LONDON: A new study has found that smokers are more likely to develop COVID-19 symptoms and end up in hospital, contradicting previous research that suggested smoking reduces the risks posed by the virus.

Researchers at King’s College London (KCL) analyzed data from more than 2 million people and found that smokers are more than twice as likely to end up in hospital from COVID-19, and 14 percent more likely to suffer from coughs, shortness of breath and fever.

They also found that smoking makes patients 50 percent more likely to develop multiple symptoms — including cough, fever, shortness of breath, loss of smell and appetite, fatigue, diarrhea and confusion — which experts believe is usually a sign of more severe infection.

The new study contradicts previous research that found smokers were less likely to catch the virus and suffered from less severe symptoms.

Those findings, which included studies from Mexico and data from Greece, had confounded researchers, contradicting conventional understanding of the negative impact of smoking on respiratory illnesses.

Dr. Mario Falchi, lead researcher and senior lecturer at KCL, said: “Some reports have suggested a protective effect of smoking on COVID-19 risk. However, studies in this area can easily be affected by biases in sampling, participation and response.”

He added: “Our results clearly show that smokers are at increased risk of suffering from a wider range of COVID-19 symptoms than non-smokers.”

Despite the early indications that smokers were at less risk from infection, the World Health Organization declared that smoking may make people more susceptible to COVID-19. The KCL research is the first concrete data to support this claim.

Claire Steves, lead researcher and consultant physician at KCL, said the findings could assist in the fight against the latest wave of COVID-19.

“It’s important to do all we can to reduce (the disease’s) effects and find ways to reduce hospital admissions,” she added.

“Our analysis shows that smoking increases a person’s likelihood to attend hospitals, so stopping smoking is one of the things we can do to reduce the health consequences of the disease.”