Dr. Tom Hennessy is an infectious disease epidemiologist who’s been involved in Alaska’s response to the COVID-19 pandemic since March. He worked as an infectious disease researcher for the CDC for 25 years. Hennessy joined Health Chat host Martha Pearson on Nov. 18 to answer listener questions about the pandemic. This Q&A has been edited for clarity and brevity. You can watch the full “Ask a COVID Expert” event on our YouTube channel here.
Where did the coronavirus come from?
TH: This came from China. The first recognition we had of it was an outbreak that occurred in what they call a wet market, basically a big farmer’s market. The workers in the market there were getting sick, and they were spreading it to their customers and patrons. And that happened in the city of Wuhan. And that was the beginning of the outbreak back in January of last year. Perhaps there was some transmission in December.
They’ve looked at the genetic sequence of the virus that’s circulating in human populations and have compared it to some bat viruses that were isolated in China and found extremely high, close relationships with a bat coronavirus that was identified about two years ago in the same region. And this is what we know about these coronaviruses: they come to us from animals. So we know that they jump species, and they become able to transmit to humans through genetic mutation. Most of the emerging new infectious diseases come to us through the animal world.
How does it spread, and what does it do to make people sick?
TH: This is a respiratory virus that infects the upper respiratory tract and the lungs, and so people cough or sneeze or breathe it out in respiratory droplets that include mucus and basically, spit. So the virus gets into our respiratory tract, and it’s shed through there and gets in little droplets that we then either cough or sneeze or sing or yell or speak out.You’ve all seen those sneeze pictures where somebody sneezes, and there’s a cloud of yucky stuff that comes out. Those droplets vary in size from big ones that fall on your feet to little ones that begin to float in the air and travel across distances.
We know that from studies in outbreak situations that most of the transmission is in this six foot window with the immediate transmission of these droplets. Either they land on the person and then they get them in their eyes and nose and mouth and get into our respiratory tract. Or they might land on a surface that somebody touches and then they touch their mouth and then they get infected that way.
And that’s why so many of these measures are about wearing a mask to prevent you from spreading those droplets, so you don’t inhale those droplets. And keeping our distance and increasing ventilation so that if there are some that are floating around, that they get blown away. And so our mitigation measures are really based on what we’ve learned about the science of the transmission of these viruses.
Mask mandates specify that masks indoors need to be worn if six foot distancing can’t be maintained between people of different households. But we know that airborne transmission may also be important. Should mask recommendations say masks should always be worn in public indoors, regardless of distance?
TH: There’s been some really interesting studies that have been done in China and in Taiwan and in Hong Kong where they compared households that wore masks and those that didn’t when they had an infected person in them. And they showed in those settings that masks could reduce transmission from household contact by 70 percent. And we also have some other investigations that have been done, like on the USS Theodore Roosevelt — one of the naval warships where mask use was put into place. That also reduced transmission on that Navy ship with infected sailors by 70 percent. So there’s some good evidence mounting.
They’re not perfect, but they are sort of like going out in the winter. You know, you wouldn’t go out with just gloves on. You go out with gloves, boots and a jacket. So the masks are like the gloves, the distance is like the jacket and the boots. And so those things all together add up to a warmer winter coat and better protection for the individual.
I was a mask skeptic at first, I must say, because the evidence really wasn’t there. But I have come around from reading these studies and seeing what’s happened. We had a mask mandate in Anchorage that went into place. We saw a 15 percent reduction in the growth rate of COVID-19 in Anchorage in the two weeks after the mask mandate. And that’s without complete compliance and with a lot of people not wearing masks.
So I’m strongly in favor of mask mandates. I think they can make a difference. And I think people, if they want to protect themselves and protect others, they wear them all the time indoors when they’re around people that are not in their household bubble, whether they think they’re going to be within six feet or not, because you don’t know if you’re in the grocery store, you could turn around the corner and bump into somebody and you don’t want them coughing in your face and you don’t want to cough in their face, too. So it’s an added layer of protection.
How do I protect myself while traveling over the holidays?
TH: The safest thing to do is to not travel in an airplane over the holidays. To get in an airplane, you are taking a risk. There’s no doubt about it. Now, some airlines still leave the middle seat unoccupied, but you are in close contact with the people in front of you and behind you and one seat over. So you are immediately put in close contact with people and you don’t know anything about their COVID status.
Forty percent of people who get this infection don’t have symptoms, but can still spread it to other people. And it’s sort of mind blowing that you could have an infection, not be ill, but transmit it to other people. But we know this happens. It happens with influenza. It happens with a lot of other infections that we know a lot about. This is not brand new for COVID. And so that means any time you get on an airplane, you’re rolling the dice. And so I don’t think there is a safe way to travel on an airplane entirely.
I have had people ask how to do it. They put on a respirator mask, they put goggles on, they wash their hands and they just get on and hope and pray that they don’t sit next to somebody who’s infected. And then they get to their location and then they quarantine and they get tested. And it’s a big hassle. But if you’re going to visit grandma and grandpa and you show up with a coronavirus infection that you’ve got on the airplane and give it to them at Thanksgiving and you didn’t have to be there, I just don’t want to be in that situation.
We’re going to have to learn how to celebrate these holidays in a different way. And I miss my mother and father-in-law and I miss my sister and brother, but I’m just not going to be the person who travels to them and infects them and kills them. So that’s my take on it. Other people see that risk calculus differently, and I respect that. It’s going to be harder to travel until we get people vaccinated and immune.
