A recent study led by Cornell University Qatar suggests that infection with the SARS-CoV-2 Omicron variant provides weak, short-term protection against reinfection, compared to earlier variants such as Alpha, Beta, and Delta. The researchers used a test-negative, case-control study design to compare the efficacy of Omicron infection against reinfection and poor outcomes in Qataris.
The study found that natural infection with Omicron provided only 53.6% protection against symptomatic or asymptomatic reinfection, with protection declining rapidly over time. In contrast, pre-Omicron infection offered robust protection against reinfection, with an estimated effectiveness of 81.1% regardless of symptoms.
The researchers attribute the decline in protection to the increased mutations in the spike gene of Omicron, which may lead to immune evasion and reduced efficacy of vaccines and treatments. The study highlights the need for periodic vaccine updates to sustain immunity in the face of evolving viral strains like Omicron.
Source: https://www.cidrap.umn.edu/covid-19/post-infection-immunity-may-wane-faster-after-sars-cov-2-omicron-after-previous-strains