The yet-to-be published research, from personal genomics and biotechnology company 23andMe, also found that nearly half of those with persistent post Covid-19 symptoms are experiencing complications for six months or longer.
While the research is yet to be peer-reviewed and is based only on patients self-reporting their long Covid symptoms, the findings are consistent with other smaller-scale studies which report that women are likelier to develop long Covid.
In the study, researchers surveyed data from more than 100,000 people who reported having Covid-19, of whom, about 25 per cent reported being long-haulers with symptoms such as fatigue and brain fog lasting for over 12 weeks.
The top symptoms reported by survey participants after they recovered from Covid-19 infection included brain fog, fatigue, and shortness of breath.
About 19 percent of them said they still had brain fog and about 14 percent reported having shortness of breath, a year after recovering from Covid-19 infection.
About 7 percent said they had heart palpitations, scientists added.
Of the 100,000 individuals, scientists say more than 26,000 reported that they had experienced long Covid, and over 7,000 said they’d been diagnosed with it.
Preliminary data from the ongoing study suggests women are at least twice as likely to be diagnosed with long Covid compared to men even when scientists controlled for age, ethnicity, and related health conditions.
Researchers found that people who self-reported that they had depression or anxiety prior to Covid-19 infection had a two-fold increase in the risk of being diagnosed with long Covid.
Individuals with heart-related conditions such as high blood pressure, coronary artery disease, type 2 diabetes, and high cholesterol were also found to have a 90 percent higher risk of being diagnosed.
23andMe scientists, including Catherine Weldon and Stella Aslibekyan say the findings are in contrast with other reports that men are much more likely to contract the novel coronavirus, and die due to the infection than women.
“More than 78 percent of those diagnosed with long Covid in the study were females, compared to about 62 percent among those who reported not having experienced long Covid,” researchers wrote in a blog post.
The findings also align with another research by scientists at the University of Milan in Italy which noted that women were more than three times as likely to develop long Covid than men.
Our overview of Post-Acute Infection Syndromes (PAISs) is out in @NatureMedicine. Given a substantial number of unknowns, this was a difficult topic to review. We have tried hard to be as objective as possible.
Huge thanks to @VirusesImmunity & @mhornig.https://t.co/buZiI2oiXz
— Jan Choutka (@jan_choutka) May 18, 2022
Scientists say long Covid could also be disturbing menstrual cycles with a quarter of the surveyed individuals reporting that they are still dealing with disruptions after a year.
People experiencing the most severe cases of Covid are also at a much higher risk of becoming long haulers of the condition, the study says.
“Individuals with Covid who required hospitalization had a more than ten-fold risk of being diagnosed with long Covid compared to those who were not hospitalized when controlling for age, sex, and ethnicity,” scientists noted.
While scientists did not find any genetic variants of the coronavirus associated with developing long Covid, they said the higher rate of cases in women may be due to differences in hormonal levels rooted in genetics.
Citing such examples of similar differences for other kinds of conditions, they said women are also much likelier than men to develop autoimmune conditions such as lupus or multiple sclerosis.
This hypothesis explaining the higher incidence of long Covid in women remains to be tested, but researchers say there’s already evidence that about a third of those diagnosed with long Covid had some sort of autoimmune disease, compared to only about 20 percent among those who reported not having experienced long Covid.
Citing the limitations of the study, scientists said the study relied on self-reported data from 23andMe consented research participants, adding that even diagnosis of the condition is still “nebulous and highly variable, and the reports can be subjective.”
“We include both information from those participants who reported that they were diagnosed with long Covid or simply reported that they had long Covid,” researchers added.
Scientists said the data and the findings are also not representative of the whole US population.
They called for further studies to continue documenting the natural history of long Covid over longer time periods.
Researchers warned that the public health impact of long Covid is likely to linger for years to come, adding that understanding the underlying biology and associations “may help as scientists wrestle with the best way to treat the condition.”