Question: How long after Thanksgiving will we know if there is a significant increase in cases that can be attributed to the holiday? We currently have tickets to fly across the country for Christmas but are waiting to see how things look before we decide whether we will travel. My son will be just nearly 10 months right before Christmas and he is our main concern, mostly being at the airport since that is where transmission risk is highest. We have nonstop flights so at least we don’t have to deal with multiple locations and our family we would like to visit are all fully vaccinated. It’s a very hard decision to make!

Answer: As you know, the Delta variant spreads quickly and easily.  It is more than 2x as contagious as previous variants and has a much shorter incubation period; the median time from exposure to positive test is ~4 days with the Delta variant as compared to 5-6 days with earlier variants (see Q&A of 7/13).  Given Delta’s speed, it would not take much time to know if there’s a significant increase in cases after Thanksgiving.  I’d say we would know within about a week.  

Making the causal connection to new cases and the holiday would, however, be challenging, especially since we still do not have strong contact tracing infrastructure across the country.  To start with, the decline in cases that the US was experiencing in Sept./Oct. 2021 has ended and the US is once again experiencing increases in daily cases, averaging >80,000 cases/day.  This time last year, the US was also experiencing increases in daily cases, which continued through Thanksgiving and into mid-January 2021.  The trend in new cases last year was unaffected by Thanksgiving; the US saw a 20% increase in cases in the weeks leading up to Thanksgiving and a 20% increase in cases in the weeks following the holiday.  But that trend line doesn’t mean that Thanksgiving holiday had no impact– it could have been that cases would have leveled off, but the holiday gatherings prevented that from occurring, although that’s just speculation.  If cases continue to increase throughout November and December, it will be hard to disentangle how much (if any) of the increase was due to holiday gatherings.  Regardless, your concern is about minimizing potential exposure to your baby during potential travel.  And in that respect, I think you’re right to be paying attention to levels of community transmission where you are and where you’re going.  And if you do choose to fly, be sure to minimize interactions and keep your distance from crowds as best as possible.  And once you’re on the plane, I suggest you choose a window seat for you and your son as it will be more isolated than an aisle seat.