Relying on herd immunity to COVID-19 could result in thousands of deaths: doctor

We've all heard lots about Saskatchewan reopening — so what will happen with plans to ramp up testing for COVID-19 and make sure the plan is working?

Dr. Alex Wong is an infectious diseases physician at Regina General Hospital

An undated electron microscope image made available by the U.S. National Institutes of Health in February 2020 shows the virus that causes COVID-19. (The Canadian Press/NIAID-RML via AP)

We've all heard lots about Saskatchewan reopening — so what will happen with plans to ramp up testing for COVID-19 and make sure the plan is working?

Infectious disease doctor Alex Wong was on The Morning Edition with Stefani Langenegger on Monday taking questions on that and more. 

Questions and answers have been edited for length and clarity.

Langenegger: We have had questions from people wondering about the safety of take-out. Do you have to go home and clean it off? What is the risk of transfer?

Wong: There's this whole transmission chain that has to occur all in sequence in order for someone to get infected from food or from a take-out container. I think it's notable that to the best of our knowledge, there's not been a single individual that's actually been infected [from] something like a take-out container or something that's actually related to food products or food services in any way shape or form in the entire world.

Basically what that means is it's exceedingly unlikely that you're going to get this from some some sort of inanimate object.

The real risk is when you're in close contact with individuals who are either asymptomatic or symptomatic. There's literally a respiratory droplet that needs to be freshly on that one little spot where you're going to touch on the cup with your lips. And the likelihood of that being the case is — I can't say zero, nobody can say zero — but it's infinitesimally low.

So in the end, if you choose to sanitize the cup before you before you drink your coffee, I don't think that's wrong. But when the absolute risk is essentially close to zero, you taking that additional step is basically not going to confer any meaningful benefit.

Can you comment on the idea that we shouldn't rely on herd immunity in terms of opening up the economy?

The short answer is that we need somewhere between probably 60 to 70 per cent of the population to actually be infected [and] recovered and that we presume that if you recover, that you have some degree of protection or full protection against the virus.

If all of our various interventions and social distancing and hand and respiratory hygiene measures actually work ... then we're hopefully going to be nowhere even close to that. Even in New York right now, when they've been doing antibody testing, they've only seen about 20 per cent of all New Yorkers [with immunity]. That's far, far short of the 60 to 70 per cent of individuals that you're going to need for herd immunity to meaningfully help to control this pandemic. 

I think for all of the developed world, in order to get to that 60 or 70 per cent number practically speaking, that's going to result in thousands or hundreds of thousands of people dying and that's not an acceptable thing. So I just don't think that's going to be in the cards for us.

I think it's going to be vaccine and the measures that we've been taking today.

One listener's elective hip replacement surgery was cancelled 10 days before the surgery date. They want to know: If elective surgeries are reinstated and they're one of the first to be offered an early date, how do they decide if it's safe to accept it?

The hospital setting throughout Saskatchewan generally is going to be very, very, very safe. We are not going to be in a situation where we're going to open things up for medical procedures and so forth without ensuring that safety is in order. 

There's definitely going to be a screening process that occurs probably the day before and the day that you present for your surgery in terms of ensuring that you're not symptomatic or that you've not had any contact with anyone either high-risk or confirmed to be positive.

Honestly right now the overall rates of community transmission are relatively low in Regina in Saskatoon specifically and through pretty much most of the province, with the exception obviously of La Loche up north.

The overall risk I think in the hospital setting is low and so I'm not entirely sure that you necessarily need to be too worried and to take too many additional precautions over and above the basic ones that we've talked about again and again.

You mentioned that one of the things you're interested in is testing and how that will be used as we begin to open things up. What will you be looking for in that regard?

Well for starters, I think there should probably be some public clarity in regards to what sort of capacity we have. I know behind the scenes lots of people have been working really hard to increase and to ensure the sustainability of our testing capacity and so that I'm not actually too concerned about.

I think the the the more interesting piece ... is how we're going to expand our screening processes to individuals who are may not actually be showing symptoms. So, high risk individuals who are close contacts of confirmed cases who may not actually show symptoms.

That's probably a potential high-yield group to be able to to to engage and to test. In other settings for example, if you've got a localized outbreak [like] up north or if you've got a situation in a nursing home or in another high risk setting like a homeless shelter or a long term care facility, then those are situations where you might want to consider mass testing including individuals who are asymptomatic as well.

with files from CBC Saskatchewan's The Morning Edition