiratory symptoms, as well as a range of other health issues. These include symptoms that may replicate the common cold or the flu, ranging from nausea and headaches to diarrhea, as well as the loss of taste or smell (and experts aren't sure if such losses are permanent, or not). Still, as many as 40% of infected people are asymptomatic, meaning they show only mild or even zero signs of illness, yet are capable of transmitting the virus to others. If you think you may have COVID-19, call your doctor ASAP to determine what to do next.
Since this novel virus first appeared on the global stage, turning our personal and professional lives upside-down, COVID-19 has changed, too. It has mutated since it was first detected in Wuhan, and these new strains sometimes cause different and/or more serious disease outcomes. Those changes can impact prevention methods, too. Read on.
What Do I Need to Know About New Strains of COVID-19?
One big challenge to COVID-19 prevention has been how the virus has mutated into what are officially known as variants. New strains like these are a common issue when a virus moves from host to host (i.e., one human to another human, or animal to animal, or even animal to human) because this is when it’s most susceptible to evolutionary change. In other words, the strongest, fittest version of the virus is the one that’s more likely to survive and thrive.
In this case, COVID-19 has developed similar mutations across several variants that show a specific change to the spike protein that can make the virus easier to catch, and, in some cases, might prove to be more difficult to treat. And while scientists aren’t surprised that this has occurred, they are concerned. Because some mutations, like those found in the UK (known as B.1.1.7), Brazil (B.220.127.116.11, or P.1), South Africa (B.1.351), India (B.1.617), and Japan (E484K, nicknamed “Eek”) appear to be more transmissible than the earlier version out of Wuhan. We have a few homegrown U.S. variants too, with documented mutations in California (CAL.20C), Ohio (various strains), and New York City (B.1.526).
Researchers are looking into whether all or any of these new strains are more deadly. They are certainly more likely to cause case counts to rise because they’re much easier to catch, which could lead to hospitals being overwhelmed, leading to higher deaths—it's a matter of math. In fact, the UK variant is up to 70% more transmissible than past COVID strains and is now the dominant strain in the U.S., according to the CDC. And while the UK variant predominates here, all strains listed above been detected in the country.
Another big concern when it comes to preventing COVID-19 is the double mutant coronavirus variant, which has features of the California variant, as well as the Brazil and South Africans variants, too. This new strain has been found in the San Francisco Bay area. We need to know more about this variant and how it affects transmission rates. Researchers don’t yet have the answers, but they are racing to uncover them. And we'll report the facts as soon they become clear.
How Is the Novel Coronavirus Transmitted?
We’ve learned so much about COVID-19 since it was discovered less than two years ago (though it may feel like two centuries ago), and there is still much we don’t know. Yet researchers have made headway into some important areas, like how it’s caught, including through droplet transmission. That means if you’re close to an infected person who coughs, sneezes, or talks, you may inhale droplets carrying mucus or saliva (and, thus, the virus) that is expelled into the air from their mouth, potentially becoming infected yourself. Similarly, if someone with the virus coughs into their hand, and you touch that hand and then touch your own mouth, nose, or eyes, the virus can find its way into your system. This is why wearing a face mask is so important—it can help protect against those droplets from ever being released.
Another key way you can catch it is airborne transmission. This is when small droplets of the virus get into the air and become aerosolized, just hanging there. Meaning, to become infected you don’t have to be anywhere near a person who sneezes, coughs, or talks—you just have to walk into a poorly ventilated space where that person was recently after they've done so. A March 2020 article published in The New England Journal of Medicine found that droplets could be aerosolized for up to three hours. This is yet another reason why mask-wearing has been key to stopping COVID, because wearing one can help protect you from inhaling a large percentage (if not all) of infected, airborne droplets.
Another possible way you might catch COVID—with emphasis on the word possible because the evidence suggests it doesn’t happen all that frequently—is from contact transmission, or when you touch infected surfaces or objects. Studies are ongoing, but several have shown the coronavirus to live on materials like plastic, steel, paper, and cloth for up to four or five days. And COVID-19 may live in feces or urine and potentially transmit that way, if you’re caring for a sick person and come in contact with their waste.
As in many things in life, when it comes to COVID-19 defense is your best offense: The most effective way to stop the spread of this disease is to minimize your odds of catching it in the first place. So, with that…
What About COVID-19 Vaccines?
