Digital contact tracing apps first emerged early in the pandemic. They’d let you know if you’d been around anyone who had tested positive, and they worked on a regular personal smartphone. So far, they haven’t been a silver bullet, and they’ve faced criticism over usability, privacy, and more. But they’re low-cost tools based on technology already in our pockets. Do they have a role now, as cases of covid-19 continue to spike, especially in the US?
I spoke about these issues with Rajeev Venkayya, who served as the White House’s biodefense advisor under George W. Bush and was responsible for that administration’s national strategy for pandemic preparedness. After that, he was the director of vaccine delivery at the Gates Foundation. He now heads the vaccine business of Takeda, a Japanese pharmaceutical company that is hoping to manufacture Novavax’s vaccine candidate.
This interview has been condensed and edited for clarity.
Q: Should we be telling people to use a contact tracing app at this point in the pandemic, when there’s a vaccine on the horizon? What is the utility of that technology?
A: First of all, we can take a step back and look at where we are in the pandemic. We’re in a very difficult place right now, with rising transmission cases, hospitalizations, deaths happening just about everywhere. In that context, contact tracing plays a different role than it will when you have relatively low levels of transmission. It’s going to be unlikely that you’ll get this back in the box with testing and tracing as your primary tool. It’s like bailing out a flooded boat.
Q: Does it make sense for a person to use an app in that context, then?
A: Absolutely … On an individual level, in fact, it’s more important now to download a contact tracing app than it was three months ago, because there’s a lot more virus circulating in the community than there was three months ago. If you’re going out to the grocery store today, even though everyone’s wearing masks, you’re being exposed to other people—and you’re more likely to pick up the virus today than you were three months ago. A contact tracing app will always help protect you as a person … from an individual standpoint, it’s always a good thing to know if you’ve been around somebody that has covid. That represents a threat to you and the people around you. And of course, you could become a threat to the rest of the community if you’re carrying covid and don’t realize it.
Q: Will those other ways of tackling the spread of covid-19 still be useful after a vaccine rolls out?
A: The vaccine news is incredible. It’s better than most people expected, to see such high levels of efficacy, and also to see that the first two vaccines are so effective in preventing severe disease. Having said that, it’s going to take some time for companies to supply enough vaccine to actually stop the pandemic. And in the US, at most, many people think that it’ll be the middle of next year before we see that happen. If there are manufacturing delays, which happens all the time in vaccines, then having all the tools that we can at our disposal—including robust testing and tracing—will be really important. You are just trying to keep up and to limit the damage that’s being done.
The vaccine in the early days is going to go to high-risk populations, which are going to be health-care workers and people in long-term-care facilities, and then maybe some critical-infrastructure workers. Those populations getting the vaccine is not going to be enough to stop transmission in the community. If you want to stop transmission in the community, you need to get to probably 50% of the population or more to really dampen the amount of virus that is circulating. So it’s going to be some time before we get there. Even if a vaccine is available, there are going to be people that want to wait some more time to see how things go with the vaccine before they’re going to be willing to take it.
Q: I have some questions about the way vaccines work. If you already have antibodies, does that impact how your body would react to the vaccine?
A: If you were exposed previously, it shouldn’t affect the potential of a vaccine to give you even better immunity than you received with a natural infection. The clinical trials that were done, most of them—that I’m aware of—did not exclude people that have previously had covid infections. And I don’t think we’d heard from anybody that we’re going to be withholding the vaccine from people that have previously had covid. There are a couple of reasons for that. One is that there’s a lot of variability in the antibody levels that we can measure after a person has had covid. And so you don’t know whether that level of antibodies, for that person, is going to be protective, unless you actually go in and measure that. And even then, we don’t yet have a clear-cut idea as to what level you need to have. And the second thing is that we know with other coronaviruses that you can have protection against reinfection for some period of time, but then that protection wears away or it goes down over time. And thirdly, we also know that in many instances, vaccines will provide more long-lasting protection than natural infection will.
Q: There are going to be several vaccines out there. Should a person take more than one?
A: In general, no, you should not be taking more than one vaccine against any pathogen or any virus. When these vaccines roll out, some of them require two doses. And you’ll want to take the second dose of the same vaccine that you took the first dose of. That’s not to say that it won’t be possible in the future to take a different vaccine as your second dose, but we need to collect data to understand whether you’re going to achieve similar levels of protection or better if you mix and match.
Q: If you’ve already been exposed, does that increase the risk of having an autoimmune reaction when you receive the vaccine?
A: We haven’t seen evidence of that yet. The concept is called disease enhancement. It’s this idea that if you’re exposed to a virus or potentially a vaccine once, and you get a less than complete immune response—like a partial immune response—the next time you get infected, and you’re actually exposed to a virus, you could have a more severe form of the disease for the reason that you mentioned: an immune system that’s overactive. That happens in dengue fever. It is a theoretical possibility with this vaccine. But all indications are that that’s not going to be a problem, based on what we’ve seen so far.
Q: Is there anything that you can see from your perspective in the vaccine rollout that we should have an eye on? Any bumps in the road that you’re predicting?
A: It’s going to be very complex. Every state is going to have its own system for doing this. So I do have an expectation that there’s going to be hiccups in the process. I think every state is hopefully doing the planning that it needs to do. But we’ve never done anything like this before, where you try to roll out so many vaccines to so many people in such a short period of time.
The other is that the cold-chain requirements for the mRNA vaccines are different from other vaccines. So we have to have freezers throughout the supply chain, as opposed to having just refrigerators, which is what people are more accustomed to. Then there’s the issue of making sure that people do take the second dose of the same vaccine, when they’re supposed to. And having a system that’s going to be reliable to make sure that happens will be very important. I do hope that states will have systems to make sure that whoever is in the priority group actually gets the vaccine as opposed to having the vaccine go to people that aren’t really supposed to be getting it early.
And then I think it’s going to be very important for everyone in the world to be monitoring for any side effects after people get the vaccine. We think that that’s unlikely to be an issue, but we need to watch for it just in case. Given how many people have received these vaccines so far, I doubt it would be something that would really change the way people think about vaccination. But we also want to maintain confidence in the vaccines. And so we need to be really transparent about these things.
Q: To that point about transparency and trust: Is there anything we’ve learned so far in this pandemic about building trust between health agencies and regular people who need to take action like download a contact tracing app or receive a vaccination?