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'Delta Variant Has Literally Changed the Game,' Says Epidemic Tracking Expert

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AP Photo/Caleb Jones
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People line up to get COVID-19 vaccinations in Lihue, Hawaiʻi, Wednesday, March 3, 2021.

As Hawaiʻi watches the Delta variant spread locally and nationally, The Conversation spoke with Tim Brown, an expert in infectious disease modeling at the East-West Center.

Brown, a Senior Fellow in the Research Program, heads the center’s HIV modeling team. Like many working in HIV, Brown was drawn into efforts to respond to the pandemic, according to the East-West Center. His seminar on Thursday discussed the evolution of the Delta variant and future public health responses.

Below are excerpts from Brown's interview with The Conversation's Catherine Cruz, edited for length and clarity.

On how the Delta variant has affected the pandemic

BROWN: Fundamentally Delta has literally changed the game with this because it has increased its transmissibility so much. So in a lot of countries where previous levels of masking and social distancing were being effective, for example, in Taiwan or Thailand, we are now seeing major outbreaks of COVID, because of the Delta variant.

BROWN: We're seeing, of course, it's now 93% of infections in the United States, according to the Centers for Disease Control and Prevention today. So it really has changed the game and taken over the COVID market on a global scale.

On sending children back to in-person learning

BROWN: I would be concerned — if I had kids, I probably would not be sending them to school right now given that we are still seeing very rapid growth in the community spread here on Oʻahu. I'm sure you've seen the case numbers, we basically are now at 382 for the seven-day average, which is above our 250-peak from last July. So we are skyrocketing above where we were last July and there's no sign of slowdown, the trajectory is still very sharply up.

BROWN: I think it is more dangerous because this higher transmissibility cannot be underestimated. This is up at the level of transmissibility as chickenpox, which as we all know is extremely contagious. So imagine putting a group of children in school with chickenpox, without the vaccines would be the same as putting them in school with COVID right now. So I think we need to be very, very cautious on this. We need to remember that 135,000 of the 180,000 children in school here in Hawaiʻi are not vaccinated at this point. The vaccine is not available to those under age 12. And only about 60% of those aged 12 to 17 have received the vaccine here. So we're talking about a largely unvaccinated population in the schools. I would hope that all the instructors are vaccinated, although I don't think we can guarantee this at this point. And so there is serious potential there. I hope the governor is correct that these guidelines are strong enough for the schools. But honestly, if we start to see outbreaks in the schools by the end of this week, or in the next couple of weeks, we need to be very, very concerned and reevaluate where we are.

On his advice for staying protected from COVID-19

BROWN: My fundamental advice at this point is number one, if you're not vaccinated, you better get vaccinated and get vaccinated fast because it takes the vaccines time to take hold. After your initial shot, you need three weeks until you get the second one and then you need a full two weeks after the second shot before your full immunity is kicked in. And the other advice I have is: wear a mask whether you're vaccinated or unvaccinated. We are seeing increasing numbers of major outbreaks among vaccinated individuals. These are showing up in the media on a regular basis, but they were already being observed two to three months ago in healthcare workers in places like India, and many of those were super spreader events. So, we are very concerned that with this one, just vaccination alone may not prevent you from transmitting further.

Mask if you're indoors, absolutely. If you're outdoors, and far away from everybody — doesn't really matter if you have a mask on. But if you're within 6 feet of somebody, I would be masking. The viral loads associated with this variant are 1,000 times what they were with the previous wild-type variants with the original COVID virus. And what that means is that people who get infected with this, even if they are vaccinated, are much more infectious to other people.

One of the startling findings that CDC came up with last week, which was not startling to those of us who've been following this for some time, is that the level of virus in people who are vaccinated and people are unvaccinated with Delta is very similar for about the first week of infection. After that, the vaccinated people drop off very quickly once their secondary immune response kicks in and so they're probably less infectious after that. But in that first week, they are probably every bit as infectious as unvaccinated people. And that's something we really need to take into account when we're trying to deal with this. That means masking is mandatory. It's not an option anymore unless you are willing to contract the virus and then potentially take it home and spread it to other family members.

This interview aired on The Conversation on Aug. 5, 2021.

Catherine Cruz is the host of The Conversation. Originally from Guam, she spent more than 30 years at KITV, covering beats from government to education. Contact her at ccruz@hawaiipublicradio.org.
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