COVID: WHO sees growing proof Omicron causes milder symptoms

A World Health Organization (WHO) official has said evidence is growing that the Omicron variant of the coronavirus is affecting the upper respiratory tract, which results in milder symptoms than previous strains.

“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,” WHO Incident Manager Abdi Mahamud told a media briefing in Geneva.

While hailing the potentially “good news”, Mahamud stressed that Omicron’s high transmissibility means it will become dominant within weeks in many places – thus posing a threat in countries where a high portion of the population remains unvaccinated.

His remarks on the reduced risks of severe disease chime with other data, including a recent study from South Africa. However, Mahamud also sounded a note of caution, calling the country an “outlier” since it has a young population among other factors.

Asked about whether an Omicron-specific vaccine was needed, Mahamud said it was too early to say but noted the decision required global coordination and should not be left to the commercial sector to decide alone.

A recent study, which is yet to be peer reviewed, showed that when compared with both Delta and the original coronavirus, the Omicron variant was quicker at getting into the upper airways and lungs, but much slower at infiltrating the lung tissue itself.

A combined United States and Japanese study – still under peer review – found that rodents that were infected with Omicron had less lung damage, lost less weight and were less likely to die than those infected with Delta.

Meanwhile, a team studying the Omicron variant in Glasgow believe this variant is unable to infect the lung cells as much, because an essential protein that usually helped previous SARS-COV-2 variants to gain entry into the lung cells bound less strongly to Omicron.

Commenting on the findings, NHS doctor Amir Khan wrote on Monday that because it is hypothesised serious illness from COVID-19 occurs once the virus gets into the lungs, “there is much less chance of severe disease” if it “can be contained in the upper airways, the mouth, nose, etc”.

Still, he added: “It is widely accepted that even if the variant is milder, the sheer number of people it infects might lead to more hospitalisations overall, with healthcare workers having to isolate due to testing positive.”