It might be possible to be infected with different variants of coronavirus at the same time, a preprint study from Brazil suggests. 

For the study, which has not yet been peer-reviewed, researchers from Feevale University in Brazil looked at the makeup of the SARS-CoV-2 virus, which causes Covid-19, in 92 people who had tested positive.

When researchers sequenced the virus – which is basically a way for them to track the virus’ mutations – they say they identified two people who had been infected with two different variants of the virus in November. 

One person tested positive for two separate Brazilian variants, the Daily Mail reported, while the second person was apparently infected by a Brazilian variant and another variant which originated in Sweden.

Their symptoms did not appear to be any worse than symptoms of those infected by just one variant, researchers said – and both patients have since recovered.

So, does this mean it’s definitely possible to catch two strains of Covid at the same time? The findings need to be taken with a pinch of salt for now because the study hasn’t yet been reviewed by other scientists. 

Some are sceptical of the study. One UK researcher, who wished to remain anonymous, told HuffPost UK he believed the samples had been contaminated in the laboratory, leading to duff results.

But Professor Lawrence Young, a virologist and expert in molecular oncology from Warwick Medical School, tells HuffPost UK he thinks it’s “perfectly possible” for that to happen. “It is not surprising, nor something to worry about, and has also been previously reported for SARS-CoV-2,” he says.

Spotting co-infection can be difficult, however. When a virus replicates at high levels in a person who is infected, errors in the copying mechanism of the virus genome can lead to mutations within the body itself.

“These can be detected by sequencing,” explains Prof Lawrence. “So when variants are detected, they could originate from an individual being co-infected with different viruses from another person or they could be generated within the infected individual.

“The way to discriminate is to compare variants in the population to those in the individual.”

Co-infection has been witnessed in other ailments over time too, such as flu.

Dr Julian Tang, honorary associate professor and clinical virologist at the University of Leicester, explains: “Co-infection of the same person with different viruses – even viruses from the same species (coronaviruses) but different lineages/variants – is not so uncommon amongst respiratory viruses.”

He says it’s possible, for example, for a child attending a primary school to get infected with one variant of Covid-19, and an older sibling to attend secondary school and get infected with a different variant, and for both children to bring their viruses home to infect each other and their parents with both variants.

Co-infections do not usually lead to more severe disease, says Dr Tang, adding that further studies are needed to monitor the frequency of such SARS-CoV-2 viral co-infections and the possible emergence of new mutations as a result of co-infections.