What does it mean to 'boost' your immunity and can that help with the coronavirus?

Spend a bit of time online right now, and you can find everyone from unlicensed supplement promoters to naturopaths and even some physicians advertising immunity "boosts" to help protect against COVID-19.

Because there are no proven treatments or prevention measures for the novel coronavirus, many of these pills, injections and other services clearly cross a line into false advertising. Chiropractors, for example, have been forbidden from advertising any effect on immunity, and Health Canada has investigated more than 140 products that illegally claim to treat or prevent COVID-19.

Other times, it's a bit less black and white. Some businesses plainly state there's no evidence their products will help fight the novel coronavirus, but hint those same products could help build a strong immune defence against illness in general.

In an attempt to make sense of all this, CBC spoke with Bob Hancock, a microbiologist at the University of British Columbia who studies infectious diseases and the immune system.

"Immune boosting is not necessarily a bad thing, but it is absolutely not a way of protecting you against COVID-19 — full stop," Hancock said.

"You are not going to get better or protect yourself from the virus or really get any major benefit from the immune boosters to treat COVID-19."

Hancock explained some of the science in an interview last week.

What does it mean to 'boost' your immunity?

As Hancock explains it, the idea of boosting your immunity is a bit of a marketing ploy dreamed up by the "health food guys," but that doesn't mean there's no truth in it. He says there is a strong body of scientific evidence suggesting that some substances can help a bit.

"They serve to raise your level of immunity, but they don't really serve to prevent infections," Hancock says.

That's because these nutrients can play a role in what's known as the innate or non-specific immune system — the body's first line of defence against microscopic invaders.

It's a type of immunity humans share with everything from garden snails to house plants, and it includes physical barriers like the skin as well as defensive responses like mucous, bile and inflammation, all of which might help to limit the spread of pathogens through the body.

"That part of immunity doesn't work very well when people have nutritional deficiencies," Hancock said.

But innate immunity doesn't play a role in fighting off specific viruses and bacteria once they've taken hold.

What are some examples of potential immune boosters?

Vitamins, including A and C, and minerals like zinc and magnesium are often marketed for helping immunity, and according to Hancock, "in most of those cases there is a very, very good body of evidence that suggests that they're beneficial."

Hancock says he takes a multivitamin every day. He's also taken the herb echinacea in an attempt to prevent cold and flu, but acknowledges the evidence is a bit mixed.

"There actually was a controlled clinical trial on echinacea, and the first [trial] showed it worked and the second one showed it didn't work at all. So you can take whichever set of evidence you like," Hancock said.

"When you're dealing with these kinds of immune boosters, people don't work on evidence, they work on good stories."

He says anyone who's thinking about trying a product marketed as an immune booster should choose their sources of information carefully. He prefers physicians, "who are not perfect," but do know how to evaluate evidence, and scientific publications.

And if you're looking to get in a vitamin boost, Hancock says to forget the expensive injections and intravenous infusions, and opt for the supplement aisle at your local drug store.

Where do vaccines fit in?

An immune boosting vitamin is no replacement for a vaccine — they're not even in the same ballpark when it comes to preventing serious illness, says Hancock.

While so-called "boosters" might play a role in the innate immune system, vaccines work by stimulating the much more specific adaptive immune system, which is unique to vertebrate animals.

Vaccines normally work by injecting weakened or dead forms of a virus or bacterium, prompting the body to create antibodies.

"You will be defended against a future infection because the type of immunity you're raising is very, very specific — it's exquisitely specific for the particular agent you're worried about," Hancock said.

But as Hancock points out, most successful vaccines also contain immune-boosting elements called adjuvants — things like aluminum salts that help trigger a stronger response against the target, without actually providing any immune protection on their own.

"In a sense, this is the ultimate proof of this immune boosting concept, the fact that adjuvants exist and they work very well," Hancock said.