: A COVID-19 recovery offers low protection against omicron variant but boosters are effective, London study finds
The omicron variant of the coronavirus that causes COVID-19 evades immunity from past infection or from two doses of a vaccine, according to a new research report from England published on Friday.
The study, which has not been peer-reviewed, was conducted by the COVID-19 research team at Imperial College London, and used data from the health authorities on all PCR-confirmed cases of the virus in England based on tests conducted between Nov. 29 and Dec. 11.
The study found that the risk of reinfection with omicron is 5.4 times greater than that associated with the delta variant, which is still the dominant one in the U.S.
A COVID-19 recovery offers about 19% protection against omicron, while two vaccine doses offer 20% protection, researchers found. A booster dose raises that number to 55% to 80%.
Researchers found that omicron cases were doubling every two days up to Dec. 11, and that its R number, or rate of reproduction, was above 3 in that period. That means that each person with COVID is likely to infect more than three others.
The distribution by age, region and ethnicity also differs from delta, with omicron infecting far more people aged 18 to 29, residents in London and those of African ethnicity. “London is substantially ahead of other English regions in Omicron frequency,” the report found.
What the study did not find is whether omicron is more or less severe than delta, based either on symptoms or on the number of patients needing hospital care, although the authors acknowledged that the data “remains very limited at this time.”
It did, however, find a “significantly increased risk” of developing a symptomatic case of COVID for people two or more weeks after a second vaccine dose, and two or more weeks past a booster dose, in the case of the Pfizer PFE, -1.58% and AstraZeneca AZN, -1.14% AZN, +0.53% vaccines. The AstraZeneca vaccine has not been granted emergency use authorization in the U.S.
“This study provides further evidence of the very substantial extent to which omicron can evade prior immunity given by both infection or vaccination. This level of immune evasion means that omicron poses a major, imminent threat to public health,” said Professor Neil Ferguson, vice dean for academic development in the Faculty of Medicine, at Imperial College London.
Earlier this week, the World Health Organization said omicron remains a very high risk as it spreads rapidly across the globe, but that there was too little data to be certain it is more lethal than other variants. The agency also said it seems more resistant to existing vaccines, but that boosters seem to improve protection.
South Africa, where scientists were first to bring attention to omicron in late November, has so far reported mostly mild cases with fewer hospitalized patients requiring oxygen than with previous cases. However, some experts say the country may have extra immunity because so many people have had the illness.
The UK set another record one-day COVID-19 case tally on Friday, with government data counting 93,045 positive cases, the most since the start of the pandemic. It’s the third straight day that cases have set records as the omicron variant races across the country.
The UK has seen 477,229 new cases in the last seven days, the data shows.