If you battled a COVID-19 infection early in the pandemic, it probably won't protect you much from reinfection with omicron and its subvariants, a new study warns.

Even a previous infection with the original omicron variant provides little protection against reinfection, researchers report.

They said the findings from their study of more than 730 triple-vaccinated health care workers in the United Kingdom may help explain why omicron reinfection is so common, The Guardian reported.

"If you were infected during the first wave, then you can't boost your immune response if you have an omicron infection," study co-author Rosemary Boyton, a professor at Imperial College London, told the newspaper.

Boyton also noted that when "Omicron started flying around the country, people kept saying, that's OK, that will improve people's immunity," but "what we're saying is it's not a good booster of immunity."

It's believed that COVID variants such as omicron have mutations in their spike protein that help them evade immune responses, but these findings show the situation is more complex, according to co-author Danny Altmann, a professor at Imperial College London.

"It's actually worse than that, because the adaptations that the spike [protein] has now are actually inducing a kind of regulation or shutdown of immune response," he told The Guardian.

This study focused on omicron BA.1, but similar findings are likely for other omicron subvariants, Altmann noted.

Despite high rates of COVID-19 infection in the United Kingdom, low rates of hospitalizations and deaths suggest that vaccines still provide protection against severe disease and death, according to Altmann.

However, we're "not getting herd immunity, we're not building up protective immunity to omicron," he said. "So we face not coming out the other end of infections and reinfections and breakthrough infections."

The study was published June 14 in the journal Science.