What's the latest on omicron for Massachusetts residents? One infectious disease specialist weighs in

Holiday get-togethers are just around the corner, while at the same time COVID-19 cases continue to rise. And, the omicron variant of SARS-CoV-2 has arrived here in Massachusetts, causing both concern and some uncertainty. GBH News reporter Mark Herz spoke with Dr. David Hamer, a professor of global health and medicine at the Boston University School of Public Health Medicine and an infectious disease specialist at Boston Medical Center, to catch up on the very latest on omicron and how the variant might impact upcoming holiday plans. The following transcript has been edited for clarity.

Mark Herz: Catch us up to the most current knowledge that there is right now on omicron.

Dr. David Hamer: Knowledge is evolving very rapidly for this variant of concern. I think some of the best data are coming out of South Africa and Botswana… they are seeing a rapid rise in cases in South Africa. And the rapidity of rise of new cases is faster than any of the previous waves that they've experienced. In addition to that, in parts of Europe, they're starting to see a surge.

There's a fair amount of initial epidemiologic data, that are not really strong, but they're suggesting that [omicron] is much more transmissible than delta was, which to me is worrisome because delta was much more transmissible than alpha.

So the virus is different — different enough that it's evading immune response. I think that there is evidence that a full primary series [of COVID vaccination], followed by a booster, leads to some degree of protection against omicron. And that's why many public health officials all the way up to [Dr.] Anthony Fauci are pushing for people to have boosters if they qualify.

The other aspect that we're learning about is severity of disease, and this is complicated because many of the cases or the patients that are getting this in southern Africa are having relatively mild disease. Some are being hospitalized, but their need for oxygen and more intensive care is much lower than in previous waves. And this may be because it's a milder strain of the virus, but it may also be simply that they have partial protective immunity from past episodes, and that's preventing them from becoming sicker.

So I think it's going to be important to continue to assess the virulence of this variant of concern over the next few weeks, when it starts to reach populations that have no natural immunity or vaccine associated immunity.

Herz: And the timing maybe couldn't be worse, because in the next two weeks a lot of people are planning on having get-togethers. And what does that mean? Is your advice changing or are your concerns changing?

Hamer I'm very concerned about holiday get-togethers, family gatherings and the like — I was concerned already before a few weeks ago because of the surge post-Thanksgiving. But if omicron is really moving in and starting to establish itself and it's this much more transmissible than delta has been, then we're at high risk and I think that people should be rethinking any sort of public gatherings they’re going to.

The state reported over 5,000 new cases [on Tuesday] and it's been running in the four to five thousand range over the last 10 days. But let's watch what happens over the next week. And if that rises further, I think people need to be really cautious and rethink any public gatherings they’re going to and any family gatherings, to add a level of caution to make sure everybody's been vaccinated and ideally boosted if eligible. And then even consider adding testing the day of a gathering with a rapid antigen test to try and reduce the potential risk of transmission.

Herz: When we look at Massachusetts breakthrough cases, in general, we haven't been concerned about the number of breakthroughs; because we should expect to see more and more breakthroughs because of the denominator here. The good news is that many people are vaccinated, as is my understanding. And the breakthroughs until now have been very mild, sometimes even asymptomatic. Are we still there at the moment?

Hamer: I think we're still in the same place… we have found pretty consistently since delta came to town, so to speak, that 70-80% of people are symptomatic, often with really mild symptoms, or runny nose, sore throat, a little nasal congestion — maybe a little bit more than that, with a low grade fever, fatigue, headache, a dry cough. But those resolved pretty quickly after three to five days.

So it's a relatively mild illness; but still, about three quarters of people are getting symptomatic infections. It's going to be interesting to see what happens if omicron becomes widespread. And what the relative proportion of symptomatic to asymptomatic is — in places where monitoring is going on. [But] if you're only doing symptomatic testing, then you're not [going] to understand what the relative proportion is.

This is going to be a rapidly evolving [situation]. So much has happened in the last seven days. Omicron is moving quickly.