World Health Organization experts have warned that repeating booster doses of the original Covid vaccines is not a viable strategy against emerging variants and called for new vaccines that better protect against transmission.
An expert group created by the World Health Organization to assess the performance of Covid-19 vaccines said simply providing fresh jabs of existing Covid vaccines as new strains of the virus emerge was not the best way to fight the pandemic.
"A vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be appropriate or sustainable," the WHO Technical Advisory Group on Covid-19 Vaccine Composition (TAG-Co-VAC) said in a statement.
The group said there could be a need to update the existing vaccines to better target emerging Covid variants, like Omicron which has spread rapidly and has been detected in 149 countries so far.
And it called for the development of new jabs that not only protect people who contract Covid against falling seriously ill but also better prevent people from catching the virus in the first place.
"Covid-19 vaccines that have high impact on prevention of infection and transmission, in addition to the prevention of severe disease and death, are needed and should be developed," TAG-Co-VAC said.
This, it said, would help lower "community transmission and the need for stringent and broad-reaching public health and social measures".
It also suggested that vaccine developers should strive to create jabs that "elicit immune responses that are broad, strong, and long-lasting in order to reduce the need for successive booster doses".
According to the WHO, 331 candidate vaccines are currently being worked on around the world.
Until new vaccines have been developed, the group said, "the composition of current Covid-19 vaccines may need to be updated".
This would "ensure that (they) continue to provide WHO-recommended levels of protection against infection and disease by VOCs (variants of concern), including Omicron and future variants".
Just weeks after Omicron was first detected in southern Africa, it is becoming increasingly clear that it is not only far more transmissible than previous variants, but also better at dodging some vaccine protections.
The WHO has so far given its stamp of approval to versions of eight different vaccines.
TAG-Co-VAC stressed that those vaccines provide a high level of protection against severe disease and death caused by the various variants of the virus.
It said preliminary data indicated the existing vaccines were less effective at preventing symptomatic Covid disease in people who have contracted the Omicron variant.
But protection against severe disease, which is what the jabs were especially intended to do, "is more likely to be preserved", it said.
"However, more data on vaccine effectiveness, particularly against hospitalisation, severe disease, and death are needed, including for each vaccine platform and for various vaccine dosing and product regimens," it said.
Over 50% of Europe may contract Omicron in weeks
Meanwhile, the World Health Organization's top Europe official said that more than half of Europe's population is expected to contract the Omicron Covid-19 variant within the next six to eight weeks.
Speaking at a press conference, regional director Hans Kluge warned that the Omicron variant represented a "new west-to-east tidal wave sweeping across" the European region.
"At this rate, the Institute for Health Metrics and Evaluation (IHME) forecasts that more than 50% of the population in the region will be infected with Omicron in the next six to eight weeks," Mr Kluge told reporters.
The WHO's European region comprises 53 countries and territories including several in Central Asia, and Mr Kluge noted that 50 of them had confirmed cases of the Omicron variant.
According to the WHO, 26 of those countries reported that over 1% of their populations were "catching Covid-19 each week," as of 10 January, and that the region had seen over seven million new virus cases reported in the first week of 2022 alone.
More than half of Europe's population is expected to contract the Omicron #Covid19 variant within the next six to eight weeks, according to a forecast cited by Hans Kluge, WHO Regional Director for Europe | https://t.co/mNS3lpcWmE pic.twitter.com/rCO6jvzZpg
— RTÉ News (@rtenews) January 11, 2022
Referencing data collected over the last few weeks, Mr Kluge said the variant was confirmed to be more transmissible and "the mutations it has enable it to adhere to human cells more easily, and it can infect even those who have been previously infected or vaccinated."
However, Mr Kluge also stressed that "approved vaccines do continue to provide good protection against severe disease and death, including for Omicron."
It comes as an Infectious Disease Specialist at the Royal College of Surgeons said he believes the Omicron wave in Ireland is beginning to level off, because the rate of increase is not as much today as it was a week ago.
However, Professor Sam McConkey warned that the challenge the healthcare sector is facing remains and the peak of that challenge could be yet to come.
"Because there is a delay of often a week or two, before people end up in hospital, we're not perhaps at that peak yet," he said.
Omicron may have higher 'asymptomatic carriage' - study
Preliminary findings from two South African clinical trials suggest the Omicron coronavirus variant has a much higher rate of "asymptomatic carriage" than earlier variants, which could explain why it has spread so rapidly across the globe.
The studies - one of which was carried out when Omicron infections were surging in South Africa last month and another which resampled participants around the same time - found a far greater number of people tested positive for the coronavirus but were not showing symptoms compared to previous trials.
In the Ubuntu study evaluating the efficacy of Moderna's Covid-19 vaccine in people living with HIV, 31% of 230 participants undergoing screening tested positive, with all 56 samples available for sequencing analysis verified to be Omicron.
"This is in stark contrast to the positivity rate pre-Omicron, which ranged from less than 1% to 2.4%," the researchers said in a statement.
In a subgroup of the Sisonke trial evaluating the efficacy of Johnson & Johnson's Covid-19 vaccine, the mean asymptomatic carriage rate rose to 16% during the Omicron period from 2.6% during the Beta and Delta outbreaks.
"The Sisonke study included 577 subjects previously vaccinated ... with results suggesting a high carriage rate even in those known to be vaccinated," the researchers said.
They added that the "higher asymptomatic carriage rate is likely a major factor in the rapid and widespread dissemination of the variant, even among populations with high prior rates of coronavirus infection".
South Africa experienced a surge in Covid-19 infections from late November, around the time its scientists alerted the world to Omicron.
But new cases have since fallen back and early indications are that the wave has been marked by less serious disease than earlier ones.
