Toronto Star Referrer

DR. PETER JUNI ANSWERS

QUESTIONS ON VARIANTS,

PATTY WINSA

We’ve heard the names — Alpha, Beta, Delta, Gamma — all variants of concern when it comes to COVID.

And just days ago, a new variant surfaced in South Africa — B.1.1.529, now called Omicron by the WHO — which is even more transmissible than Delta, which has already crushed its competitors and become dominant in Canada and the rest of the world.

Delta’s transmissibility led to cases doubling in a week in one area of Ontario after provincial restrictions were lifted.

Now cases are also rising in Toronto and there is reason to be concerned.

“In the presence of Delta, for those who are not fully vaccinated yet, there is no escape,” said Dr. Peter Juni, an epidemiologist and scientific director of the Ontario COVID-19 Science Advisory Table. One case of the variant leads to seven other infections in the unvaccinated on average, if no public health measures are taken.

“You either get immune through vaccination. That’s the easy way,” said Juni. “Or through infection. That’s the risky way.”

Juni says at least 95 per cent of the population would need to be vaccinated to reach herd immunity due to Delta’s “impressive” reproduction number pitted against vaccines that are 85 per cent protective.

There is no evidence yet to suggest that the newly discovered Omicron variant is in Canada.

What is known so far though, is that Omicron outcompeted Delta faster than Delta outcompeted Alpha, says Juni.

And the new variant probably has an edge on two fronts — it is more transmissible than Delta and evades the immune system more easily even in people who are vaccinated or who have contracted COVID.

On Friday, the federal government said foreigners who have been to seven countries in southern Africa — South Africa, Mozambique, Botswana, Zimbabwe, Lesotho, Eswatini, and Namibia — in the last 14 days would be banned from entering Canada.

And Canadian citizens and permanent residents, or others with a right to enter Canada, who have been to those countries would need to be tested on arrival and quarantine until they receive a negative test result.

We talk to Juni about breakthrough cases, waning immunity and how to protect each other during the holidays. The answers have been edited for clarity and length.

Do we know what is causing the current increase in COVID cases? Is it unvaccinated people, breakthrough cases, the transmissibility of the Delta variant or a combination of all three?

It’s a combination of all three. More than 85 per cent of the eligible population is fully vaccinated. Even though the vaccine reduces your risk roughly sixfold of getting infected, you will still see quite a lot of breakthrough cases in the vaccinated. It shouldn’t confuse people, breakthrough cases are absolutely normal. Currently, about half of infections come from the 85 per cent who are fully vaccinated and the other half come from the 15 per cent who are not vaccinated. If 100 per cent of the entire population were vaccinated, you would only see cases in the vaccinated. But this wouldn’t mean that the vaccine doesn’t work.

Unvaccinated people continue to be about six times more likely right now in the province to be infected. And they continue to be about 20 times more likely to end up in hospital and 25 times more likely to end up in ICU.

Why do breakthrough cases occur? Delta is very transmissible, and is partially evading the immune system because our vaccines introduce a spike protein through the mRNA sequence into the body that is still like the one on the wild type coronavirus. In addition, the current vaccines are intramuscular, therefore the type of antibodies we generate — IgG antibodies — act systemically, preventing hospitalization, ICU admission and death, but sometimes allowing the virus to enter the body and cause milder infections in breakthrough cases. If we had a nasal spray for vaccination we’d generate IgA antibodies, which protect the mucosa in the upper respiratory tract, and we might be better protected against infection. Nasal sprays for vaccination are being discussed right now so they’re still a couple years away.

Do we know how much our immunity is waning?

In Ontario, the extent of protection afforded by vaccines has decreased a little bit, from initially around 85 to 87 per cent to now about 80 to 82 per cent, according to our dashboard. But this is not just because of the (immunity) waning. Thanks to vaccine certificates, it is also because vaccinated people are now freer to expose themselves. They can go to restaurants and eat in a crowded dining room, whereas nonvaccinated people cannot. So, we think the breakthrough cases happening now may be due to a combination of exposure as well as a small decrease in immunity.

Why do we need a third dose?

