How have COVID-19 symptoms changed with different variants?

New research from Imperial College London's REACT study has shown how COVID-19 symptoms have changed with different variants.

The study, published in Nature Communications, describes symptoms from over 17,000 people who tested positive on a PCR test as part of the Real-Time Assessment of Community Transmission (REACT) study between May 2020 and March 2022.

The REACT study report includes data on more than 1.5 million randomly sampled adults in England across 15 of the 19 rounds. Each participant provided a swab sample and answered a survey which included questions on demographic variables, behaviour, and recent symptoms. The results show that symptom profiles among those testing positive have changed with different variants of COVID-19, and with changings levels of vaccination and natural immunity.

The proportion of people reporting any symptoms has increased with each variant. It was highest for Omicron BA.2, with 75.9% of those testing positive reporting at least one symptom. Whilst it was 70% with Omicron BA.1, 63.8% for the Delta variant, 54.7% with Alpha and 45% with the original wild-type.

Whilst there is a perception that each new variant has become successively milder the research showed that the Omicron BA.2 variant was associated with reporting more symptoms, with greater disruption to daily activities, than BA.1.

Those who tested positive with BA.2 reported an average of 6 symptoms in the week prior to their PCR test, compared to an average of 2.7 for the original wild-type (3.4 for Alpha, 4.6 for Delta and 4.6 for BA.1). Participants with the Omicron variants were less likely to experience a change in their senses of smell or taste than previous variants, instead reporting more cold- and flu-like symptoms (such as a fever, runny nose or cough).

Professor Paul Elliott, Director of the REACT programme, said: “Our study has shown that symptoms from COVID-19 have changed over two years of the pandemic as different variants of the virus have become dominant. This is against a background of changing immunity from prior infection and vaccination. Understanding these changing symptom profiles may help in identifying individuals who are at higher risk of transmission of the virus.”

The research team highlight that as routine testing becomes more limited in many countries and new variants continue to emerge it remains important to monitor both symptoms and the effects on daily activities.

Launched in April 2020, the REACT programme is one of the world’s largest and most comprehensive coronavirus monitoring studies. The programme is led by a world-class team of researchers at Imperial College London in partnership with Ipsos MORI, and commissioned by the Department of Health and Social Care.