The omicron variant and covid-19 reinfection risk

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PRELIMINARY results from lab studies were released this week showing that the Omicron coronavirus variant is able to evade some of the protection against infection offered by COVID-19 vaccines.

Boosters, though, may hold up better, according to data from Pfizer and BioNTech. Many experts also think two doses of a vaccine will protect against severe illness, even against Omicron.

“Early information definitely supports that there are enough mutations in the right place in the Omicron variant to escape the maximal benefits of the vaccine,” said Dr. Shira Abeles, an infectious disease specialist at UC San Diego Health.

“But we are optimistic there will be partial protection. So yes, we may be more easily infected, but we remain optimistic that it won’t result in [a large increase in] hospitalizations and deaths.”

But how well will a previous coronavirus infection protect against this new variant? One study suggests that, in the face of Omicron, people who’ve recovered from a prior infection have a significant risk of reinfection — much higher than with earlier variants. A preprint study from South Africa found that the risk of reinfection during the recent Omicron wave is substantially higher than the risk seen during the country’s earlier Beta and Delta surges.

Researchers used the country’s extensive records of COVID-19 tests from March 2020 through late November 2021 to estimate the reinfection risk with Omicron.

They found that the risk of infection remained stable during the earlier surges caused by Beta and Delta, but increased dramatically since the arrival of Omicron.

“We find evidence of increased reinfection risk associated with emergence of the Omicron variant, suggesting evasion of immunity from prior infection,” study author Juliet Pulliam, PhD, who directs the South African DSI-NRF Centre for Excellence in Epidemiological Modelling and Analysis at Stellenbosch University, wrote on Twitter.

Recent reinfections occurred in people whose original bout with the virus happened during the previous waves, but mostly from people who had a previous infection during the Delta wave.

 

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