Optimising Immunity to Protect against Coronaviruses

The outbreak of a new human form of coronavirus (Wuhan novel coronavirus, 2019-nCoV) in December 2019 in the city of Wuhan in China, is spreading fear and alarm around the world.

Around 56 million people in China have been under lockdown since Chinese New Year, and the Chinese government has just completed the fast-tracked building of the first of two new hospitals in Wuhan, to help cope with a rapidly growing number of cases. As at Monday 3rd February, 20,438 confirmed cases have been reported across all regions in China as human to human transmission occurs, and 425 people have died following infection with the virus, 414 of which were in Hubei province where Wuhan is located. Cases have now been reported in at least 25 other countries, though only one death outside of China has been reported to date.

As with other serious virus outbreaks that have emerged over the past 45 years such as Ebola virus, Bird Flu (H5N1) and Swine Flu (H1N1) virus, this coronavirus seems to have originated in another animal species (probably a bat), and jumped the barrier to be able to replicate itself in humans.

China is now more prepared than it was back in 2002 when the SARS (Sudden Acute Respiratory Syndrome) virus emerged, killing 774 of the 8090 people reportedly infected. Also, while it is relatively early days, indications are that the death rate from 2019-CoV will be less than that of SARS, at around 2-3% of diagnosed cases, versus around 10% for SARS. However, like all viruses 2019-nCoV is likely to continue to mutate rapidly, and new more pathogenic forms are possible.


The Coronavirus

Coronaviruses are a fairly large family of viruses that cause illness ranging from the common cold (responsible for 15-30% of cases), to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). They typically infect the respiratory tract, though the gut can also be affected.

Human to human transmission of 2019-nCoV seems to be relatively easy, though we are still learning about the various means through which this can occur. A 7-14-day incubation period seems to occur before symptoms begin to show, although even asymptomatic cases can be infectious,

Most 2019-nCoV patients initially hospitalised in Wuhan had fever at the onset of symptoms, and well as dyspnoea (shortness of breath) and a cough. Myalgia (muscle pain) or fatigue also seem to be common symptoms. The main cause of death is from pneumonia and acute respiratory distress syndrome(1).


Treatment Options

There are no proven effective antiviral drug treatments for coronavirus infections, and our biggest protection against this new virus or others that may come our way, relies largely upon the execution of good Public Health measures. Restricting travel, wearing masks, washing hands frequently, the use of sanitising agents and the isolation of those with suspected infections, is the best current approach to help reduce the risk of spread to others.

In considering the nature of the virus and what is known about it so far, there would appear to be a number of possible pharmacotherapy (drug and/or herbal) approaches, namely:

  1. Enhancing immunity to help protect against infection, or if it takes hold, to improve the body’s ability to fight it.
  2. Antiviral actions to specifically inhibit the ability of 2019-nCoV to take hold and replicate.
  3. Lung and respiratory tract protective, healing and anti-inflammatory agents.
  4. Other agents such as febrifuges and systemic anti-inflammatories, to help reduce acute symptoms in some cases.

Since this virus hit the headlines a plethora of articles and social media posts promoting a whole range of natural including herbal treatments has appeared, although the quality of many of these leaves much to be desired.

Just as drug developers have found it challenging to make drugs that have clinically significant antiviral actions, the evidence for herbal remedies having the same, is slim. I am not saying they don’t exist, because I’m sure they do.

However, claiming an antiviral action of a herbal preparation based upon an in vitro antiviral activity shown against a virus completely unrelated to 2019-nCoV, by an individual phytochemical found in relatively low amounts in a whole herb, and usually about which little if anything is known on its bioavailability (ability to be absorbed from the gut after oral administration and distributed to the area in the body where it needs to act), is a very far reach.

A more likely efficacious and evidence-based approach to incorporating plant-based products to help reduce the potential impact of this new virus on human health, is therefore to focus on enhancing immunity. Herbs that help foster greater immunity or that protect or help heal the respiratory tract from the acute inflammation, shortness of breath, pneumonia and respiratory failure that are main causes of serious illness and death, are worthy of consideration.


Optimising immunity

As with all infectious diseases, the level of pre-existing immunity to the microbial pathogen, is a key factor known to influence the susceptibility to and severity of an infection, and immunocompromised patients are more vulnerable to viral infections. The largest factor in immunity to influenza and coronaviruses seems to be serum antibodies induced by prior infection or vaccination, which impart a strong and disease specific host resistance to the virus. However, it will take many months or even years to develop a vaccine, and even then, the virus may mutate further by that time.

Plants have much to offer in terms of optimising immunity in humans, and a healthy vegetable and fruit rich diet, is increasingly linked with favourable influences on the gut microbiome and immune function(2). Many plant and mushroom derived preparations have been shown to help enhance human innate immunity (resistance) to different viral and bacterial pathogens, and a full review of these is not possible here. However, I consider Echinacea (Purple coneflower) one of the most promising from both a traditional as well as evidence-based perspective.



