Most long COVID symptoms are resolved within a year of diagnosis, according to the results of a retrospective Israeli  study published last week in the peer-reviewed BMJ medical journal. 

“Our study suggests that mild COVID-19 patients are at risk for a small number of health outcomes and most of them are resolved within a year from diagnosis,” according to researchers.

The clinical definition of long COVID is still evolving. So far, it has been defined as persistent symptoms or appearance of new symptoms beyond four weeks from the diagnosis of COVID-19, which cannot be attributed to another condition.

More than two million people in the United Kingdom are living with long COVID, according to various studies published over the summer. Similarly, a report by the US Centers for Disease Control and Prevention showed in June that more than 40% of US adults have COVID-19 and one in five of those (19%) had long COVID symptoms. 

Long COVID symptoms can vary from loss of smell and taste, concentration and memory impairment and breathing difficulties to weakness, palpitations, streptococcal tonsillitis and dizziness.

The main objective of the Israeli study was to compare the long-term incidence of long COVID symptoms between uninfected people and people who were diagnosed with mild cases of the virus. To do so, the Israeli team analyzed electronic health records from the database of the country’s second-largest health fund, Maccabi Healthcare Services. 

Difficulty breathing

Some 299,885 members with complete data were eligible for the study, all of who had tested positive for COVID-19 between 1 March 2020 and 1 October 2021 but had not been hospitalized within 30 days of diagnosis. The eligible cohort was matched with 299,870 similar people who tested negative.

Potentially influential factors, such as alcohol intake, smoking status, socioeconomic level and a range of pre-existing chronic conditions were also taken into account.

Because of the study time period, the results covered all of the earliest COVID-19 waves, including the Delta wave, but did not include patients diagnosed with the Omicron variant. 

Over 70 long COVID conditions were analysed, comparing these during early (30-180 days) and late (180-360 days) time periods after infection. Conditions in vaccinated versus unvaccinated people with COVID-19 were also compared over the same time periods.

Chest pain, cough, hair loss, muscle and joint pain and respiratory disorders were significantly increased only during the early phase, the research showed. In contrast, brain fog, breathing problems, dizziness and weakness, heart palpitations, loss of smell and taste and strep throat remained risks in both the early and late time periods.

However, even for most of these symptoms, the risk difference between the people who tested positive for the virus and those who did not was less dramatic in the second six months of follow-up.

Difficulty with breathing was the most common complaint. The study found that vaccinated people were at lower risk of breathing difficulties compared with unvaccinated people.

In general, children had fewer long COVID symptoms than adults and recovered from most of them well within a year.

A separate study published by the UK Office of National Statistic in January found that around one-third (30%) of people who self-reported long COVID symptoms as of December 2022 reported experiencing symptoms for at least two years.

Nonetheless, “these findings suggest that, although the long COVID phenomenon has been feared and discussed since the beginning of the pandemic, the vast majority of mild disease cases do not suffer serious or chronic long-term illness,” the researchers said.

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