Omicron infection: What are the symptoms?
Written by Maria Cohut, Ph.D. on January 10, 2022 — Fact checked by Harriet Pike, Ph.D.
As infections of the Omicron variant of SARS-CoV-2 — the virus that causes COVID-19 — continue to spread around the world, there have been reports that symptoms, in some respects, are different from those of Delta variant infections. Do symptoms really differ? What should you look out for?
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On November 26, 2021, the World Health Organization (WHO) indicated a new SARS-CoV-2 variant of concern, which became known as OmicronTrusted Source.
The variant has caused concern among health authorities because it appears to be highly transmissibleTrusted Source and likelier to reinfect.
There have also been some worries that Omicron can bypass the protection conferred by COVID-19 vaccines. Pfizer maintains that three doses of its mRNA vaccine are able to neutralize Omicron in laboratory experiments and that two doses may still prevent serious illness following infection with this variant.
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For these reasons, countries worldwide have been taking various measures and precautions to reduce the spread of Omicron among their populations.
Nevertheless, within a world in constant motion, it may be impossible to stop it from spreading altogether. Some cause for optimism may be that various reports suggest that infections with this variant tend to cause milder symptoms than those with previous SARS-CoV-2 variants, such as Delta.
But how can someone tell if they have the Omicron infection? Are the symptoms the same as those of infections with previous variants
What symptoms does Omicron cause?
The Centers for Disease Control and Prevention (CDC) lists the possible symptomsTrusted Source of a SARS-CoV-2 infection without specifying a variant. These are:
fever or chills
cough
shortness of breath or difficulty breathing
fatigue
muscle or body aches
headache
new loss of taste or smell
sore throat
congestion or runny nose
nausea or vomiting
diarrhea
Does it affect the lungs?
Medical News Today spoke to Dr. David M. Cutler, family physician at Saint John’s Physician Partners in Santa Monica, CA, to find out more about doctors’ advice regarding symptoms of an Omicron infection.
Dr. Cutler reiterated that symptoms vary and may not stand out in any particular way, compared to signs of infection with previous variants.
“The variety of symptoms seen with Omicron is the same as with other SARS-CoV-2 variants,” he said. “It seems quite notable that people affected by the same variant may experience quite different symptoms. Some get nasal stuffiness, others headache, sometimes body aches, and others get a sore throat.”
However, he noted, “[s]erious lung infections appear to be less likely with Omicron than [with] prior variants.”
That may be because, unlike other variants, Omicron preferentially infects the upper respiratory tract. This may also be why it seems to cause milder symptoms, according to WHO Incident Manager Abdi Mahamud.
“We are seeing more and more studies pointing out that Omicron is infecting the upper part of the body. Unlike the other ones, that could cause severe pneumonia,” he says, though cautions that more studies are necessary to confirm this.
How can you detect Omicron infections?
There have also been some anecdotal reports that lateral flow tests — also known as LFTs — may be less effective at detecting the presence of an Omicron infection.
Such tests, which people can do at home, are based on samples taken from a person’s nose, throat, or both and are meant to detect certain viral antigensTrusted Source, which indicate the presence of a viral infection.
According to Dr. Cutler, “[l]ateral flow tests are inherently inaccurate [because] [t]hey do not detect low levels of virus as well as PCR tests.”
RT-PCR tests, or PCR for short, are based on samples taken from both a person’s nose and throat. These samples, however, undergo laboratory testing, which can reveal whether SARS-CoV-2 specific genes are present. PCR tests are more sensitive and generally held as being more accurate.Will the vaccines work?
Vaccine manufacturers are cautiously optimistic. Oxford University, which developed a vaccine with AstraZeneca, has stated: “Despite the appearance of new variants over the past year, vaccines have continued to provide very high levels of protection against severe disease, and there is no evidence so far that Omicron is any different. However, we have the necessary tools and processes in place for rapid development of an updated COVID-19 vaccine if it should be necessary.”
Pfizer also sought to allay fears in a statement: “Pfizer and BioNTech are remaining vigilant and constantly conducting surveillance efforts focused on monitoring for emerging variants that potentially escape protection from our vaccine. We are beginning to run neutralization tests on the new Omicron variant of concern and expect to have initial data in the coming weeks.”
“In the event that a variant emerges that escapes protection of our vaccine, Pfizer and BioNTech expect to be able to develop and produce a tailor-made vaccine against that variant in approximately 100 days, subject to regulatory approval,” the Pfizer spokesperson added.
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