On Wednesday, the World Health Organization declared COVID-19 — the disease caused by the new coronavirus — a pandemic. Gov. Charlie Baker declared a state of emergency in Massachusetts Tuesday as the number of suspected and confirmed cases of the virus continues to climb. Dr. David Hooper, head of the infection control unit at Massachusetts General Hospital, spoke with Arun Rath, host of WGBH News' All Things Considered, Wednesday about what this means going forward. This transcript has been edited for clarity.

Arun Rath: So, we want to talk about the situation locally. But first, this announcement by the World Health Organization that this is now a pandemic. It's a sign of the spread of the disease. But in a statement, the World Health Organization also included some critical words about what it was talking about and an ineffective response in countries across the world. What are they talking about?

Dr. David Hooper: Well, it is a very challenging situation since we've learned that this virus does spread from person to person very efficiently. I think it has really required that countries step up and very actively institute social distancing type activities, as well as ramp up testing activities so that they could attempt to stay ahead of this virus. But that's becoming more and more difficult, as is apparent from the number of countries and the extent in these countries that the virus is being able to spread even within well-resourced countries such as the U.S..

Rath: And in terms of best practices for us right here, you mentioned, for instance, social distancing. Can you explain what that is and when it's appropriate?

Hooper: Well, for Boston, it's appropriate now. And it involves the use of appropriate hand hygiene after all contact with any other persons, probably avoiding handshakes and hugs, keeping your distance from other people in the three to six foot range, avoiding people who have symptomatic respiratory illness, avoiding touching your face after your hands might have inadvertently been contaminated from surface contamination of the virus. And of course, at a higher level, the cancellation of large gatherings to minimize the opportunity that large numbers of people will be together.

Rath: And what we're hearing there feels like basically every day about new cancellations of events for the situation here in Massachusetts right now. Can you give us a sense of of the scale? We hear of hundreds of people being quarantined. What does it actually mean in terms of the degree of isolation that people are going through?

Hooper: Depends on the state of quarantine. People who haven't been specifically diagnosed would have a compatible syndrome. They are supposed to stay home and limit their going out of their homes. Certainly anyone who's positive should very much limit their travel. And the guidance will come from public health is specifically what they should be asked to do or not to do. But it's avoiding if their known case, minimizing their contact with other people that could amplify the virus spread.

Rath: It seems that we're hearing a lot that that we should expect this to get worse before it gets better. Could you run through it for us here in Massachusetts right now, what are the things that people and families should be doing, if anything, to get ready for this, if it does get worse?

Hooper: Well, I think they, particularly the families with school age children, should prepare for how they would deal with school closings and handling child care under those circumstances. A number of companies have encouraged their employees where it's feasible for them to work from home to minimize coming in to work even in bad situations, as occurred in China.

People have generally been able to, at least periodically, with appropriate, again, social distancing activities to go out and go to the grocery store and the like. But there may be guidance in the future that you should only do that at perhaps lesser intervals than you were used to. So, stocking up on some food and water and supplies and obviously if you yourself become ill, then you should stay home. And if you become ill severely enough that you're concerned that you may need medical care, you should certainly call your primary care physician for guidance.