Protection from Viruses: Beyond Hand Washing
By Erica Zelfand

We share this wild planet with countless viruses, including rhinovirus (which causes the common cold), influenza A and B (which can lead to the flu), and COVID-19 (SARS-CoV-2), the latest coronavirus.

By now, we’ve all been reminded of the things we can do to limit our exposure to these infectious microbes – practices like social distancing, hand washing, and not touching our faces. While these strategies do, in fact, reduce our risks of catching respiratory viral infections and passing them on to others, many people will nevertheless catch viral infections. COVID-19, for example, has been shown to spread simply by breathing, and can be contagious for 14 days before the affected person shows symptoms of the illness.

Fortunately, the majority of people who contract respiratory infections survive. On another positive note, most viral infections have their “season,” and slowly wind down their presence as enough people go through it and build up antibodies.

Furthermore, there are things we can do to not only reduce our chances of getting sick, but also to improve our odds of getting over infections swiftly, completely, and without complications. It just takes a little education and preparation – and it all starts with healthy boundaries. (No, I’m not talking about boundaries in the Brené Brown sense – although those are important too! – but literal barriers, like the skin.)


Ode to Good Boundaries

The skin is the largest organ of the human body. Like the walls and gate of a castle, our skin protects us from all kinds of damage, keeping pathogenic agents (like toxins and microbes) outside and keeping water, blood, and nutrients inside.

The moist type of skin found under our eyelids, in our noses, and inside of our mouths is all called mucosa, or “mucus membranes.” In fact, if you look at the inside of your cheek in the mirror, you can easily observe a sample of the mucosa lining your digestive tract from mouth to rectum. Mucosa protects not only the digestive system, but also the respiratory passage and genitourinary tract.

While the skin and mucosa comprise protective barriers, they are more than lifeless walls. In fact, the sophisticated actions of the immune system are at play on these surfaces within and without us.

The skin and mucosa are more than lifeless walls. The sophisticated actions of the immune system are at play on these surfaces within and without us.

Defensins in particular play an important role in the protective function of our body’s barriers. Defensins are small peptides that, as the name implies, defend the body against bacteria, fungi, and viruses. By taking measures to increase defensins, we can enhance the body’s ability to kill upon contact any virus that lands on the skin.

Defensins are also found in mother’s milk, along with antibodies, so nursing mothers are encouraged to continue breastfeeding their children through cold/flu season. For the rest of us, the simplest way to increase defensins is by taking supplemental Vitamin D3.

In fact, multiple studies performed on patients in the intensive care unit (ICU) show a drop in all cause mortality in those with higher vitamin D levels.

Studies performed on patients in the intensive care unit (ICU) show a drop in all cause mortality in those with higher vitamin D levels.

One such ICU study concludes: “Deficiency of 25-hydroxyvitamin D before hospital admission is a significant predictor of short- and long-term all-cause patient mortality and blood culture positivity in a critically ill patient population.” In other words, hospitalized people who are low in vitamin D are more likely to die from all causes (including infections) than those with higher vitamin D levels.

For this reason, I typically recommend that my patients – from newborns to the elderly – take vitamin D3 on a regular basis.

Besides vitamin D3, other supplements for fortifying the body’s “borders” include vitamin A, zinc, glutathione, and probiotics. Vitamin C and elderberry are also immune-supporting, virus-fighting nutrients.  (I’ll talk more about these nutrients in a moment.)

Considering that viruses can more easily penetrate dry membranes, we can further protect our “barriers” by staying well hydrated. Simply put, this means drinking plenty of water. This also means applying paraben-free lotions to the skin, using hydrating eye drops (in those with dry eyes), and applying lip balm. Some people even like to put a little salve or natural lip balm to the end of a Q-tip and gently swab the openings of the nostrils, to keep the mucus membranes there protected. Running a humidifier in the home can also help keep the respiratory mucosa hydrated, and a high quality air purifier isn’t a bad idea, either.

While hand-sanitizing products kill microbes, this includes both the pathogenic (harmful) bugs as well as those that protect the skin. Alcohol-based products also tend to dry out the skin, thereby weakening its natural defenses. For this reason, I suggest using using hand sanitizer only as needed, and instead relying on hand washing with regular (not antibacterial) soap. Like commercial hand sanitizers, antibacterial soap dries out the hands and kills the protective, “good” bacteria on the skin. Antibacterial soap may lead to antibiotic-resistant bacterial mutations, or “superbugs.” Besides, as the name implies, antibacterial soaps kill bacteria, not viruses, making them somewhat superfluous in this season. A general rule of thumb is to use disinfectants on surfaces, not people.


