People who at first experience no symptoms when they have Covid-19 may still go on to become "long-haulers" – meaning they may develop and experience long-term symptoms later, according to early research, which has not yet been published in a peer-reviewed medical journal.
The pre-print paper, posted online to the medical server medrxiv.org last week, found that nearly a third of Covid-19 patients who were reporting symptoms more than 60 days after testing positive initially experienced no symptoms when first testing positive, making them asymptomatic.
"There has been conflicting information regarding whether asymptomatic individuals go on to become long-haulers, and roughly 32% of those reporting symptoms at day 61+ in our study were initially asymptomatic at the time of SARS-CoV-2 testing," researchers from various institutions in the United States wrote in the paper. SARS-CoV-2 is the name of the virus that causes Covid-19.
The new study included data from the electronic health records of 1,407 Covid-19 patients in California who were never hospitalized during their coronavirus infection.
More on the study: The researchers analyzed the Covid-19 symptoms patients reported during the first 10 days of their infection and then at least 61 days later, which was the criteria used to define "long-haulers." The researchers found that 27% of the patients reported symptoms at least 61 days later.
More women than men experienced lingering symptoms at least 61 days later, the researchers found, and the most prevalent symptoms were: chest pain, shortness of breath, anxiety, abdominal pain, cough, low back pain and fatigue. The researchers also found all age groups were represented among the "long-haulers."
The researchers noted in their paper that "these long-term consequences of becoming a long-hauler are unclear, and further research is urgently needed to corroborate our findings."