A key part of studying a new virus is understanding the combination of symptoms presented in infected patients. Early on, scientists established cough, fever, shortness of breath, muscle pain, sore throat, and chills as symptoms associated with coronaviruses. Just recently, the CDC added a new symptom to the list: loss of smell.
CDC: COVID-19 Symptoms
"One gentleman said he realized it with hand sanitizer,” says Carol Yan, a rhinologist at the University of California, San Diego. “All of a sudden it was like water to him.”
Source: Knowable Magazine
This symptom signals to scientists that the virus is hurting more than just our respiratory system. In this article, we consider how the virus may affect neurological functioning.
Study 1: How common is the loss of smell in Coronavirus?
Three hospitals in Wuhan, China, provided the health information of 214 hospitalized patients with confirmed SARS-CoV-2 coronavirus infections. Patients were recruited from January 16 to February 19, 2020.
They analyzed neurological symptoms such as dizziness, headaches, seizures, impaired consciousness, taste impairment, smell impairment, and vision impairment.
In the sample, 88 patients had a severe infection and 126 patients had a nonsevere infection. Neurological symptoms were identified in 78 patients.
In patients with peripheral nervous system symptoms, 11 patients reported a smell impairment.
Source: Neurologic Manifestations of Hospitalized Patients With Coronavirus Disease 2019 in Wuhan, China
Interestingly, most neurological symptoms occurred early in the illness. On average, the symptoms were recorded within the first two days of illness.
Dizziness and headache were the most common neurological symptoms. Smell impairment was present, but the study does not tell us for sure that loss of smell is a symptom- at least, until a larger study came out.
Study 2: Confirmation from a larger study
An app, called COVID-19 Symptom Tracker, was released in March of this year. The purpose of the app was to collect data about hotspots, testing, and disease progression directly from the patients themselves. The app was released in the United States (US) and the United Kingdom (UK). After three weeks, over 2.5 million people reported their coronavirus-related health information.
In the UK, 64.76% of positive cases and 22.86% of negative cases reported a loss of smell and taste. In the US, 67.49% of positive cases and 17.33% of negative cases reported a loss of smell and taste.
The odds of losing your sense of smell and taste are more than six times higher if you have a confirmed case of COVID-19.
Source: Real-time tracking of self-reported symptoms to predict potential COVID-19
Why does this happen?
This coronavirus is not like your typical cold. Sneezing and running nose are not symptoms associated with coronavirus. The virus must be influencing your sense of smell in a different way than just blocking your nasal passages. Scientists think it’s all about the nerves.
Pay attention to your sense of smell
The loss of smell may be a milder symptom of coronavirus, but, nevertheless, it is a possible indicator of infection based on the early study and mass collection of patient data. We must pay close attention to the loss of smell and other neurological symptoms to avoid delays in care and further transmission of the virus.