A wonder of science, we now have not one but three vaccinations against COVID-19 in the U.S.: the mRNA vaccine technology employed by Pfizer-BioNTech and Moderna, and a viral vector vaccine from Johnson & Johnson/Janssen.
These vaccines have shown to be safe and effective, with anyone age 12 or over now eligible in the country to receive their shot, according to the CDC. (Important to know: Only the Pfizer-BioNTech is available for 12 to 15 year-olds, and both the Moderna and J&J vaccines are for people 18 and up.) More good news: It looks like all three vaccines currently available in the U.S. are effective against the new variants, with booster shots a real possibility if a newer mutation proves to make them less effective.
There are even more vaccines available worldwide that aren’t yet approved for use in the U.S., including the AstraZeneca/University of Oxford vax, CoronaVac, and the Sputnik V vaccine. Which is all great news.
Here’s info about the three currently approved in the U.S.:
Pfizer-BioNTech: This vaccine is currently recommended for people 12 years and older. The shot is given in two doses, ideally 21 days apart, in your upper arm. In clinical trials of this vax, it was 95% effective at preventing laboratory-confirmed COVID-19 illness in those without evidence of previous infection. You’re considered fully vaccinated two weeks after the second dose of this shot.
It has common side effects including pain, swelling, and/or redness at or near the injection site; fever; chills; tiredness; and headache, too. But side effects—which not everyone gets!—can be considered to be a good thing, a signal that your body’s immune system is responding to the vaccine and developing immunity against the virus—the whole point of getting one. (But please note: If you don't feel much of anything after your shot, don't freak out. This doesn't mean your immune system, or the vaccine, isn't working. Plenty of folks, particularly men, report few to no side effects, even after the second dose, which at least anecdotally seems to trigger more post-vax symptoms. Your response is unique, based on your individual immune system.) Since a (very) few allergic responses have been reported to this vaccination, you’re typically watched for 15 minutes after having it—30 minutes if you have a history of allergies—just to be on the safe side. But try not to worry. Such reactions are exceedingly rare.
Moderna: Currently recommended for people 18 years and older, this shot is given in two doses, about 28 days apart, in your upper arm. It’s currently being studied in children ages 6 months to less than 12 years old (the first vaccine being considered for this younger age group).
In the company’s application for authorization in late 2020, immunization had a protection rate of 51% at two weeks after the first dose and 94% at two weeks after the second dose. You’re also considered fully vaccinated two weeks after the second dose. It has shown to produce potential, similar side effects to the Pfizer-BioNTech vaccine, for similar reasons—with a similar allergy profile.
Johnson & Johnson/Janssen: Currently recommended for people 18 years and older, this shot is given in a single dose—one and done!—in your upper arm. You might have heard about very rare blood clots and low levels of blood platelets associated with this vaccine—it was “paused” in the U.S. for a brief time in April while the CDC and the U.S Food and Drug Administration (FDA) reviewed results. After careful analysis, both agencies gave the green light for the vaccination to be administered again, effective immediately, with a warning to women 50 and under that they may be at higher risk for this very rare complication. You’re considered fully vaccinated with this shot two weeks after the single dose.
The company’s Phase 3 ENSEMBLE study shows the vaccine was 85% effective in preventing severe disease across all regions studied, and provided protection against COVID-19 related hospitalization and death 28 days after vaccination. The study was conducted in eight countries across three continents. It also found that at 28 days post-vaccination, the level of protection against moderate to severe COVID-19 infection was 72% in the U.S., 66% in Latin America, and 57% in South Africa. Side effects were mild-to-moderate and included fatigue, headache, muscle pain and muscle ache, and injection site pain.
Top 10 Ways to Protect Yourself From COVID-19
Employ these strategies to keep yourself as safe as possible during this global pandemic:
1. Get vaccinated. First and foremost, don’t hesitate, don’t buy into the false fear tactics found online, and do listen to the immunologists and researchers who devote their lives to studying infectious diseases. Unless your doctor advises otherwise, get your shot as soon as you are eligible.
Once vaccinated, you’ll have a much better chance at overall prevention of COVID-19. While the vaccines don’t prevent all symptoms of illness 100%, they do help reduce your risk of severe disease and hospitalization, and that’s no small feat. They also give you more options for safe social interactions.
