Q&A: How Contagious Is the Covid-19 Delta Variant?

Q&A: How Contagious Is the Covid-19 Delta Variant?

After a spring when it looked like Covid-19 was in retreat, the highly contagious delta variant is surging in the United States. The delta variant is more infectious than previous variants and poses a high risk to people who are unvaccinated.

We spoke with Richard Novak, MD, head of infectious disease at UI Health, about the latest changes in the pandemic, shifting guidelines from the Centers for Disease Control and Prevention (CDC), and what it all means for our health.

What makes the delta variant more transmissible than the Covid we’ve known until now?

The delta variant has mutations in its binding sites (the part of the virus that binds to our cells to get in) that make it much stickier. It adheres with much greater strength to our receptors. It can grab on really effectively to our cells.

With the delta variant, people are shedding a lot of virus when they get infected, so they can spread it even though they don’t know that they have it. It can be spread asymptomatically, which didn’t seem to be true with the alpha variant.

Is it possible for vaccinated people to spread the delta variant?

Yes, vaccinated people can spread the delta variant. Recent studies show that they shed as much virus as somebody who’s not vaccinated. That doesn’t mean that the vaccine is not working. It is working — that’s why they have no symptoms.

Does the delta variant pose any extra risk to unvaccinated people who are considered high risk for Covid-19 complications?

Yes, the [variant] is much more contagious, so if they have not been vaccinated, the odds are that they are going to get this virus. Unvaccinated people are going to get it unless they’ve been living as hermits in a hole. That’s all the more reason to go out now and get a vaccine.

Why do the CDC’s mask recommendations keep changing?

This pandemic is constantly changing, and the CDC has to make adjustments based on such changes. They weren’t anticipating that the delta variant was going to arrive here with such force. Vaccinated people are not getting clinically very ill, but they are getting a lot of virus and can spread it, so it’s logical that we start wearing masks in indoor settings.

Does the delta variant spread outdoors?

Being outdoors offers more of a buffer, but there have been some outdoor settings where people were in close contact — dancing, standing right up against each other, like in Provincetown recently — and there was a lot of [Covid-19] transmission. Being outside is much better than indoors because of circulating air, but when people are in close quarters in huge crowds, the virus spreads — even outdoors.

What are your thoughts on the recent data from Pfizer showing that a third shot strongly boosts protection against the delta variant?

I’m really pleased [that it shows boosted protection]. I do believe there are going to be boosters, but I’m not sure when that’s going to happen. We’re involved in two-year Moderna and Johnson & Johnson trials, and a lot of the data that will tell us how long immunity will last is just beginning to come in now.

Elderly people and people with underlying illness may be approved to get a booster. It’s happening in other countries already. [But] the majority of the world has not had access to the vaccine yet. In Africa, where the pandemic is raging right now, only about 2% of the population has been vaccinated. These variants are coming from other parts of the world where the virus is replicating and will arrive here on our shores. It’s not enough for us to just vaccinate our own people.

What is your take on school reopenings?

The risk for getting outbreaks of Covid is really high in schools because a lot of the kids will be unvaccinated. That doesn’t mean schools shouldn’t open. Our kids need school. I would strongly encourage vaccine mandates for eligible kids, just as we do for other childhood illnesses that we have vaccines for. We should also mandate masks for students and teachers.

When might we have vaccines for children under 12?

That’s tough to say right now, but there should be study data soon. We know the vaccines are going to be effective in children, but are they going to be safe in children? That’s what the studies will tell us.

What brought about a drop in Covid-19 cases in India after its recent delta surge?

I don’t know for sure. It’s not just from vaccination, but probably because the virus is responding to public health measures — people wearing a mask and socially distancing. A lot of the susceptible people may have gotten it, and unfortunately many in India have died of it. Eventually [the infection rate] will go up until it peaks, and then it will start to come down. To get it to come down, we need an imposition of public health measures. We’re hoping [in the U.S.] there won’t be a huge bump, but if you look at the map, it’s happening where vaccine uptake has been poor.

At what point is Covid-19 considered more endemic than pandemic?

It will probably be getting to a point where we see seasonal outbreaks of it. There will always be some cases circulating at low levels. When we get to that point, the virus won’t be mutating as quickly because it won’t be replicating at such a high rate. There will be less opportunity for mutations to arise.

The big key is to get the rest of the world vaccinated because these variants are coming from other parts of the world. We can do what we want in this country to get the local epidemic controlled, but if a new variant arises in another part of the world, it will arrive in the U.S. and cause a new wave of infections. The delta variant came from India and the alpha from the U.K. We have our homegrown variants as well — none that have really taken off — but that potential also exists.

What’s your best tactic for helping people who choose not to get vaccinated understand the dangers of Covid-19?

I try to explain how viruses work and how they can spread it to friends and family. Some people say they’re going to wait [to get vaccinated] because the vaccine is too new. There have already been 165 million people [fully] vaccinated in the U.S. [as of early August]. How many more do you need to wait? We’ve known about the spike protein that the vaccine is made against for decades — since SARS, since 2003 when that outbreak occurred.

What are you doing in your own life to stay safe and keep others safe?

I’m not going to a lot of the events that I would like to go to, like concerts and things of that nature.  If we go to a restaurant, it’s mostly outdoors. I mask religiously when in public places indoors, like grocery shopping. I’m not as young as I once was, and I don’t want to get sick. [UI Health] is participating in a large study on long Covid. Some people get significant cognitive dysfunction after Covid. I just want to avoid it. I don’t want to find out what it’s like.