NEW DELHI: Full vaccination against Covid-19 or previous infection may not offer any substantial protection against the highly contagious Omicron variant of SARS-CoV-2, but its hospitalisation rate is way low at less than 4%.These were the takeaways from India’s first epidemiological study on Omicron carried out by researchers associated with a leading government hospital.
Their results, released on a pre-print repository of medical science, have also shown that Omicron was already in community circulation in Delhi in December — days after South Africa alerted the world about the variant — and underlined the limited impact of airport screening or curtailing flights from other countries.
Researchers associated with the Institute of Liver and Biliary Sciences in Delhi sequenced the genomes of 264 Covid-19 positive samples from five districts across the national capital and found 82 of them had Omicron. The rest were infected with the Delta variant that had fueled the devastating second Covid wave in India last summer. Though the sample size is small, the study is being viewed as a representative analysis of Omicron-driven surge in many parts of India.
The analysis of 264 patients who had tested positive between November 25 and December 23 last year found that 72 (or 88%) of the Omicron-infected patients had been fully vaccinated with either Covishield or Covaxin. Another patient had received two doses of the Moderna vaccine and a third dose of Covaxin. Only three among the Omicron patients required hospitalisation, and each had other underlying health conditions such as diabetes or high blood pressure. None of them needed ICU care.
Hospitalisation rates during the earlier Covid-19 waves in India were 20-23%. Experts pointed out that the lower hospitalisation rates for Omicron documented in Delhi are in line with observations in South Africa, the UK and various other countries.
Baseline characteristics of Omicron cases
Male 57.3%
Female 42.7%
Vaccination status
Vaccinated 87.8%
Not Vaccinated 12.2%
Travel history
Yes 39.1%
No 60.9%
Previous SARS-CoV-2 infection confirmed by RT-PCR
Yes 17.1%
No 83.9%
Clinical features
Asymptomatic 61%
Symptomatic 39%
Comorbidities 18.3%
No comorbidities 81.7%
Hospitalisation 3.6%