In April 2021, the CDC released guidelines that when fully vaccinated, you can gather indoors with other fully vaccinated people without wearing a mask or remaining six feet apart—this, after more than a year of recommending that you only meet with people outside your household, donning a mask and remaining six feet away from your friends and loved ones. And, on May 13, 2021, the agency announced that fully vaxed people could resume their normal activities in most social settings, maskless, indoors and out. Also, once you’re fully vaccinated, you don’t have to quarantine if you’ve come into contact with someone who has tested positive for COVID-19, unless you show symptoms and/or you live in a group setting, like a correction facility or group home.
2. Maintain social-distancing. If you're not yet vaccinated or fully immune, you know the lingo: Stay six feet apart. The famous phrase has been repeated ad nauseum, and for valid reason: Because the virus can be asymptomatic in up to 40% of cases, people in close proximity can spread it without even knowing.
So when you’re out and about, around people outside of your immediate household (and you don’t know their health status or whether or not they’re vaxxed), it’s best to stay six feet away from them to err on the safe side. (And, remember, no vaccine is 100% effective at preventing all symptoms, so you still need to be cautious, at least for now.) The more people you’re around, the higher your chances of being exposed. When cases in your community are high (find out if yours is on sites like Kinsa HealthWeather), practicing good social-distancing is the smartest move.
3. Wear a mask. Everyone 2 years and older who is not yet fully vaccinated should wear one in public, according to the CDC, and masks are required on public transportation like trains and planes. Wearing one that fits tightly over your nose and mouth is key. And be sure to wash your hands before putting one on and taking it off, the CDC recommends.
In early April 2020, the CDC recommended that Americans wear cloth masks to help slow the spread of COVID-19. The announcement came after studies showed that people with the virus—but no symptoms—can still spread the disease, as we’ve mentioned. The CDC now recommends that if you wear a cloth mask, wear a disposable mask underneath and the cloth mask on top, or combine a cloth mask with a fitter or brace over it, to help enhance its fit. The goal is to have a snug mask that allows you to breathe easily but doesn’t have gaps between it and your face that might allow droplets through. One way to achieve that: Knot and tuck the ear loops of a 3-ply mask where they join the edge of the mask. The CDC offers a demonstration of this by video.
KN95 masks are a good option for fit and protection, but just know that about 60% KN95 masks are fake/counterfeit. The CDC is still asking that N95 respirators be reserved for health care workers.
However, if you are fully vaccinated—meaning, two weeks after the second dose of two-dose vaccines, and two weeks after a single-dose vaccine—the CDC announced on May 13, 2021, that you can return to your normal, pre-pandemic activities, just with a few caveats. “Fully vaccinated people can resume activities without wearing a mask or physically distancing, except where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance.” However, fully vaxxed people who also have compromised immune systems for any reason should speak to their doctor before ditching their masks, the CDC adds. For the "vaccine hesitant" crowd, and for all kids 11 and under, continuing to wear a face mask in all social settings is a proven way of protecting yourself and others.
4. Wash your hands. We know, we know—washing your hands used to be the main thing, and now it’s, like, fourth on this list. But good hand hygiene remains an important part of preventing the spread of this, or any, virus because we use our hands for just about everything we do. And we like to touch a lot of surfaces, which indirectly connects us to others.
So, wash your hands well before, during, and after handling food, eating, using the bathroom, blowing your nose, coughing … you get the idea. And there’s a right way to do it, too. First: Grab any bar or liquid/gel soap, either is fine. You don’t need an antibacterial soap, because this is a virus, not bacteria. (Actually, antibac soaps put us at risk for “superbugs”—bacteria that’s harder to fight off—so it might be better to avoid using them anyway.) Then: Rinse your hands with water, sans soap. To save on water waste, turn it off without touching the faucet (use a paper towel or your elbow if you can—if you can’t, leave the water running). Now: Lather soap all over your hands and between your fingers and under your nails. Do so for at least 20 seconds. Need some help counting those seconds? Sing the alphabet song A to Z, “Happy Birthday” twice, or parts of pop songs (like the chorus in Dolly Parton’s “Jolene” or Lizzo’s “Truth Hurts”). Finally: Turn the water back on, rinse the soap off your hands, and dry completely.
