Covid-19: Could the Omicron variant cause milder illness?

The coronavirus’ Omicron variant that has now been detected in over 30 countries has prompted fears it could significantly undermine the effectiveness of Covid-19 vaccines.

Yet, amid a race to understand the consequences of the variant, some scientists are also looking to see if this mutation might cause milder illness than its predecessors. However, while they have cautioned that it was too early to draw conclusions, here is what has emerged so far:

What the data shows
Evidence from initial cases is limited. Among Europe’s cases that included information on disease severity, half the patients were asymptomatic while half had mild symptoms, the European Centre for Disease Prevention and Control said in a report.

There were no instances of severe disease, hospitalisation, or death. However, the agency said it would require data from hundreds of cases to assess disease complications accurately and estimated that it could take several weeks. Additionally, most cases in Europe so far have been in fully vaccinated younger people, making them less likely to suffer severe illness.

In South Africa, where the daily number of Covid-19 cases doubled to 8,561 on Wednesday, symptoms for re-infected patients and those infected after vaccination seem to be mild.

Emory University, Atlanta, Infectious Diseases Expert Dr Carlos Del Rio told Reuters that evidence from South Africa suggested that it might cause milder illness. However, he cautioned that a lot of patients in South Africa initially were young university students.

Omicron a ‘less fit’ version of the coronavirus?
As data on real-world infections emerges, scientists are studying the variant in the laboratory to decipher it. The Omicron variant has around 50 mutations not seen in combination before, including over 30 on the spike protein the virus uses to attach to human cells. Vaccines currently being used target that spike protein.

Penn Institute for Immunology Director Dr John Wherry told Reuters typically when viruses accumulated a lot of mutations, they lost some fitness. Certain mutations of the Omicron may impair the virus’ ability to cleave, changing the spike protein’s behaviour, he said.

Some scientists have put forward a theory that the Omicron variant might have developed over months in an immunocompromised individual, such as an HIV patient in southern Africa. Wherry said if that was the case, the virus adapted not to kill the host.

There are other theories that the variant evolved from an animal host.

Omicron to become the dominant variant?
The other question surrounding the Omicron variant is if it will overtake the Delta variant, which accounts for the overwhelming majority of infections across the globe. If the Omicron variant does become dominant, but causes milder illness, it could become a turning point toward the virus becoming a seasonal threat such as influenza, Sumit Chanda, an infectious disease researcher at San Diego’s Scripps Research Department of Immunology and Microbiology, told Reuters.

The European Union’s public health agency on Thursday said the Omicron variant could cause over half of all Covid-19 infections in the continent within a few months.

While research into the Omicron variant is underway, disease experts said people must stay vigilant by getting either initial vaccinations or booster shots, apart from wearing masks in indoor or crowded settings, washing hands, and ventilating rooms.