For the study, published on Wednesday in The BMJ, a team of Israeli scientists looked at the records of 1,913,234 patients from Maccabi Healthcare Services, a nationwide health care organization in Israel. Those patients were tested for COVID-19 from March 2020 to October 2021, before Omicron became the dominant variant of the virus.
To investigate long COVID in patients with mild infections, the researchers identified 299,870 patients who met the criteria. They then matched each patient with a person who tested negative for COVID-19 and had similar age, sex, time of test, and vaccination status, and followed the pair’s health conditions for a year.
When compared to their non-COVID counterparts, patients with mild COVID were found to have a significantly increased risk of conditions throughout the year of follow-up, including loss of smell and taste, breathing difficulties, weakness, palpitations, strep throat, dizziness, and concentration and memory impairment popularly dubbed “brain fog.”
For most of the patients, according to the findings, their long-COVID problems were resolved by the end of one year. Records also showed that children had fewer post-COVID symptoms than adults, and recovered from most of them in months.
In addition, the researchers found that vaccinated patients were less likely to develop breathing problems after breakthrough infections than those who didn’t get the vaccine, although the risk for other conditions was similar in both vaccinated and unvaccinated groups.
Maytal Bivas-Benita, a researcher at Israel’s KI Research Institute and the study’s co-author, told Agence France-Presse that she was “encouraged” by the findings, particularly after fears over long-lasting post-COVID symptoms.
“The vast majority of patients will be OK after a year,” Bivas-Benita said.
The researchers did note that their study has some limitations. For example, they relied on the electronic health record and had no access to those in free text format, so these data might not completely reflect diagnoses and outcomes reported. Another weakness is the potential underreporting of symptoms in the later periods, when patients failed to continue reporting their conditions after their COVID-19 diagnoses.
The U.S. Centers for Disease Control and Prevention maintains that long-COVID conditions can last for years.
“People with post-COVID conditions can have a wide range of symptoms that can last weeks, months, or even years after infection,” the agency says on its website. “Sometimes the symptoms can even go away or come back again.”