5. Use hand sanitizer. When you don’t have access to soap and water, use a nickel-size squirt of hand sanitizer with at least 60% alcohol, and rub it all over your hands until they’re dry (for at least 15 seconds). It’s not as effective as washing with soap—it kills bad agents with its high alcohol content but doesn’t slough it off your hands the way soap and water does—but if you’re in a pinch, or, say, riding on public transportation and can’t wash your hands right away, this is the stuff you want.
6. Avoid touching your face. Try not to touch your eyes, nose, and/or mouth with unwashed hands, as this gives germs easy access into your body. This area is called the “T” zone and studies show that we touch our T zones between 16 and 23 times an hour.
7. Stay home (if you can) when sick. Work from home remotely, if you can, when COVID-19 numbers are high in your area. But if you have to go to work or are an employee in an essential business like healthcare, drug stores, and grocery stores, it’s important to stay home when you’re sick, as a weakened immune system could make you more vulnerable to the virus. Talk with your employer about taking sick days, and ask a friend or family member to purchase necessities that can’t be delivered.
8. Skip the handshake (and the hug) if you’re unvaccinated. Or if you’re with people who aren’t vaccinated (or you’re unsure if they are), better to be safe than sorry on this account. Because close contact can put you at risk of infected droplets (especially if you aren’t masked/are wearing one that’s loose fitting). So, let people know ahead of time that you’re currently not shaking hands. Instead, offer a head nod, elbow bump, or the universally accepted air high-five.
9. Clean household items. Turns out, there’s still a place for cleaning/disinfecting, according to the CDC, just not the intense role they once played in COVID-19 prevention. Cleaning high touch surfaces daily with a household cleaner (like soap or detergent) is enough, the CDC says, to remove virus particles from surfaces. Think doorknobs, tables, countertops, your remote control, light switches, and so on. This includes electronics used often—your tablet, laptop keyboard, and cellphone (especially that cellphone).
Use a microfiber cloth and disinfectant to sanitize non-electronics. For electronic devices, unplug and turn off, then check the manufacturer instructions first to make sure a disinfectant-dampened cloth won’t damage anything.
So when should you disinfect? Use disinfectant like bleach when someone in your home is sick or if someone who is positive for COVID-19 has been in your home within the last 24 hours, the CDC now instructs.
10. Use supplements with caution. You may have heard about Chinese doctors using high levels of vitamin C to combat COVID-19 in hospitalized patients—more research is needed, but it’s not recommended to try this at home. In fact, it’s best not to take any supplements for virus prevention, as there is little research on possible negative effects.
If you do get COVID-19, zinc lozenges might (we stress “might”) help, as zinc has been shown to help shorten the duration of common cold symptoms.
How to Stay Safe From COVID-19 if You’re at High-Risk
If you’re still unvaccinated and over 60, or you’re a member of other at-risk groups for a severe reaction to the disease—folks with high blood pressure or diabetes, for examples, or who are immunocompromised or have a chronic lung condition—you might already know about prevention techniques. These include getting vaccinated ASAP, wearing a mask in social settings, and avoiding close contact with others because regular flu season poses a real risk to you already.
For you, dodging this disease (even after getting the jab) remains of paramount importance. Because some people are reporting symptoms that just don’t stop after the infection clears, living with COVID-19-related related months and months after having the virus. Called long-haulers, or those with long-term COVID, recovery has been challenging for tens of thousands of people. If you already have a chronic condition, potentially adding to it with symptoms of long-term COVID is clearly not advisable.
So, as vaccines allow more and more areas of the U.S. to open, as well as other parts of the world, it’s important to know your own risk/safety profile and adjust your behavior as necessary. Here’s what the CDC recommends doing for COVID-19 prevention if you’re high-risk:
1. Take everyday precautions. Keep at least six feet of space between yourself and others.
2. Avoid public contact. If you have to be in a shared space, wear a mask, keep away from anyone who is sick, limit close contact, and wash your hands as needed.
3. Avoid crowds. Stay away from big indoor crowds (think, 10 people or more) to limit your exposure to others.
4. Avoid non-essential travel. Now is not the time to fly to the Taj Mahal, for instance, according to the U.S. government, with the Biden administration restricting travel to hard-hit India in May 2021. Other areas, even those with lower viral caseloads, might not be the best option for you because getting there, if travel involves public transportation like an airplane, could increase your risk from exposure to crowds in enclosed spaces.
