COVID-19 Reinfection and Second Episodes of Olfactory and Gustatory Dysfunctions: Report of First Cases

The pandemic of coronavirus disease 2019 (COVID-19) is associated with a significant number of deaths worldwide. Currently, there is an increase of new cases of COVID-19 in Europe, leading to many hospitalizations of patients. ¹ According to the high rate of virus mutation, ² and the prevalence of patients without postinfection antibodies, ³ many questions rise about the risk of reinfection, especially in anosmic patients who may have less antibodies than nonanosmic individuals. ⁴ In this letter, we report 2 cases of patients who developed a second COVID-19, which was associated with a second episode of both loss of smell and taste.

A 42-year-old Parisian male developed moderate form of COVID-19 in March with dyspnea, fever, headache, diarrhea, and abdominal pain as main symptoms. The patient was home-managed and developed ageusia and total loss of smell at the end of the disease. Total loss of smell was characterized by a Sniffin’ Sticks test of 0/16 (Medisense). He had no nasal symptoms. Nasal swab was not performed because a shortage of tests (reverse transcription polymerase chain reaction [RT-PCR]) in France at this time. Serology testing was realized 2 months after the infection and reported mild level of anti-SARS-CoV-2 immunoglobulin G (IgG; 7.31). Patient benefited from 2-month olfactory training and reported that he progressively recovered smell (June). Gustatory function, defined as impairment of salty, sweet, bitter, and sour, recovered 1-month postinfection. In the end of July, patient had a normal olfactory function. In August, the patient traveled in a region characterized by a high rate of new cases of COVID-19 (isolated cluster region) and developed fever, nasal burning, and a new total loss of smell and taste. He had no additional symptoms. Patient was addressed in our Department in October 5, 2020. The clinical examination did not report edema in the olfactory clefts, and Sniffin’ Sticks tests (Medisense) revealed anosmia (7/16). A second serology using similar method that the first reported an increase of the level of anti-SARS-CoV-2 IgG (70.34), confirming the reinfection.

A 38-year-old Spanish health care worker developed a moderate form of COVID-19 in March 28, 2020, that was confirmed by 2 positive RT-PCR. She presented dyspnea, fever, headache, and diarrhea and was hospitalized for 7 days. She had no nasal symptoms. At the end of the hospitalization, she developed total loss of smell (Alcohol threshold test: 0) and ageusia. The 30-day RT-PCR postinfection was negative. The olfactory function recovered 6-week postinfection. At this time, the olfactory function was normal according to the normative data of ethyl alcohol threshold test. ⁵ In September 18, 2020, at the beginning of the second wave of COVID-19 in Spain, the patient was addressed to the department of otolaryngology for fever, headache, and new total loss of smell and taste. The RT-PCR was positive and a second alcohol test was realized, reporting total loss of smell (score = 0).

Loss of smell and taste senses are both prevalent in COVID-19 patients leading to impaired quality of life.^6-8 The recovery of gustatory and olfactory functions are still uncertain because 15% to 25% of patients have not yet recovery 3-month postinfection. ⁴ The possibility to be reinfected by COVID-19 was possible according to recent data, ⁹ especially in health care workers. ¹⁰ The serology may be useful to check the immunological pattern of patients or to suspect a reinfection in patients with increase of antibodies. In the same vein, reinfection may be diagnosed through repetitive RT-PCR but a particular attention should be paid for patients with long-term positive RT-PCR without COVID-19 infection. ¹¹ The rational to report the first cases of reinfection and redevelopment of olfactory and gustatory dysfunctions is strengthened by the need to inform both otolaryngologists and patients about the risk of not being sufficiently immunized, and to develop a second COVID-19. Irrespective to the clinical picture of patients, they have to respect recommendations (eg, hand washing, mask) to decrease the virus spread among the population. The anosmia may be managed by nasal lavages, oral corticosteroids, and olfactory training.^12,13 Future prospective immunological studies are needed to confirm our observations and to specify the rate of reinfection according to the initial COVID-19 clinical presentation and stages.