All three US-authorized Covid-19 vaccines appear to be significantly less protective against the newly-detected Omicron variant of the coronavirus in laboratory testing, but a booster dose likely restores most of the protection, according to a study released on Tuesday.

The study from researchers at Massachusetts General Hospital (MGH), Harvard and MIT that has not yet been peer-reviewed tested blood from people who received the Moderna, Johnson & Johnson and Pfizer/BioNTech vaccines against a pseudovirus engineered to resemble the Omicron variant.