The German-made BioNTech vaccine is far less effective at neutralising the Omicron variant of the coronavirus but a booster shot greatly improves protection, a Hong Kong research team has found.
Receiving jabs remained the most effective protection against Covid-19, said the researchers from the University of Hong Kong and Chinese University who carried out the study and released their findings on December 12.
The Omicron variant reduced the antibodies of the BioNTech vaccine by at least 32 times, according to the research. Data from a study involving the Chinese-made Sinovac vaccine, the other jab offered in the city, will soon be available.
The team noted that previous studies had shown Sinovac to be less effective in generating virus-killing antibody levels against other variants, which they expected to be true of Omicron as well.
"We expect that vaccines may still have a protective effect against severe disease and death," said Chinese University respiratory expert Professor David Hui Shu-cheong, who is also a government pandemic adviser. "It is therefore important that all those who are eligible for vaccination get fully vaccinated."
The study found blood taken from 10 people vaccinated with two BioNTech shots a month earlier was at least 32 times less effective in killing off the Omicron variant.
"We can see most individuals had high levels of virus-killing activity against the original Sars-CoV-2, but this ability was markedly reduced by 32-fold or more against the Omicron variant," HKU virologist Professor Malik Peiris said.
The neutralising antibodies had dropped from 320 units to 10 for the original virus and Omicron respectively. At least 25 units are needed to confer protection against infection. A booster shot raised the vaccine's effectiveness to 75.5%, South China Morning Post. reported.
"It will be important for those who are at higher risk, including older age and those with immunocompromised conditions or other chronic diseases, such as diabetes and high blood pressure, to take booster doses of vaccine as soon as possible," Peiris said.
