As coronavirus cases explode across Massachusetts, the worst could be yet to come, according to Dr. Daniel Kuritzkes.

"I don't think that we're quite seeing the Thanksgiving surge yet," Kuritzkes, the chief of the infectious diseases division at Brigham and Women's Hospital, told GBH All Things Considered host Arun Rath.

Kuritzkes' comments come as Gov. Charlie Baker moves Massachusetts back a step in its reopening after some strong criticism. Below is a transcript of Kuritzkes and Rath's conversation about the rollback and other aspects of the pandemic. It has been edited for clarity.

Arun Rath: For much of the past week, the state's Department of Public Health has been reporting more than 4,000 new cases of coronavirus in Massachusetts each day. With this rollback to step one, phase three of the reopening - we're talking about limiting indoor capacity to 40 percent of restaurants and offices, places like that, capping outdoor gatherings at 50 rather than 100 people - is that enough to stem this wave that we're seeing right now?

Dr. Daniel Kuritzkes: I think we're really going to have to see what impact these new restrictions have. What's most important, really, is that people have to wear their masks consistently and reliably, and that is emphasized in the order from the governor.

Rath: The governor and others have been tying these skyrocketing case numbers to Thanksgiving gatherings and travel - maybe not so much travel across borders, but people going to households that are not their own. Do you agree that that that's been a big part of this?

Kuritzkes: I do think that there's good evidence that the majority of the cases we're seeing are the result of household transmissions, not so much transmissions outside the household.

Rath: We're facing the holidays. There's Haunkkah this week, and we have Christmas after that, Kwanzaa, after that the new year. If things are going up right now, thanks in part to Thanksgiving, there are just a lot more opportunities potentially for indoor gatherings in the next several weeks. How concerned are you about that?

Kuritzkes: I am concerned that the holiday season could further fuel the current surge that we're seeing. I don't think that we're quite seeing the Thanksgiving surge yet. It's just the very beginning of that, and so things really could snowball. I just think people are going to have to be very patient and willing to ride out this holiday season in the hopes that the holidays to come are going to be much more enjoyable than this year.

Rath: I want to talk over some of the vaccine news that we've also been getting lately. Honestly, I went into this past weekend feeling more optimistic, then a little bit less optimistic about things as more details came out. Probably the first thing to talk about is, it seems that there may not be in the first round as many doses coming to the states as we first thought.

Kuritzkes: Well, I think we always anticipated that there would be enough vaccine to dose thousands, tens of thousands of people, but not hundreds of thousands of people, in the in the initial weeks, with much more vaccine to become available in the following weeks.

Rath: One aspect I'm especially curious about with an infectious disease expert - we've been hearing about, in terms of the problem of distributing a vaccine during a pandemic, not just the logistical issues of it, but that if we don't have our infection rate down, even with the vaccine, we're still looking at a potentially very brutal winter and spring.

Kuritzkes: I think that's true. Even if we are able to get 30,000 people vaccinated in the next couple of weeks, that's a real drop in the bucket. We are still going to depend on people wearing masks, doing the physical distancing, limiting their gatherings indoors and the like for the foreseeable future until the majority of the population is vaccinated.

Rath: In terms of what will be available, how do you see that rollout going with where our numbers are right now? When do you think that we will start to see the effect of the vaccine?

Kuritzkes: The individuals who are vaccinated are going to be protected beginning about a month to five weeks after they themselves get the vaccine, but I don't think we're going to see an impact on the epidemic itself until well into the spring. I hope that before that, we'll see a reduction in cases because people will be following the advice from the governor's order and being more cautious about their activities.

Rath: As an infectious disease expert, obviously you can't you can't wave a wand, but what would be your ideal be for where the infection rate would be when we are able to start vaccinating people?

Kuritzkes: I'd like to see our positivity rate back down to one percent or less, the way we were over the summer. I don't think that's a necessary precondition for vaccination. It just means that without people taking the safeguards that are being recommended, vaccination alone is not going to do the job because it's going to take so much time to get everybody vaccinated.

Rath: The other aspect we've been talking about a lot in the last week has been about vaccine skepticism when it comes to that. Could you sort of refresh our memory on that? For the vaccine to be widely effective, how big a percentage of the population would need to have the vaccine by the time that we're finished with this?

Kuritzkes: So a quick back of the envelope calculation is that we need about two-thirds of the population to be immune to coronavirus to have so-called herd immunity. Since the vaccine is about 95 percent effective - both Pfizer and Moderna vaccines - then if 70 percent of people got vaccinated, 70 percent times 95 percent is about two-thirds, and that's the magic number. So we need at least 70 percent to accept the vaccine.