Early data indicates the Omicron coronavirus variant may more easily reinfect people who have already had the virus or been vaccinated than previous variants, but could also cause milder disease, the World Health Organization said.
“Emerging data from South Africa suggests increased risk of reinfection with Omicron,” WHO chief Tedros Adhanom Ghebreyesus told reporters on Wednesday, adding “there is also some evidence that Omicron causes milder disease than Delta”.
But he stressed more data was needed before drawing firm conclusions, and urged countries everywhere to boost their surveillance to help provide a clearer picture of how Omicron is behaving.
The hopeful assessments came as global concern grew over the heavily mutated variant, which has forced dozens of nations to reimpose border restrictions and raised the possibility of a return to economically punishing lockdowns.
Even if it does turn out that Omicron causes less severe disease, Tedros warned against slacking off vigilance against the virus. “Any complacency now will cost lives,” he warned.
WHO emergencies director Michael Ryan agreed, pointing out that so far the data indicates the variant is “efficiently transmitting, and probably more efficiently transmitting even than the Delta variant”.
“That does not mean that the virus is unstoppable,” he said. “But it means the virus is more efficient at transmitting between human beings. And, therefore, we have to redouble our efforts to break those chains of transmission to protect ourselves to protect others.”
‘More people die’
Even if the new variant turns out to be less dangerous than many previous variants, if it transmits more rapidly it could still sicken more people, overburden health systems, “and more people die”, he said.
The WHO experts stressed the importance of vaccination, highlighting even if vaccines prove less effective against Omicron, as some data indicates, they are still expected to provide significant protection against severe disease.
Chief WHO scientist Soumya Swaminathan cautioned against knee-jerk reactions to early studies hinting the Pfizer-BioNTech vaccine may have reduced efficacy against the new variant.
She pointed out the studies done so far were small and the reduction in the “neutralising activity” varied dramatically between different studies, from four to five-fold in some experiments to up to 40-fold in others.
They also only looked at the neutralisation of antibodies when “we know the immune system is much more complex than that”, she said.
“So I think it’s premature to conclude that this reduction neutralising activity would result in a significant reduction in vaccine effectiveness. We do not know that.”