Enlarge / A longtime COVID patient sits with his daughter in his wheelchair while receiving a saline infusion at his home in Maryland on Friday, May 27, 2022.
Among adults vaccinated against COVID-19, the odds of developing long COVID in the middle of the omicron wave were 20 to 50 percent lower than during the delta period, with variability based on age and time. since vaccination.
The finding comes from an observational case-control study published this week in The Lancet by researchers at Kings College London. The study found that about 4.5 percent of omicron advance cases resulted in long COVID, while 10.8 percent of delta advance cases resulted in a condition of long term.
While the news may seem a little reassuring to those who are breastfeeding an innovative omicron infection, it is a cold convenience for public health in general, as the omicron coronavirus variant is much more transmissible than delta.
“Many more people became infected first with omicron than with delta,” Kevin McConway, professor emeritus of applied statistics at Open University, said in a statement. “Therefore, even if the percentage of infected people who had COVID during the two waves is on the scale that these researchers report, and may be, the actual number of people who report COVID for a long time after being infected for the first time during the omicron is even greater than during the delta “.
For The Lancet study, researchers looked at data from the self-reported symptoms of 56,003 adults in the UK who were first infected with SARS-CoV-2 during the omicron wave and 41,361 adults in the UK who were infected. initially infected during the delta period.
The researchers, led by Claire Steves, a senior clinical professor at King’s College London, defined COVID-19 long as having new or ongoing symptoms four weeks or more after the onset of acute COVID-19, which is how defines the U.S. National Institute for Health and Care Excellence Guidelines.
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When the researchers adjusted for age, time since vaccination, and other health-related factors, the relative odds of developing long-term COVID after omicron ranged from 23 to 50 percent. Chances were better when people were closer to vaccination (in less than three months) and were 60 or older.
Extended / Odds ratio of COVID (LC) long adjusted for age, sex, body mass index, multiple deprivation index, presence of comorbidities and vaccination status
The study has limitations, the most obvious of which is that it is based on self-reported symptom data and does not delve into the severity of long-term cases of COVID. There were also insufficient data to analyze long-term COVID rates among unvaccinated individuals, and the study did not include data on rates in children.
The study was also done during wave BA.1, as noted in a statement by David Strain, a senior clinical professor at the University of Exeter School of Medicine. Subsequent omicron subvariants, including BA.2, BA.2.12.1, and future BA.4 and BA.5, may have different profiles with respect to long-term risks of COVID.
However, even if the 4.5 percent estimate is maintained over time, this translates into many people developing long-term COVID. This “creates a significant public health burden of this disease without any known treatment, or even a reliable diagnostic test,” Strain added.
Steves echoed the sentiment, saying in a statement: “The omicron variant appears to be substantially less likely to cause long-term COVID-19 than previous variants, but still 1 in 23 people who catch COVID-19 have symptoms. for more than four weeks, the number of people affected, it is important that we continue to support them at work, at home and in the [National Health Service]. “