Supplements for the Season

A basic mucosa-enhancing, immune-supporting protocol could entail any combination of the following nutrients. (Please see disclaimers at the bottom of this article before starting any new protocols.)

All of these are available through my online supplement store at 15% off retail price, at most health food stores, and at various other online shops. (Canadian customers, click here.)

Vitamin A

Vitamin A is also known as “the anti-infective vitamin” for its important role in supporting the immune system.

In a comparison of children who contracted the measles virus (another virulent virus), the children who were even slightly deficient in vitamin A were shown to be at higher risk of developing enduring respiratory complications and had higher mortality rates than those with adequate vitamin A intakes.

DOSAGE: Vitamin A (capsules, liquid, or emulsion): 25,000 international units (IU) with a meal daily. Double to 50,000 IU or higher if actively sick with a viral infection. Ladies, if you’re pregnant – or if there’s even a small chance you may be pregnant – keep the total supplemental dose of vitamin A well under 10,000 IU in pregnancy (check your prenatal and other vitamins for the amounts they contain, to make sure your combination of supplements stays under 10,000 IU total in vitamin A). The dosage in children is a bit more finicky. Kids 1-3 years: recommended daily allowance (RDA) is 1,000 IU, with maximum of 2,000 IU. 4-8 years of age: RDA 1,330 IU; max 2,000 IU. 9-13 years of age: RDA 2,000 IU; max 5,660 IU.

That being said, in the treatment of measles, a two-day protocol in children entails 50,000 IU/day x 2 days in babies under 6 months of age; 100,000 IU/day x 2 days in babies 6-11 months; and 200,000 IU/day x 2 days in those 1 year and up.

Vitamin D3

Vitamin D3 has been shown to protect against acute respiratory infections, including the common cold and influenza (flu) viruses. As explained above, it also increases the body’s production of skin defensins, which kill viruses upon contact.

DOSAGE: (capsules, liquid, or emulsion): Approximately 50,000 IU per week, all at once or in divided doses, preferably with some food containing fat (such as nut butter, avocado, olive oil, etc.). Double the dose for two weeks if infectious illness occurs. In children, guidelines for daily dosage is as follows: 400 to 1,000 IU for newborns and those under 20 pounds body weight (maximum dose: 5,000 IU/day); 20-39 pounds: 1,000 IU; 40-59 pounds: 2,000 IU; 60-79 points: 3,000 IU; 80-99 pounds: 4,000 IU; 100+ pounds: 5,000 IU.

[December 2021 Update: Since I first wrote this article, a huge body of scientific literature has come out showing that people with vitamin D deficiency are not only more likely to get COVID-19, but they’re also more likely to require ICU admission and are at higher risk of dying from the disease. Thankfully, supplementation can help! Check out my article on vitamin D to learn more.]


According to the World Health Organization (WHO), 13% of all lower respiratory tract infections, such as pneumonia and flu, in children age 5 and younger may be related to zinc deficiency, and a 2016 meta analysis found that zinc supplementation reduced the risk of pneumonia by 13% in this age group as well.

DOSAGE: 25-30mg twice daily with food. In children under 5, 15-25mg per day, and in those 5 and up 25-50mg per day is typically well tolerated. Give with food to prevent nausea.

Vitamin C

Vitamin C is an ace-in-the-hole immune support nutrient. High doses of IV vitamin C have even been used in China as a treatment of severe COVID-19 cases.

DOSAGE (any format, preferably low in added sugars):  1 gram (1,000mg) at least twice per day. During active illness, 1 gram every 1-2 waking hours may be safely taken by most. Reduce dosage if loose stools occur, or switch to a buffered vitamin C product. 500mg twice daily in children under 5 and 1 gram two to three times daily in kids 5 and up is typically considered safe.

Liposomal Glutathione

Liposomal Glutathione  is a powerful antioxidant especially important for protecting the lining of the lungs.

DOSAGE (capsules or liquid): Keep the bottle refrigerated, and take this one on an empty stomach, ideally. 250mg twice daily. If you have a nebulizer at home, compounded (non liposomal) glutathione can also be nebulized for direct respiratory support.

Multi-Strain Probiotics

Studies suggest that the routine use of probiotics can reduce the incidence of upper respiratory tract infections (URIs). Multi-strain formulations – such as Klaire Labs’ Ther-biotic Complete, Children’s Chewable, and Infant Formula – contain a mix of several different strains of Bifidobacteria, Lactobacilli, and sometimes other species as well.

DOSAGE: (capsules, liquid, or powder; tablets are my least favorite, but are ok too): 25 billion (not million) colony forming units (CFU) twice daily. Newborns and babies: 5 billion CFU daily. Keep the bottle refrigerated, unless it’s labeled as being shelf stable.


