New Delhi, Jan 22, 2022: Amid the rapid spread of the Omicron variant of coronavirus across the world, three new studies by the US Centers for Disease Control and Prevention (CDC) have highlighted that booster doses can reduce hospitalisation risk by 90 per cent against Omicron.
These are the first large studies in the US to look at vaccine protection against Omicron. The studies, which were published on Friday, also highlighted that unvaccinated people were at the highest risk of getting infected with Covid-19 and could be hospitalised with severe symptoms.
The premise of the studies is that mRNA vaccine effectiveness (VE) in preventing Covid-19 decline because of waning of vaccine-induced immunity.
The first study looked at nearly 88,000 hospitalisations across 10 US states from August 2021 till now. The study found that while getting two vaccine shots was 57 per cent effective at preventing hospitalisations against Omicron, the booster dose provided better immunity at 90 per cent when it had been at least six months after the second shot.
Also, booster doses were 82 per cent effective at preventing visits to emergency rooms and urgent care centers. In comparison, two doses only provide 38 per cent effective when taken at least six months past the second shot.The second study looked at the Covid-19 case count and the death rates in 25 US states from April 4 to December 25, 2021. The study showed that individuals who had taken the booster dose were less likely to get infected with Omicron.
The study found that out of a sample population of 100,000 people, there were 149 cases among boosted individuals while there were 255 cases among people who took two doses of Covid-19 vaccine.
The third study, involving CDC scientists, was published in medical journal Journal of the American Medical Association (JAMA). The study found that people who took the booster dose were 67 per cent less likely to develop symptomatic infection. However, two doses offered no significant protection against omicron when measured several months after completion of the original series, the study said.
Even as booster doses have shown improved vaccine effectiveness against Covid-19, there could still be some cases of breakthrough infection due to Omicron. A study published in the Lancet showed that in some cases, people who had taken three doses of Covid-19 vaccine were infected by the Omicron variant.
However, the study also showed that full vaccination followed by a booster dose still provides good protection against severe disease caused by Omicron.
India rolled out booster doses, or precautionary doses, against Covid-19 for people above 60 years of age, health workers and frontline workers from January 3.
Courtesy: India Today