Updated on: Sunday, January 02, 2022, 04:59 PM IST

COVID-19: Third dose can boost vaccine effectiveness against Omicron to 88%, show UK studies

 (Photo by Ben STANSALL / AFP)

(Photo by Ben STANSALL / AFP)


As Omicron's threat continues to reel over the world, new studies conducted in the UK have found that a third dose of Covid-19 vaccine can boost a person’s resistance to the variant of coronavirus by as much as 88 per cent.

Sharing a UK Health Security Agency (UKHSA) report compiling the findings of these studies, Dr Eric Topol, professor of molecular medicine and director of the Scripps Research Translational Institute, pointed out that vaccine effectiveness drops to 52 per cent against Omicron around 6 months after taking the second shot of a Covid-19 vaccine.

“That's a big boost of protection for 3rd dose vaccine vs hospitalisation from Omicron infection. Vaccine effectiveness increased from 52 per cent (due to 2-dose waning after 6 months) to 88 per cent after the 3rd dose,” Dr Eric Topol said in a tweet.

However, a third or booster dose substantially shoots up immunity and lowers the odds of contracting a Covid infection with serious symptoms that could lead to hospitalisation.

This is a significantly higher degree of protection against the latest mutated strain when compared to second dose, whose effectiveness begins to wane after a period of six months.

The UKHSA report does mention studies pointing to lower vaccine effectiveness against Omicron as compared to the Delta variant. However, it conclusively indicates that risk of emergency care or hospitalisation in Omicron cases was half of that for Delta.

Furthermore, the risk of hospitalisation is lower for Omicron cases after a second and third vaccine dose, with an average of 81 per cent reduction in the risk of hospitalisation after three doses as against unvaccinated patients.

The studies also showed that among those who had received two doses of AstraZeneca, there was no effect against Omicron from five months after the second dose.

While those who had received two doses of Pfizer or Moderna, vaccine effectiveness dropped from around 65 to 70 per cent down to around 10 per cent by six months after the second dose.


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Published on: Sunday, January 02, 2022, 04:59 PM IST