..

Excerpts from:

https://www.caltech.edu/about/news/tip-iceberg-virologist-david-ho-bs-74-speaks-about-covid-19

As of March 20, more than 8,700 people worldwide had died of COVID-19, the disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Caltech trustee David Ho (BS ’74) of the Aaron Diamond AIDS Research Center, Columbia University, says that this is just the tip of the iceberg. Ho, an expert on viral epidemics, has spent decades researching HIV/AIDS, having begun his career in Los Angeles, “ground zero” of the first outbreak, in the early 1980s. On March 18, Ho sat down with members of the Caltech community to discuss the novel coronavirus and the future of our society in the light of this global pandemic.
–

Can you tell us about the pathology of the disease?

COVID-19 typically causes fever and a dry cough. One may have aches in the body—the muscles—and if it’s severe enough, there would be shortness of breath due to pneumonia.

Gastrointestinal symptoms can occur and are an indication of more severe disease. It’s not very common to have a runny nose or the sniffles, and a sore throat is not common either.

The incubation period from exposure to onset of symptoms is between four and six days; and if you want to cover 95–98 percent of the cases it is between three and 10 days. It’s pretty rare to have an incubation period outside of that range.

What in particular makes this virus so dangerous?

What is disturbing is that virus shedding, as detected in the mouth or nose, is very, very common and could be there prior to onset of symptoms. That’s why transmission could occur from asymptomatic individuals. And virus shedding could continue for days up to three weeks after a person recovers. That is extremely worrisome for the spread of this virus. Furthermore, the stability of this virus is worrisome as well. If you put it in aerosol form and keep it in the air, the half-life is several hours; if you drop it on surfaces of copper or cardboard, it could survive about a day. But if it’s on steel or plastic surfaces, you could still detect infectious virus after 72 hours, although the infectivity decreases with time.
–

Will this coronavirus be seasonal?

Everyone is asking whether this virus is here to stay. Initially, just based on what China did with SARS long ago, there was hope that warmer weather and more sunlight would help kill the virus in our environment and therefore lower the probability of transmission.

But now this virus has gained such a strong foothold in the human population. It’s already 25 times larger than SARS and it’s already embedded in the Southern hemisphere. If you look at Australia, South Africa, Argentina, Brazil, there are cases there already, and community transmission is occurring. As the weather changes, perhaps the Northern hemisphere will gain an advantage. But the epidemic in the Southern hemisphere is going to accelerate.

The long-term outcome may resemble influenza so that we have seasonal bouts, with the virus bouncing back and forth between the Northern and Southern hemispheres. This is of course just speculation, but that’s what we see with influenza.

Why does COVID-19 have less impact on children and more impact on the elderly?

Well, the latter part is easy. Older people generally do less well with all sorts of respiratory infections, including influenza and SARS. So that’s just the typical scenario we see. The children, however, are a mystery. As you know, children typically get flu or other respiratory viruses very quickly and bring them home to infect the parents. But in this particular case, the number of children infected in China, after extensive studies, don’t seem to indicate that this is the case for this coronavirus.
–

After a person recovers from the virus, how long are they still contagious?

That’s a very important question. We’re not sure; one individual in China was shown to have persistent virus shedding for over a month. But typically, we’re looking at a three-week period from onset of symptoms.

What should we be doing to limit the spread of this epidemic?

The social distancing and good hygiene strategies have been successfully applied, in South Korea for example, to bring their epidemic down. They’re the only other country that has flattened the curve—slowed down the number of new infections to not overwhelm the healthcare system—and gradually brought this epidemic under control. There are many places that have done a pretty good job of not allowing the epidemic to explode, such as Taiwan and Hong Kong. These are places that had quite a bit of experience in fighting SARS, 17 years ago.

Are you optimistic that these measures combined with research will be enough to combat the coronavirus?

I personally believe we will blunt this epidemic, but I think we wasted a good four to six weeks largely because of lack of testing and lack of a certain preparedness. But I think we could still make a difference and bring it under control with very harsh measures.

But again, are these measures sustainable? We’ve got to expect that businesses must reopen and schools must teach again. Whether it’s travel or sports or live entertainment, we’re going to have to return to some semblance of normalcy. But what are the measures that are effective and sustainable? That’s a question we as a society have to deal with. We need to buy time so that gradually the population will have a degree of immunity.

Most importantly, we need to buy time to allow science to deliver solutions. We’re going to have to develop drugs, antibodies, and vaccines. I think the mobilization by the scientific community, from my perspective, is amazing. So many people have mobilized and jumped on this and are contributing, from discovering small-molecule drugs that could block various enzymes of this virus to coming up with antibodies that could neutralize the virus. Researchers have already come up with a few promising chemicals that could be a good start to drug development. There are already a few neutralizing antibodies isolated from infected individuals; my own group is in the midst of doing all that.

And, of course, people are working on vaccines. A lot of companies are working on vaccines and those vaccines are at various stages. A couple are within weeks of entering human testing and that’s quite, quite remarkable. There is one thing about vaccines, though: Some of the experiments previously done on SARS suggested that when animals developed antibodies and then were given the virus, they had greater lung injury due to the presence of the antibodies. The scientific community would have to resolve that issue quickly and its resolution would either halt the current approaches or unleash them to move full speed ahead. We certainly will take a part in doing that. I think we have the real possibility that COVID-19 may become a fact of life until science comes through as it has done for past epidemics.

This is going to take some time. But I’m very confident that the science will rise to the task and provide a solution. But it’s not going to be a few months as our president suggests. It’s going to be much longer than that. I would say 18 months, or 24 months. I think we are all facing tough challenges ahead. Written by Lori Dajose

https://www.caltech.edu/about/news/tip-iceberg-virologist-david-ho-bs-74-speaks-about-covid-19

..

.