5. Stay home. If the COVID-19 risk level is extremely high/critical in your community, avoid going out to places like the grocery store or big box stores, especially on days when it might be crowded. Explore options like shopping at times that stores reserve for the elderly/high risk (often in the morning) when less people are in the aisles or having a shopping/home delivery service that many stores now offer.
6. Talk with your doctor. Knowing your risks can help you minimize them. Is there anything else you should, or can, be doing to stay safe?
7. Practice telemedicine. The FDA issued guidance during the pandemic to allow at-home monitoring of health measurements including blood pressure, body weight, and electrocardiography. Take advantage of this. Stay healthy, stay in communication with your doctor via the internet, and stay safe.
The advice here may help keep you safe from getting the virus. But no plan is foolproof. If you start feeling ill with COVID-19 signs or symptoms, call your doc and request a test. If it’s positive, know you’re not alone: You’ll be joining the ranks of the millions of people worldwide who’ve had the virus.
Once Vaxxed, Can I Travel? Shop? Work in an Office?
You might be wondering just what you can do to stay safe and prevent COVID. Being vaccinated is everything in this regard. As for travel for fully vaccinated individuals, you no longer need COVID testing before or after travel unless your destination requires it, and you don’t need to self-quarantine afterward, according to the CDC.
But individual states and countries have guidelines for visiting, as do airlines and other travel methods. It’s best to check in with your mode of transportation and destination before setting off.
For shopping and eating out, curbside pickup has become the name of the game. As has delivery, drop off, pick up, take-out, and other options for getting stuff. Those options may likely continue into the future, too, as companies discover new ways of social distance-level connecting with shoppers/clients/etc. Depending on the COVID-19 risk level in your area, your own risk factors, and if your house is fully vaccinated, shopping in-person might be a safe and fine thing to do.
As for returning to the office and working in-person (if you haven’t yet made this leap), the CDC says that employees will “will still need to follow guidance at your workplace,” so check in with your boss and see what’s going on in your industry. And again, always check in on your own risk/safety profile before gathering in any group of people who not your immediate family.
About COVID-19: The New England Journal of Medicine. (2020). “A Novel Coronavirus from Patients with Pneumonia in China, 2019.” nejm.org/doi/full/10.1056/NEJMoa2001017
How Do I Get the New Coronavirus: World Health Organization. (2020) “How Does COVID-19 Spread?” who.int/news-room/q-a-detail/q-a-coronaviruses
Social Distancing: Science. (2020). “Substantial Undocumented Infection Facilitates the Rapid Dissemination of novel coronavirus (SARS-CoV2).” science.sciencemag.org/content/early/2020/03/24/science.abb3221.long
How Long Contaminants Stay on Items: The New England Journal of Medicine. (2020). “Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1.” nejm.org/doi/10.1056/NEJMc2004973
Use of Zinc: The Journal of Family Practice. (2011). “Zinc for the Common Cold—Not If, But When.” ncbi.nlm.nih.gov/pmc/articles/PMC3273967/
Cleaning/Sanitizing: Centers for Disease Control and Prevention. (2020). “How to Clean and Disinfect.” cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/disinfecting-your-home.html
How to Protect Yourself if High-Risk: Centers for Disease Control and Prevention. (2020). “Protect Yourself.” cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html
Prevention Tips: Centers for Disease Control and Prevention. (2020). “Know the Facts About Coronavirus Disease 2019 (COVID-19) and Help Stop the Spread of Rumors.” cdc.gov/coronavirus/2019-ncov/about/share-facts.html
Chronic Diseases and COVID-19: JAMA. (2020). “Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China.” jamanetwork.com/journals/jama/fullarticle/2762130
Hygiene Theater: The Atlantic. (July 27, 2020.) “Hygiene Theater Is a Huge Waste of Time.” theatlantic.com/ideas/archive/2020/07/scourge-hygiene-theater/614599/
Current CDC Prevention Guidelines: Centers for Disease Control and Prevention. (March 8, 2021.) “How to Protect Yourself & Others.” cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html
All About Vaccines: Centers for Disease Control and Prevention. (April 23, 2021.) “Different COVID-19 Vaccines.” cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines.html
What Can You Do After Vaccination: Centers for Disease Control and Prevention. (April 27, 2021.) "When You’ve Been Fully Vaccinated.” How to Protect Yourself and Others. cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated.html
Types of Masks: Centers for Disease Control and Prevention. (April 19, 2021.) “Types of Masks.” cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/types-of-masks.html