Diabetes part of the puzzle as to why Covid keeps going for some

The factors that make some people more likely to develop long Covid have been identified for the first time in a study.

The study tracked more than 200 patients for two to three months after their Covid-19 diagnosis. Picture: iStock

The factors that make some people more likely to develop long Covid have been identified for the first time in a study that links diabetes and auto-immune cells with a predisposition to developing the condition.

The research has found that the level of viral load initially in the infection was one factor that made a person more likely to go on to experience long Covid, together with the presence of autoantibodies. Other factors identified were the reactivation of the Epstein-Barr virus, which most people have contracted at some point in their lives and which lies dormant in the body, as well as having Type 2 diabetes.

The research has been published in the scientific journal Cell and involved dozens of researchers at several universities and centres, including the Institute for Systems Biology in the US, the University of Washington and Swedish Medical Centre in Seattle.

The study tracked more than 200 patients for two to three months after their Covid-19 diagnosis. Researchers analysed blood and nasal swabs when patients were diagnosed, during the acute phase of their infections and two to three months later.

They then surveyed the ­patients about 20 symptoms associated with long Covid, including fatigue, brain fog and shortness of breath, and corroborated those ­reports with electronic health records.

It was found that 37 per cent of the 209 participants in the study reported three or more symptoms of long Covid two to three months after infection.

A further 24 per cent reported one or two symptoms, and 39 per cent reported no symptoms. Of patients reporting three or more symptoms, 95 per cent had one or more of the four biological factors identified in the study when they were diagnosed with Covid-19.

Jason Goldman, the study’s lead medical author based at the Swedish Medical Centre, said the identification of the factors that made some people susceptible to long Covid might open the way for early treatment.

“Months after infection, all these vague symptoms are so hard to track down, because you’ve sort of lost that information, but if you look back when those symptoms are first triggered, it actually looks like it’s manageable,” he said.

One theory the scientists are proposing is patients with higher levels of autoantibodies after infection had lower levels of protective antibodies against the coronavirus. Lower protective antibody levels could lead to long-term symptoms because the body does not effectively clear the virus.

The US study comes after Australian researchers at the Kirby Institute and St Vincent’s Hospital for the first time identified immune molecules that remain ­active eight months after viral infection in long Covid sufferers.

The Australian research was the first study that had identified biomarkers in people with long Covid, biologically validating the little-understood condition.

It’s estimated long Covid ­affects between 10 and 20 per cent of people who were infected with SARS-CoV2, although vaccin­ation may reduce the incidence of the condition by 50 per cent.