Re-infection Risk 5 Times Higher with Omicron

Omicron variant
Source: Freepik

A recent report has found that reinfection risk is 5.4 times higher with Omicron than the Delta variant.

Recently, a team of researchers at the Imperial College London conducted a study estimating the growth, population distribution and immune escape of Omicron in England. The team looked at factors associated with Omicron infection and its impact on vaccine effectiveness. Moreover, they assessed reinfection risk with the Omicron variant and compared it to the Delta strain.

Quantifying reinfection risk and vaccine effectiveness against Omicron is essential for modelling the likely future trajectory of the Omicron wave and the potential impact of vaccination and other public health interventions.

Professor Azra Ghani, Imperial College London

According to the report, researchers analyzed all COVID-19 cases between 29th November and 11th December. The team not only included cases with an S gene target failure, but also those identified through genotype analysis. People infected with the Omicron variant typically show an S gene target failure on routine PCR tests; while, those infected with another variant do not.

Limited Data

Results showed 5.4 times higher reinfection risk with Omicron as compared with Delta. The researchers also found an increased growth in Omicron cases. However, due to limited hospitalization data, the report could not give an accurate assessment of Omicron’s severity. Previously, a study had suggested that the new variant causes only mild infections among people.

The report further looked at Omicron infection risk following COVID-19 vaccination. Vaccine effectiveness following two standard doses was only 0 to 20% against the new variant. Whereas a booster dose increased this to between 55% and 80%.

This level of immune evasion means that Omicron poses a major, imminent threat to public health.

Professor Neil Ferguson, Imperial College London

Although the report provides evidence of Omicron’s ability to evade vaccines, previous studies have shown that booster doses provide adequate protection against the variant. Recently, Pfizer and BioNTech released data showing three doses of their vaccine effective at producing neutralizing antibodies against Omicron. Therefore, vaccination remains the best measure against COVID-19.

Source: Imperial College London


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