Echinacea was an important traditional medicinal herb to Native Americans, and different species were used to treat animal bites and a wide range of infectious and inflammatory conditions(3,4). Early European settlers to the Midwest adopted Echinacea purpurea and Echinacea angustifolia as a treatment for wounds and glandular inflammation, and it was a preferred treatment by many clinicians for infections until discovery of penicillin. There are now more than 1200 scientific papers published on it, and its principle application over the last 50 years has largely been as a prophylactic or treatment for colds and influenza.

Several clinical trials have shown beneficial effects of echinacea during the treatment of colds and influenza, although others have had less favourable outcomes. However, evaluation of these is complicated by the use of a diverse range of product types, plant part(s) and doses used.

Immune enhancement and modulation, and anti-inflammatory effects, are principal actions of echinacea, and numerous studies have reported immunological changes associated with echinacea root usage. Key outcomes seem to be increased numbers of circulating white blood cells, monocytes, neutrophils and natural killer (NK) cells, and the abilities of these immune cells to engulf and inactivate harmful microbes or carcinogens. This enhancement of the non-specific immune response, is thought to improve the body’s ability to maintain immunosurveillance against a variety of potential viral or bacterial pathogens or spontaneous-developing tumours.

Canadian researchers found that normal mice given Echinacea purpurea root had significantly prolonged life spans versus non-immunized mice(5). NK cells were also elevated in leukaemic mice receiving echinacea in their diet versus those who didn’t(6). Japanese researchers found Echinacea purpurea to have a suppressive effect on spontaneously occurring leukaemia caused by a murine leukaemia virus, an effect related to enhancement of immune systems(7).

Stress is known to reduce immunity, and echinacea has shown beneficial effects on stress-induced immunosuppression by increasing splenocyte proliferation and NK cell activity, while modulating blood levels of inflammatory cytokines(8).

Secondary or co-existing bacterial infections are also a common cause of pneumonia and death in patients with viral infections of the respiratory tract, and have been reported in approximately 10% of 2019-nCoV hospitalised patients(1). Viral infections can express bacterial adhesion receptors, and the virus-induced inflammatory response can also disturb the integrity of the physical barrier to bacteria. Evidence suggesting echinacea may prevent virus-induced bacterial adhesion to cell membranes, and moderate an excessive inflammatory response (cytokine storm) sometimes seen with pandemic forms of viruses(9,10), may therefore contribute to improved host resistance against pathogenic viral infections.

Alkylamides (alkamides), found in highest concentrations in the root, are now regarded as major bioavailable and active immunomodulatory components in oral forms of echinacea(11). However, microbes known as endophytes that live in close association with echinacea, also exhibit strong antibacterial effects against respiratory pathogenic bacteria such as Klebsiella pneumonia, Burkholderia cepacia and Acinetobacter baumannii(12-14). Recent research also suggests that inulin-type fructans found in echinacea, which are prebiotic compounds that promote a health microbiome, may also contribute to beneficial immunomodulatory effects(15).

In summary, while the situation in China and elsewhere will continue to evolve rapidly over the coming weeks, given its seriousness and the limitations of drug treatment options at this point, herbal options such as echinacea to help optimise our immune system’s resistance to 2019-nCoV or other viruses that will continue to come our way, should be considered.



  1. Huang C et al, Lancet 2020 Jan 24; epub ahead of print.
  2. Tomova A et al, Front Nutr. 2019 Apr 17;6:47.
  3. Felter HW. The Eclectic Materia Medica, Pharmacology and Therapeutics. Eclectic Medical Publications, Oregon, 1922.
  4. Smithsonian National Museum of Natural History, http://www.mnh.si.edu/lewisandclark/index.html?loc=/lewisandclark/home.html
  5. Brouseau M, Miller SC, Biogerontology. 2005;6(3):157-63.
  6. Currier NL, Miller SC, J Altern Complement Med. 2001;7(3):241-51.
  7. Hayashi I et al, Nihon Rinsho Meneki Gakkai Kaishi. 2001;24(1):10-20.
  8. Park S et al, J Med Food. 2018; 21(3):261-268.
  9. Rasmussen PL, Phytotherapy in an Influenza Pandemic: Swine Flu. Phytonews 32, 2009, June. Published by Phytomed Medicinal Herbs Ltd, Auckland, New Zealand. ISSN 1175-0251.
  10. Vimalanathan S et al, Virus Res. 2017; 2(233):51-59.
  11. Mudge E et al, J Agric Food Chem. 2011; 59(15):8086-94.
  12. Haron MH et al, Planta Med 2016; 82(14):1258-1265.
  13. Presta L et al, Res Microbiol 2017; 168(3):293-305.
  14. Chielleni C et al, Microbiol Res. 2017 Mar;196:34-43.
  15. Dobrange E et al, 2019 Oct 16;9(10). pii: E615.