(NEXSTAR) – Since the early days of the COVID pandemic, health officials have warned to watch for a number of symptoms, including the loss of smell. A study of those who tested positive for COVID shows that symptoms may not be felt if you become infected by the omicron variant.
Researchers reviewed symptoms from over 62,000 vaccinated participants from the U.K. who tested positive between June 1 and November 27 last year, when the delta variant was dominant, and from December 20 and January 17 when omicron was dominant.
While a loss of smell has been a common symptom among earlier COVID variants, the ZOE Covid Study – a joint effort with researchers from Massachusetts General Hospital, the Harvard T.H. Chan School of Public Health, King’s College London, Stanford University School of Medicine and the health app ZOE – found fewer than 20% of participants reported the symptom after omicron became dominant. If it was reported, it didn’t occur until days after other symptoms had appeared.
This isn’t much of a surprise – earlier this year, a handful of smaller studies found the loss of taste or smell was less common with the omicron variant than with others. The latest research from ZOE found other symptoms also seem to be fading with the omicron variant.
“Many other more serious symptoms — like brain fog, eye soreness, fever, and headaches — were all significantly less prevalent in omicron cases, though they can still occur,” an update to the ZOE Covid Study reads. A sore throat and hoarse voice were “consistently more prevalent” among participants with omicron than those with delta.
Overall, researchers said omicron symptoms also do not last as long among those who are vaccinated, and participants were less likely to be hospitalized with the dominant variant than those with delta. This is likely due to omicron being more inefficient at infecting lung cells – which can cause more severe symptoms – than delta, but more research is needed to support this, the ZOE update notes.
ZOE’s study doesn’t include findings on subvariants that have appeared since January, but some doctors say anecdotally that they’re seeing more reports of patients losing their sense of smell, NBC reports. It is less common than when delta was dominant, one doctor noted.
The Centers for Disease Control and Prevention still list new loss of taste or smell as a symptom of COVID, as well as fever or chills, coughing, shortness of breath, fatigue, muscle or body aches, headache, sore throat, congestion or runny nose, nausea or vomiting, and diarrhea.
Overall, symptoms for the subvariants of omicron, specifically BA.5, which now comprises the majority of COVID cases reported in the U.S., don’t yet seem much different from omicron, according to health officials.
While BA.5 and its fellow prominent omicron variant BA.4 have been described as having a “growth advantage,” they don’t appear to be more contagious either, early evidence suggests.
They do, however, seem better at evading immunity, meaning that even if you had omicron earlier this year, you aren’t necessarily protected from BA.4 or BA.5 like you may have been with earlier variants and subvariants. The variants have also been found to dodge protection offered by the vaccine.
Alix Martichoux contributed to this report.