Despite COVID-19 case numbers reaching well into the thousands each day, the post-holiday season surge was not as bad as many expected, according to a new study from Northeastern, Harvard, Northwestern and Rutgers Universities. GBH Morning Edition host Joe Mathieu spoke with Northeastern University political science and computer science professor David Lazer about the numbers and his outlook for 2021. The transcript below has been edited for clarity.

Joe Mathieu: So what exactly happened over the holidays? Some people say it could have been worse and that the wave has crested; others say because of gathering over the holidays and the trends here with COVID — the new strain — that we are entering a dark winter that will see much worse conditions.

David Lazer: I think there's some truth to all of the above. I think that, to some extent, people did heed the calls to not gather for the holidays. We found in our survey 70 percent of people said that they essentially spent the holidays alone or just with people in their households. In Massachusetts, it was actually a little better still; around 75 percent said that they didn't gather with people from other households during the holiday. That's the good news, and we also have more good news, which is that people in the country have tightened up their social distancing behaviors since earlier in the fall and they are also wearing masks more. So that's all good news, and I think as a result of some of that, the fall and early winter wave was not as bad as it could be. However, there is bad news, which is that we have these new variants coming, and we do have a very hard few months ahead of us.

Mathieu: Before I ask you more about that, what do we know about demographics or any trends? Are there trends in those who chose to be responsible and those who chose to gather? Were there political lines drawn?

Lazer: Yes, unfortunately, we've seen a politicization of health behaviors really from early on. One of the biggest predictors of gathering for the holidays, as well as social distancing behaviors and mask wearing, has been partisanship. So Democrats wear masks more, they got together for the holidays less [and] they're social distancing more than Republicans. That's part of the reason why Massachusetts has done pretty well in all of these metrics is because it's a more democratic state. There are some other differences. For example, there are racial differences. So African-Americans and Hispanics are social distancing more and got together less for the holidays than white respondents. And there are big age differences. Younger people are behaving in a more risky fashion, perhaps because the age gradient of the risk of a disease. We put young people [at] a lot less risk than older people in terms of if they get sick.

Mathieu: There are crosscurrents. This new variant is a big deal, right, professor? Not in its level of deadliness or severity, but just spread. When we hear about Governor Baker rolling back some restrictions, does the timing worry you here?

Lazer: Absolutely. And what we know about the new variant, when we look at where it's become dominant in countries like the U.K. and Ireland, is that once it gets rolling, it just explodes. And so we know it's here, right? It's just that if it's starting from one case and then two cases and four cases and eight cases, it's still a rounding error. At this moment, we don't know exactly how common it is yet because, unfortunately, the U.S. has done a pretty lousy job of genomic surveillance, but at some point it goes from being at a very low level and it goes very quickly from being a low level to being a very high level. So it's very likely that sometime in the next six weeks or so, we're going to hit that crux in the elbow — the exponential curve — where it's just going to start going straight up and we're going to have to tighten restrictions up quite a lot then.

Mathieu: And that's February — about a month from now, you said?

Lazer: There's a lot of variation, so I wouldn't want to say, "well, it's going to be February 23," but the experts that I've listened to and talked to would suggest sometime in the next six weeks. We just can't really say is it going to be two weeks from now or six weeks from now, but that's a reasonable time range where we might expect it to start really exploding.

Mathieu: So what gives you hope here? Is it a mask mandate, as President Biden has begun to introduce, at least, in terms of airplanes, federal property and so forth, or are you holding out for maybe another vaccine — let's say J&J [Johnson & Johnson] shows up — or just more doses available so we can make more people eligible?

Lazer: Well, there are a few things that give me hope. We have a race now between vaccination and this new variant, and in the short run, the new variant of the coronavirus is going to win because we just can't go fast enough. However, as we vaccinate the highest risk populations, we will see death rates start to drop. So we have a hard few months ahead, but then we're going to hit a point where enough people will be vaccinated and other people will have gotten immune the hard way because they've been infected. Plus, there's clearly a seasonal element to the transmissibility. So as we move into the spring, we'll have the wind at our backs. Right now we're going into the wind and then once we get over this hump, we'll have the wind at our backs combined with higher levels of vaccination. So everything I see still leaves me a lot of hope that the spring will be a lot brighter than the winter. The winter is going to be dark, though.