Spain has reported more COVID-19 reinfections in a recent span of two weeks than it has during the rest of the pandemic, according to the latest data from a Spanish public health research institute.

Data from the Carlos III Health Institute shows there were 20,890 repeat infections reported in Spain from Dec. 22, 2021, to Jan. 5, 2022. That figure tops the 17,140 reinfections reported in the European country from the start of the pandemic in March 2020 to Dec. 22, 2021. The data includes confirmed, probable and possible cases.

Alfredo Corell, an immunology professor at Spain's University of Valladolid, told Spanish news site NIUS that the rising number of reinfections were due to the new and highly transmissible omicron variant.

"Prior to this variant, reinfections were anecdotal at the global level," Corell told NIUS. "Omicron has changed this paradigm."

In southern Africa, where the variant was first identified in November, preliminary research suggests that omicron is three times more likely to cause reinfections compared to other known variants of the virus, including the highly contagious delta. However, symptoms of reinfected individuals appear to be mild, according to Anne von Gottberg, a microbiologist at South Africa's National Institute for Communicable Diseases who is studying omicron.

"Previous infection used to protect against Delta," von Gottberg said during a press briefing on Dec. 2. "But now, with Omicron, that doesn't seem to be the case."