Once again, it’s influenza season. The vaccine clinics are open, and the hysterical posts about the vaccine’s danger are appearing in social media. There’s familiarity to all of this, but also a big new change – at least in Canada, where I am. Pharmacists can now administer the vaccine. And it’s completely free to anyone in Ontario (where I am), so the barriers to obtaining the vaccine are pretty much eliminated. There’s no longer a need to drag your kids to their family doctor or line up at a public health clinic. Anyone can walk into a pharmacy, show their health card, and walk out minutes later, vaccinated.  It’s another enabling change that may help improve immunization rates, as uptake rates in the population remain modest.

This year’s flu season is (as of week 47) fairly quiet. Google Flu trends suggests a fairly typical picture, nothing like what we saw in 2009/10, the year of H1N1. My city’s influenza tracker reports only a dozen cases so far this season. Many of us will get our flu shot, continue with our lives, and not think about the flu until next season’s announcements. That’s the hope, anyway. Influenza can kill, and in its more virulent forms, is devastatingly deadly. The worst case scenario (so far) is almost unimaginable today. In 1918/19 an influenza pandemic killed 50 million people worldwide (5% of the population). So among public health professionals, that worry about the next wave is always present. Much has been written at this blog <plug>nicely compiled in the SBM ebook,</plug> on the efficacy and safety of the flu vaccine. In short, the vaccine is effective for both individual and population-level protection, but only modestly so, and its effectiveness varies based on its match with circulating strains. And despite widespread use for decades, there are frustrating limitations with the current vaccine beyond efficacy, including the need to repeat the shot annually. Someone said something about “going to battle with the army you have”. (I thought it was Crislip but he was quoting Rumsfeld.) The quote is apt. It’s not a perfect vaccine, but it does offer protection – if not directly to you, then indirectly to those at greater risk of infection. Hospitals and health facilities have been criticized for demanding health professionals either get the vaccine or wear a mask – and the arguments against vaccination are losing. But even the strongest advocates of influenza vaccine will acknowledge its limitations, which perhaps contributes to the understandable perception that there is more that could be done- beyond reasonable and effective precautions like handwashing and hygiene.

Whether it’s the confusion of colds with the flu, the known limitations of the vaccine, or the ubiquity of upper respiratory infections, there is no end to the products, therapies, and nostrums touted as influenza preventatives or treatments. And half of the population may be using them. In this realm, where evidence is mostly absent, pretty much anything goes. I was reminded of this by physician Yoni Freedhoff who noted that he was handed a coupon for “Flu Shield” after he and his family received the vaccine at his local pharmacy. These products are marketed like an extended warranty offer: Why stop at the vaccine? Buy the supplement for extra protection. At least extended warranties can occasionally be useful, unlike Flu Shield. Locally, the alternative-to-medicine purveyors are competing with public health endeavors by touting a monthly “homeopathic flu injection” while subtly discouraging the vaccine that actually provide immunization. Many of these products have been examined in detail in this blog, so I’ve compiled a list of the most actively promoted. I’ve categorized them loosely based on their plausibility and known efficacy data:

Possibly effective

Oseltamivir (Tamiflu): This is a drug, not a supplement, but worth mentioning as one of the few products that might work. There is published data to suggest oseltamivir is modestly effective for the prevention and treatment of influenza. However, given the lack of complete transparency with the oseltamivir clinical trials, it’s not possible to make any definitive conclusions about its effectiveness. Given any positive data would likely have been published already, my sense is that oseltamivir’s modest efficacy may be still overstated.

Unlikely to be effective

Vitamin D: While there’s evidence that some may be deficient in vitamin D, especially in the winter, supplementation doesn’t appear to have any effect at preventing infection.

Elderberry: There’s some promising data with elderberry suggesting it can reduce flu-like symptoms, but these findings it needs to be confirmed in larger trials. We’ve seen this pattern with just about every herbal remedy: Promising preliminary data, followed by less impressive data when better trials are done. It would be nice to see further studies to evaluate its effectiveness.

Zinc: Sold as lozenges for the treatment of colds, the effects are inconsistent. There’s no evidence showing efficacy for treating influenza. Zinc nasal sprays, such as Zicam, have been associated with permanent loss of the ability to smell.

Garlic: There is some preliminary data examining garlic’s effectiveness for preventing colds, but it’s inconsistent and the positive effects may not be real. There’s no evidence demonstrating any effectiveness of garlic for preventing or treating influenza. As preventatives go however, I’m supportive of any that also enhance my meals.

Ginseng: There are a number of forms of ginseng that have been studied for their immunostimulant effects. One of the more popular brands is Cold-fX. To the manufacturer’s credit, there have been some trials on Cold-fX examining its ability to help prevent colds and influenza. The data don’t suggest the effects, if any exist, are that meaningful. Whether it has any meaningful effects at influenza protection hasn’t been specifically studied.

Probably useless

Echinacea: Despite the hype and the marketing there is no persuasive evidence that Echinacea does anything to prevent or treat influenza. It’s one of the better-studied herbs for respiratory infections and is demonstrably ineffective. As Steven Novella noted, “The market for Echinacea endures, largely on a sea of anecdotes and marketing spin that is incongruous with the evidence.” If you think it works, you might feel better, but there’s no meaningful or measurable actual effects.

Wheatgrass: True modern-day snake oil, this is touted as an “immune booster” but isn’t any better than any other food.

Megavitamins: Sometimes called “orthomolecular” treatments, this is based on the idea that if vitamins in our diet are good, then massive doses of vitamin supplements must be better. The most commonly touted is vitamin c, but there’s no shortage of others. It’s the same idea behind the belief that vitamin infusions are a good idea. In the absence of a deficiency, there’s no convincing evidence that megavitamins have any beneficial effects for prevention or treatment.

Oil of Oregano: This is the herbal cure-all without demonstrable evidence of efficacy.

Definitively useless

Vicks Vaporub: Commonly used for symptom relief (it was around for the big pandemic of 1918/19), there’s no evidence it is effective for prevention or treatment. Even data showing it has any meaningful effects is poor. The active ingredient is camphor, a tissue irritant. There’s an urban myth that putting it on your feet will treat a cough, but that’s all it is – a myth.

Onion: Cutting up an onion and putting it beside your bed or around your house. Because onions suck up viruses, apparently.

Engystol, Pascoleucyn, and Gripp-Heel: These are homeopathic products. Like all other homeopathic preparations, there are no medicinal ingredients and are quite literally placebos, without demonstrable evidence of efficacy to prevent or treat influenza. Quite frighteningly, some that are approved as oral supplements (in Canada, at least) are marketed by the manufacturers (PDF) and administered by naturopaths as injections. Yes, they’re injecting oral products. Hopefully that water is sterile.

Oscillococcinum (Oscillio): The heart and liver of a Muscovy duck, fermented, then diluted to nothingness so the final product is 100% pure homeopathic placebo. Useless for both prevention and treatment.

Wet socks: This naturopathic strategy involves putting on a pair of cold, wet socks, covering them with dry socks, and then going to sleep. Apparently it will “‘rev up’ the immune system”, demonstrating the limits of the naturopathic understanding of immunity.

Pouring oil in your ear: Despite the claims, trying to heat a lymph node in your neck won’t have any impact your illness.

Despite all the limitations of the current flu vaccine, it still represents the most effective means of protecting yourself and the community from influenza. Despite the myriad of complementary and alternative remedies touted to prevent or treat influenza, there’s no convincing evidence for most treatments. This list isn’t exhaustive – if I’ve missed any popular ones, please let me know in the comments.


Posted by Scott Gavura