The UKHSA found that those infected with the novel variety are less likely to develop severe symptoms or need hospitalisation.
It warned that the new strain is considerably more transmissible than previous versions like Delta, which caused a spike in hospital admissions.
Omicron is suspected to be infecting more people with Covid, with 9.5 percent of those infected having Covid previously.
HSA believes immunisation reduces Omicron protection.
A booster jab protects against symptomatic disease better than the initial two doses alone.
Its impact on preventing illness symptoms reduced by 15 to 25% after 10 weeks.
Most high-risk people got their booster eight to ten weeks ago.
But the HSA believes major disease protection would last longer.
M. Javid hailed the results as ‘promising' but cautioned caution over the Christmas period.
After Christmas, he said, it was too early to ‘determine next moves'.
"While two doses of the vaccine aren't enough, we know boosters offer significant protection against the variation," he said.
‘However, the variation continues to grow at an alarming rate, already exceeding the pandemic's daily record. Hospital admissions are rising, and the NHS cannot remain overburdened. This is an early analysis and we are monitoring the data hourly. For now, please be cautious this Christmas and obtain your booster as soon as possible to safeguard yourself and your family.'
The HSA says that compared to Delta, Omicron had a lower risk of hospitalisation.
Those with Omicron are up to 44% less likely than those with Delta to visit A&E, and up to 70% less likely to be hospitalised.
The findings resemble those made yesterday by experts at Scotland and London's Imperial College.
However, any benefit of a milder virus could be outweighed by a huge number of individuals contracting it.
The UK has set a new daily Covid record with 119,789 confirmed cases.
Omicron's influence on older age groups is also unknown, as majority of individuals infected and hospitalised are under 40.