Elderberry has been shown to coat our cells, literally shielding them from viral attack. It also makes a tasty syrup that children and adults alike enjoy. (Just note that children under the age of 12 months should not take preparations containing honey.) And no, there is no substantial evidence that it will cause cytokine storm.

DOSAGE (various preparations): Take as directed. The general rule of thumb is that it’s pretty difficult to overdose on a food, and elderberries are food.


Staying Safe this Season

While the above recommendations may indeed enhance the body’s defense mechanisms, they’re not 100% guaranteed. It’s still important to take viral outbreaks seriously and exercise other measures to avoid exposure. While panic serves practically nobody, being blithe can likewise put us in harm’s way.

That being said, it’s good to have a little bit of safe, socially-distanced, immune-supportive fun every day. Did you know laughter is good medicine? It enhances immune system function through a variety of mechanisms!

So if you want to pretend you’re a defensin peptide on the surface of your skin and have a little dance party in your living room to M.C. Hammer’s You Can’t Touch This, go right on ahead. (But please, do take a video of yourself and post it to my FaceBook Page 🙂

Wishing everyone a healthy season and a series of slow, deep breaths, and lots and lots of defensins!




DISCLAIMER: Please note that many of the doses listed herein are higher than normal doses and likely should not be continued long term or outside of cold/flu season. These suggestions are typically safe for those with pre-established autoimmune disease. As always, check with your healthcare provider before starting any new supplements or changing dosages.

DISCLAIMER: I do not typically post specific dosages online, as it’s really best to talk with your healthcare provider to customize your care plan. Harm can be done from over-dosing some of these agents, even though they’re natural. That being said, during this time of pandemic crisis, I believe that in the name of harm reduction it is better to provide people with more information and trust each person to take responsibility for their own health choices and the choices they make on behalf of their children/families. Any changes you make to your healthcare plan are at your own risk; reading this article does not enter us into a doctor/patient relationship.

DISCLAIMER: Because COVID-19 is such a novel virus, we do not have much information or studies on what kills it or treats it best. The above are therefore general guidelines for upper respiratory infections shown to be effective with other viruses. None of these suggestions are guaranteed.



Special thanks to Heather Zwickey, PhD (AKA “The Zwickepedia”) for teaching me about defensins when I was in medical school, and for generally being the best immunology professor a doc could ever ask for.

Braun A, Chang D, Mahadevappa K, et al. Association of low serum 25-hydroxyvitamin D levels and mortality in the critically ill. Crit Care Med. 2011 Apr;39(4):671-7. doi: 10.1097/CCM.0b013e318206ccdf.

Pinheiro da Silva F, Machado MCC. Antimicrobial peptides: clinical relevance and therapeutic implications. Peptides. 2012;36(2):308-314. doi:10.1016/j.peptides.2012.05.014

Beard JA, Bearden A, Striker R. Vitamin D and the anti-viral state. J Clin Virol. 2011;50(3):194-200. doi:10.1016/j.jcv.2010.12.006

Green HN, Mellanby E. Vitamin A as an anti-infective agent. Br Med J. 1928;2(3537):691-6.

Martineau AR, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017 Feb 15;356:i6583.

Mora JR, et al. Vitamin effects on the immune system: vitamins A and D take centre stage. Nat Rev Immunol. 2008 Sep;8(9):685-98.

World Health Organization. Global health risks: mortality and burden of disease attributable to selected major risks. Geneva, Switzerland: World Health Organization; 2009.

Lassi ZS, et al. Zinc supplementation for the prevention of pneumonia in children aged 2 months to 59 months. Cochrane Database Syst Rev. 2016;12:Cd005978.

Carr AC, Maggini S. Vitamin C and immune function. Nutrients. 2017 Nov 3;9(11). pii: E1211.

Hao Q, et al. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev. 2015 Feb 3;(2):CD006895.

Field CJ, et al. Nutrients and their role in host resistance to infection. J Leukoc Biol. 2002;71(1):16-32.

Krawitz, Mraheil MA, Stein M, et al. Inhibitory activity of a standardized elderberry liquid extract against clinically-relevant humanrespiratory bacterial pathogens and influenza Aand B viruses. Complementary and Alternative Medicine. 2011;11:16.

Kern J, Geier D, Adams JB, et al. A clinical trial of glutathione supplementation in autism spectrum disorders Med Sci Monit. 2011; 17(12): CR677–CR682. doi: 10.12659/MSM.882125

Articles on laughter’s effects on health can be accessed here.

Article photo by Jaime Spaniol on Unsplash