Mild Covid-19 cases are likely to lose their sense of smell, study finds

For people with mild covid-19, the nose may know better than any other part of the body. New research released Wednesday suggests that nearly 90 percent of people have diabetes mild illness experience that they lose their sense of smell, a higher percentage than people with more serious illness. While usually temporary, this can cause loss of smell last six months and even lun.

The research, published in the Journal of Internal Medicine, looked at the medical records of more than 2,500 covid-19 patients who sought care in one of 18 hospitals across Europe. Most were outpatients with mild to moderate symptoms, while others were hospitalized with severe or critical covid-19.

All told, about three-quarters of the patients self-reported a loss of odor, known medically as anosmia. But there was a big gap in the presentation of this symptom across different levels of severity. In patients with mild disease, 86% reported loss of odor, compared with only 4.5% of moderate patients and 6.9% of severe patients. When looking only at patients whose odor loss was confirmed by objective testing, this gap narrowed but remained: Odor loss was confirmed in 54.7% of these milder cases, compared to 36.6% of the moderate to critical cases.

“Olfactory dysfunction is a common condition in covid-19 patients with a higher prevalence in patients with mild forms of the disease,” the authors wrote.

The findings are consistent with previous studies demonstrating that anosmia is a common symptom of covid-19 – although it was underreported in the earliest days of the pandemic. Other research has suggested that milder cases tend to have anosmia more often. But the new study is one of the largest of its kind to investigate its prevalence and to have data from patients with anosmia confirmed with tests.

Although this study cannot tell us why milder cases are more common prone to loss of their sense of smell, the authors have theories. The main explanation is that anosmia is ironically a sign that the body is properly fighting off the coronavirus. In these patients, the infection never spreads far beyond the upper respiratory tract due to a robust local immune response. But this reaction can lead to inflammation that damages or disrupts the nearby cells that help us process the smell, at least for a short time.

There can also be a false memory for more serious cases. Patients in the hospital often deal with many different symptoms, while the most critical patients require intensive interventions such as a feeding tube or artificial respiration. P.patients with a more serious covid-19 may not notice their anosmia while it is happening. That could explain the higher rates of anosmia in the study under moderateto-serious cases that were actually investigated for it.

Fortunately for most people who are experiencing covid-related anosmia, it seems to limit itself. The mean duration in patients was about three weeks, and about a third reported it lasted only two weeks. But 15% of the objectively studied patients lost their sense of smell for at least two months, while just under 5% still didn’t have it back by the sixth.month mark. Those with more severe anosmia at first they were more likely to continue to experience it months later.

The authors theorize that short-term cases of anosmia often represent nothing more than the stuffy nose and swelling often seen with everyday colds that can temporarily block our ability to sniff. But those with persistent anosmia probably have a more complicated problem on their hands, which means major damage to the olfactory cells, either through infection or inflammation. While most people who contract covid-19 can smell to their heart’s content afterward, the sheer size of the pandemic – with 86 million confirmed cases worldwide as of early January – means that many people could lose their sense of smell permanently.

The authors hope their research leads to future studies that will monitor these cases in the longer term to better understand the phenomenon and find out how someone’s chance of recovery.