A joint study by two local universities has found that the antibody levels in people who have been vaccinated and infected with the Omicron BA.2 strain of Covid is higher, when compared to those who are triple jabbed and have never been infected.

Their antibody levels, known as geometric mean antibody titres or GMT, were measured at 36.9, while those who had three doses of BioNTech were 20.7 and just 5.4 for those who were inoculated with Sinovac.

One hundred and four people were recruited by the Chinese University and the University of Hong Kong to take part in the study.

"In such breakthrough infection, it can help you to generate cross-reactive antibody response, which can recognise multiple SARS-Coronavirus-2 variants. That may help you to prepare for the next," said Leo Poon from HKU's School of Public Health.

"May be in the near future, you will encounter new subvariants or variant-of-concerns, your antibody response seems to be better than before. That may help you to reduce the chance of having severe clinical outcome or die from the infections."

Poon explained that the current BioNTech and Sinovac vaccines didn't react well with BA.5 because they were designed to combat the original Covid strain. But he said real life data suggests the vaccines still offer good protection against severe complications.