Some Albertans at risk of catching COVID-19 twice, infectious disease doctor says

Even if you've already had COVID-19, you're not invulnerable, an Alberta infectious disease expert says, as some people are catching the virus for a second time. 

The new subvariant of Omicron, which has become the dominant strain in Alberta, can create breakthrough infections in people who have already had the virus.

While reinfections are possible, immunity due to vaccines and antibodies from previous infection are keeping many people from severe illness, said Craig Jenne, an associate professor at the University of Calgary department of microbiology, immunology and infectious diseases. 

"The good news, though, is that many of these reinfections do lead to milder disease. So it's something we have to watch for, but in general, it's not necessarily something to be panicking about at this moment," he said. 

Dr. Lynora Saxinger, infectious diseases physician at the University of Alberta, said reinfections can happen in a similar way to a vaccine breakthrough.

"You have had an immune response to this. And then, for whatever reason, that immune response isn't fully protective," she said.

However, a COVID infection can have a "self-boosting" effect, she noted. 

And for those who caught COVID-19 during the Alpha or Delta waves, there is a "fairly significant risk of reinfection," she said. 

Though the combination of prior infection and vaccination is quite strong, Saxinger said it's possible for those who contracted Omicron to get sick with the virus's subvariant — but it is extremely rare. 

"No one is going to be invincible," she said, but in addition to milder cases in those who have been reinfected, vaccination also reduces the risk of hospitalization or death. 

"It's just all an odds game now. And your own particular risk is a summary of your vaccinations and infections and behaviours."