Despite early suggestions that the ommicron coronavirus subvariant BA.1 might be mild, a huge surge in infections in January caused spikes in hospitalizations and more excess deaths than previous variants. And the subsequent ommicron sub-variants don’t seem to be easing.
According to a preprint study using data from more than 1.5 million people in the UK, infection with the omicron subvariant BA.2 was more likely to be symptomatic, causing more symptoms and producing more symptoms. those people said affected their daily lives “a lot”, compared to an infection with BA.1.
In fact, BA.2 wasn’t just worse than BA.1; it was bad overall. The study authors analyzed symptom reports associated with infections of the ancestral coronavirus strain and variants alpha, delta, omicron BA.1, and omicron BA.2. The authors found that BA.2 infections were the most likely to cause symptoms compared to all other variants. And the finding held up when the authors adjusted for the time since a booster dose in people who had been vaccinated three times, suggesting that declining vaccine protection could not explain the increase in symptom reporting.
The findings are “contrary to the perception that recent variants have been successively milder,” said the authors of the study, led by epidemiologist Paul Elliott of Imperial College London.
Swabs and Investigations
The data comes from a large community survey called REal-time Assessment of Community Transmission -1 (REACT-1). The study sent questionnaires and swabs to people on the UK National Health Service’s patient register every four to six weeks from June 2020 to March 2022. Each round yielded between 95,000 and 175,000 viable smears, from which researchers could test for SARS-CoV-2 and use sequencing to differentiate between BA.1 and BA.2. (The other variants were determined based on the timing of dominance.) The questionnaire, meanwhile, asked people about 26 possible COVID-19 symptoms.
In all, the researchers had data from 1,542,510 adults, including 17,448 people who tested positive for SARS-CoV-2 and 10,709 who specifically tested positive for an omicron subvariant.
The percentage of people reporting at least one of the 26 COVID-19 symptoms was highest for BA.2, at about 76 percent. That’s compared to 70 percent for BA.1, 64 percent for delta, 55 percent for alpha and 45 percent for the ancestral strain.
Follow symptom
People infected with BA.2 also tended to report the highest number of symptoms, with an average of six symptoms in the week leading up to the positive test. That compares with an average of 4.6 symptoms for BA.1 and delta, 3.4 for alpha and 2.7 for the ancestral strain. And those symptoms tended to be more problematic. Compared to other variants, a higher proportion of people infected with BA.2 said their symptoms affected their ability to do “a lot” of daily activities. Nearly 18 percent of people infected with BA.2 said they were affected “a lot”, compared with 11 percent of people infected with BA.1 and 10.5 percent of people infected with delta (these data were not available from humans infected with alpha or the ancestral strain).
In a subgroup analysis of 4,800 people who had been triple vaccinated and infected with an omicron variant, the authors found that people with BA.2 were 64 percent more likely than BA.1-infected people to say that their symptoms interfered with their ability to express themselves. influenced to conduct. daily activities “a lot”. This analysis adjusted for time since the third dose as well as for other factors, such as age.
In general, the main symptoms of infection with the ancestral strain, alpha and delta, were mostly loss or alteration of taste and smell, but these symptoms were less associated with omicron infections. Instead, BA.1 and BA.2 symptoms were more likely to have cold and flu-like symptoms. Specifically, BA.2 was associated with chest pain, severe fatigue, runny nose, muscle aches, sneezing, fever, chills, fatigue, nasal congestion, and headache.
