The coronavirus pandemic is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identified in an outbreak in the city of Wuhan in December 2019.
For over three years, the world has seen the coronavirus behind the COVID-19 pandemic evolve into many variants。Several variants have been named by WHO such as Alpha, Beta, Delta, Omicron, etc. They share the more infectious D614G mutation: Delta dominated, taking over earlier spreading variants. Omicron's immune escape ability may allow it to spread via breakthrough infections, which in turn may allow it to coexist with Delta.
Over time the top COVID-19 symptoms have changed as well.
Symptoms of COVID-19 are variable, ranging from mild symptoms to severe illness. Common symptoms include headache, loss of smell and taste, nasal congestion and runny nose, cough, muscle pain, sore throat, fever, diarrhea, and breathing difficulties. People with the same infection may have different symptoms, and their symptoms may change over time. Severe illness is more likely in elderly patients and those with certain underlying medical conditions.
Three common clusters of symptoms have been identified: one respiratory symptom cluster with cough, sputum, shortness of breath, and fever; a musculoskeletal symptom cluster with muscle and joint pain, headache, and fatigue; a cluster of digestive symptoms with abdominal pain, vomiting, and diarrhea. In people without prior ear, nose, and throat disorders, loss of taste combined with loss of smell is associated with COVID-19.
According to the most recent analysis, symptoms of infection with the prevailing omicron variant often resemble those of cold and flu.
Some coronavirus symptoms that were predominant with the delta variant, which preceded omicron, now rank way down on the list. These now less-common symptoms include loss of smell (among other sensory changes due to COVID-19, such as those that cause a metallic taste in the mouth). Shortness of breath and fever are no longer in the top 10 at all.
Top 10 COVID-19 Symptoms
These are the most common health effects indicated by contributors who tested positive for COVID-19.
- Sore throat
- Runny nose
- Blocked (stuffy) nose
- A cough without phlegm
- A cough with phlegm
- A hoarse voice
- Muscle aches and pains
- An altered sense of smell
Sneezing and a runny nose, previously thought to be unrelated to COVID-19, are now predominant symptoms. Sneezing is a key way that the virus spreads.
The reason for symptom changes is probably “multi-factorial,” and includes the virus’s ability to evolve in order to maximize transmission, and higher levels of immunity in the population due to vaccination and prior infection.
You May Think You Have a Cold or the Flu, Not COVID-19
Coronaviruses infect humans, other mammals, including livestock and companion animals, and avian species.
Human coronaviruses are capable of causing illnesses ranging from the common cold to more severe diseases such as Middle East respiratory syndrome. SARS-CoV-2 is the seventh known coronavirus to infect people, after 229E, NL63, OC43, HKU1, MERS-CoV, and the original SARS-CoV.
Because omicron symptoms tend to mimic those of cold or flu, people may not suspect they have COVID-19.
Infectious-disease specialists advise against the pandemic: Even mild, common, cold-like symptoms could be due to COVID-19, so people should be tested for the virus if they experience even mild respiratory symptoms, if they are vaccinated.
To avoid infection people should consider avoiding crowded indoor environments and wearing masks in such situations. These measures also provide protection against other germs, such as those that cause the flu and respiratory syncytial virus (RSV).
Vaccination, either flu vaccination or COVID-19 vaccination, may not provide complete protection from infection against some of the newer omicron sub-variants, but it will help protect against serious illness, hospitalization, and death.
On January 5, 2023, the World Health Organization's senior epidemiologist Maria Van Kerkhove said, XBB.1.5 is the most transmissible Omicron sub-variant that has been detected so far (January 5, 2023). It spreads rapidly because of the mutations it contains, allowing it to adhere to cells and replicate easily.
XBB and XBB.1.5 were estimated to account for 44.1% of COVID-19 cases in the United States in the week of Dec. 31, up from 25.9% in the previous week, according to data from the U.S. Centers for Disease Control and Prevention. It has also been detected in 28 other countries worldwide, the WHO said.
XBB.1.5 is yet another descendant of Omicron, the most contagious variant of the virus causing COVID-19 that is now globally dominant. It is an offshoot of XBB, first detected in October, which is itself a recombinant of two other Omicron sub-variants.