The vaccines provide excellent protection against serious disease, but immunity will decrease a bit over time. Therefore, a third dose will start to be important first in older age groups and the most vulnerable people who are already eligible for the shot. And if we think about continued control of the pandemic, then also younger age groups will need to get a third shot. We don’t know yet where the sweet spot is, what kind of age cut off we want to use. But the shots will not only protect everybody better against hospital and ICU admission and death, but also provide neutralizing immunity against infection. That means you have antibody levels that are so high that even if the virus enters the body, it’s immediately caught and neutralized by the immune system’s IgG antibodies.

In the presence of this new Omicron variant, anyone who can get a third dose should get one immediately because every additional improvement of the immune response will be even more important for Omicron than for Delta.

Will the third dose stop breakthrough cases?

The third dose will do everything, including a reduction of breakthrough cases, as we can see from Israel, when it comes to Delta. (A fourth wave in Israel, which resulted last fall in a sharp rise of infections in those vaccinated, was brought under control by third doses and public health measures.) But keep in mind, Israel has had a three to four-week interval between first and second doses whereas we have had on average much longer intervals, which is to our advantage. Longer intervals between doses may mean that the immune system matures a bit more and that the immune response after the second does is more pronounced.

Why should we make Delta- or Omicron-specific vaccines when we have had so many variants? Is it because we can make mRNA vaccines quickly or because we think Delta or Omicron will be here for a long time?

I thought Delta would be around for a long time unless it will be taken over by another variant that has more mutations and makes it even more easily transmissible, which seemed quite difficult to achieve until two days ago. Basically, if you have a reproduction number of seven, like Delta, you’re pretty good as a virus. But now Omicron managed indeed to outcompete Delta — that’s evolution in real-time.

Now, we will need to see what kind of vaccines will be developed longer-term using the mRNA technology from Pfizer and Moderna to achieve better protection against Delta, against Omicron and against future versions of these two variants of concern with even more mutations. Right now, we will stick to the existing mRNA vaccines, which give excellent protection after two doses, and even more protection after three doses.

We are seeing cases rise since reopening. What do you think of these inconsistent masking policies, where we are required to wear masks shopping but not when we’re sitting

side by side in a jam-packed theatre watching a movie?

I think it’s a real problem. People use eating and drinking in nondining settings as a reason not to wear their masks. That’s fundamentally wrong. So what we would need to achieve as a basic is that the staff in the sports arenas, cinemas, et cetera, are doing the same thing as the flight attendants. Talking to people, say sorry, you only take down your mask quickly when you’re drinking or eating and then you need to put it back on. It could make quite a difference.

What would you say to people with the holidays coming? Should we be singing in church, shopping in crowded stores, having holiday parties indoors?

Look at Europe and look at the mess they’re having. When you see that, then you notice that with temperatures dropping, people moving inside, we all tend to be in more trouble than before. That’s one of the reasons we start to see cases go up. Transmission of this virus is airborne, therefore it loves if people are inside crowded spaces that aren’t so well ventilated. So, what is important is everybody should contribute to controlling this pandemic by just decreasing their contacts a bit. Ask yourself: Do I really need to go to all five dinner parties that I’ve been invited to? And do I really want to go into this crowded restaurant or could I just go somewhere else that is really well-ventilated and not as well-attended? And do I really need to see all my friends or can I restrict my circle of friends that I have close contact with to perhaps 10? But not 50 or 100. And singing in church is not really a good idea. Everything helps.

What about travel outside of Canada?

I think the risks associated with travel are not that different nationally and internationally, unless you are going to places that have considerably higher numbers than we do, which for Ontarians right now is basically the rest of the northern hemisphere.

We look extremely good compared with nearly everybody else in the world. Being fully vaccinated and having at least one negative PCR or rapid antigen test for people coming to Canada means a powerful reduction of the risk of introducing infections and new variants into the country.

The new Omicron variant, however, means that further requirements will be necessary for travellers from high-risk countries, which right now is South Africa and neighbouring countries and perhaps soon the entire continent. We may need to add additional tests, five or seven days after arrival, as well as quarantine requirements.

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2021-11-28T08:00:00.0000000Z

2021-11-28T08:00:00.0000000Z

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