Winter is quickly approaching, when people will spend more time indoors and at crowded holiday gatherings. As the COVID-19 risk increases, just more than half of U.S. adults plan to get the latest vaccine, a new KFF COVID-19 Vaccine Monitor survey found.

One in five said they already have gotten the new vaccine that became available in September, with an additional 28% saying they definitely or probably will do so. The rest said they definitely or probably will not get the new shot. This large group includes 31% of all adults who previously got a COVID vaccine but now say they don't plan to get the updated version.

Among previously vaccinated adults who have not yet gotten the latest vaccine, half cite a lack of concern about getting the virus as a reason. Others said being too busy (37%), waiting to get it later (32%) or having had bad side effects after a previous dose (27%) are among the reasons why they haven't gotten the new shot.