If a person has recovered from the virus and completed their quarantine, do you recommend they behave any differently? Is it safe for them to travel, for example? Do they still have to wear a mask and maintain social distancing? Can they still infect others?
TH: This is a big question, and the answer is, we don’t know. We have 24 instances where there have been documented second infections. So to test that, they have to have a sample of the virus from the first infection that they save. So the person had a PCR test that was positive, they had an illness, they recovered. So that’s the first infection. And somewhere is saved a little sample of that virus. And then a month or more has to go by. And if that person gets infected again and develops a new infection with symptoms, there’s a PCR test that’s positive, and they save a little bit of that sample. The scientists will take those two samples, and they will compare them to make sure that the viruses are slightly different because it’s possible somebody could just have the same infection, it would be lingering, and then they would just have kind of a second outbreak of the illness. So we’ve had 24 instances published in the world where they met this standard.
And most of the time, this isn’t what’s done because we don’t save the samples. Nobody’s doing sequencing on them. We have thousands and thousands of other reports of people getting sick a second time, including my niece, who’s an emergency room physician in New York City and is taking care of thousands of COVID patients. She got sick in April despite wearing an N-95 respirator mask and goggles and all that. She’s just super careful. And then two months went by, and she got sick again. And she is one of the many thousands of people that we’re learning about that had clinical evidence of having a reinfection despite having gotten sick. And there’s thousands of these cases. They don’t have that high level of documentation with sequence matching and all those other things. But this is one of the things we’re going to learn as time goes on.
Why did my niece get sick from it a second time and why do other people not? Is it something about her antibody response or is it something different about the virus? How is this happening? And it’s one of the mysteries right now. But the short answer to this very important question is, yes, you can get COVID twice and sometimes the second infection is worse than the first one.
So if you had COVID and you recovered, you may be immune, but you should not act any differently than you did or should have the first time. You should still wear a mask. You should watch your distance. You should act as if you could get sick. And there have been some really, really tragic and unfortunate cases of people who got COVID once and got it again and either got sick or died or ended up in an intensive care unit. So unfortunately, we don’t know enough about the immune response. And what we’re hoping is that the vaccine is going to produce such great antibodies that we’re going to have long lasting infection protection from the virus.
Is there a link between how sick you get to the load of virus? So if you get a lot of virus all at once or if you just get a little bit of virus, does that seem to affect how sick you get?
TH: Yeah, it’s a great question, and it’s one that’s been asked a lot in the scientific community. There’s some good evidence that this does have an effect for other viruses. There’s been some really good studies in past influenza outbreaks, for example, that show that if you get a large dose of virus, you’re more likely to get sick and sicker.
I think the jury’s out on that still, and we’re gathering more information. But there have been some really interesting studies that show that people wearing masks tend not to get as sick. And I think those are really fascinating because that might be a reduction in the dose, but I don’t think it’s conclusive yet.
Has the vaccine trial been tested on adults with medical risks or just healthy adults?
TH: Both. So they didn’t exclude people with health conditions. In fact, they encouraged people of diverse ethnic backgrounds, older and younger people, people who had COVID. If they had underlying health conditions, that was OK because of the way they did it. They brought them into the vaccine trial and then they randomly assigned them to placebo or vaccine. And they wanted people that looked like the rest of the U.S. population.
Have you run a comparison of the psychological, emotional and economic costs, injuries and deaths caused by the disease versus the psychological, emotional and economic cost, injuries and deaths caused by the COVID measures?
TH: Wow. Well, that’s a really interesting and thoughtful question that really comes down to this harm reduction. And a lot of people have raised this question, I think legitimately. Are we doing more in our response to COVID that’s hurting people, hurting our economy, hurting people’s psychological well-being compared to the damage that the virus itself has done? And the kind of calculation that’s been asked in that question will not be able to be done for years because we don’t have ongoing immediate data about what psychological harm was caused by COVID versus the economic impact of government measures.
But what we do know is that we’ve had 250,000 Americans die and more coming. And those are people that would not have died if this virus had not visited us. And what we’re trying to do with all these measures that are restricting movement or encouraging people to distance is to prevent more illnesses and deaths. And one of the things that we’re trying to prevent is our healthcare system being overrun with COVID sick persons. We have to protect our health care workers so that they’re available, so that when you get in a car crash or you have a heart attack or your baby’s coming, you have health care workers who are there to take care of you. And so the way we do that is we limit the number of COVID infections by following these steps and saving our healthcare system. And we are in danger of potentially overrunning that.
It has already happened in the United States, in New York City. It’s already happened in Italy and Spain and in France. And that is the standard that I use is we have to control this to the point where we don’t overwhelm our health care system. Otherwise, the calculus that was described in that question will be overwhelmingly in favor of the virus. And we’ll have just so many people that will suffer as a result of that. So that’s my standard. Let’s not do any harm to people. Let us protect our health care system.
You know, most of the economic harm that’s come about in this pandemic is not a result of government action, nor the shutdowns we’ve had in Alaska. They’re actually relatively short lived. Most of the economic harm, the lack of tourism, was not because we told tourists to stay away, but because they stayed away, because they were fearful of the virus and coming and traveling. And people have stopped going to businesses because they didn’t feel safe. And until we get the virus controlled by vaccination and getting us immune, people are going to continue to be afraid rightfully. And our economy won’t recover. So control the virus first, then our economy can come back and people can start feeling safe again.
