As the Omicron variant swept Italy late last year, it was unvaccinated elderly people and those who had not had a booster dose four or more months after their initial shots who were most likely to go to hospital or die from COVID-19, according to data and doctors.
Cases in hospitals have started to plateau, offering a sign that the current wave - which started with the emergence of Omicron in late November and pushed infections to record highs - may be close to peaking, doctors say.
The data covering the period Nov. 19- Jan. 2 and published in recent weeks provide some of the most detailed insight into who was likely falling very ill from the newest coronavirus variant.
It also highlights the risks posed by the virus even as studies have shown Omicron causes milder illness compared with previous variants.
The rate of hospitalisation was 248.5 per 100,000 unvaccinated people in the period Dec. 3-Jan. 2, according to the most recent National Institute of Health (ISS) numbers published on Saturday.
The data did not say if the cases were Omicron.
That's up sharply from 172.4 in the Nov. 19-Dec. 19 period.
Within the unvaccinated group, people over 80 years old accounted for the vast majority of admissions, followed by 60-79 year olds.
A similar picture is played out in ICU and mortality records: people being admitted to intensive care totalled 31.3 per 100,000 people who had not been vaccinated, up from 23.1 in November.
Unvaccinated people accounted for 52.9 per 100,000 people who died from COVID in the period from Nov. 26-Dec. 26 compared with 42.4 per 100,000 from Nov. 19-Dec. 19.
Luca Lorini, an emergency room and intensive care head at Papa Giovanni XXIII Hospital in the northern city of Bergamo, has mainly treated unvaccinated people in recent months.
A smaller portion had received two doses of a vaccine but more than six months earlier and almost none had had a booster shot.
"At the moment all my patients in the ICU are unvaccinated," he told Reuters on Tuesday.
While Omicron is now the predominant variant in Italy and across the globe, there are still cases of Delta circulating. It accounted for almost 11% of cases worldwide, World Health Organization data this week showed.
Currently Lorini has 16 ICU patients with the Delta variant and 10 also with Delta recovering after a spell in the ICU.
He expects admissions to drop in a week or so as the infection rate has flattened out.
