Boosters and Omicron: There is a substantial reduction in risk of hospitalisation for Omicron cases after three doses of vaccine compared to those who are unvaccinated


Protection of COVID-19 vaccination and previous infection against Omicron BA.1 and Delta SARS-CoV-2 infections, the Netherlands, 22 November 2021- 19 January 2022

Stijn P. Andeweg, View ORCID ProfileBrechje de Gier, Dirk Eggink, Caroline van den Ende, Noortje van Maarseveen, Lubna Ali, Boris Vlaemynck, Raf Schepers, RIVM COVID-19 surveillance and epidemiology team, Susan J. M. Hahne, Chantal Reusken, Hester E. de Melker, Susan van den Hof, Mirjam J. Knol


This article is a preprint and has not been certified by peer review [what does this mean?]. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.



Given the emergence of the SARS-CoV-2 Omicron BA.1 variant and the roll-out of booster COVID-19 vaccination, evidence is needed on protection conferred by primary vaccination, booster vaccination and previous SARS-CoV-2 infection against Omicron BA.1 compared with Delta infection. We employed a test-negative design and used multinomial logistic regression on data from community PCR testing in the Netherlands, from 22 November 2021 to 19 January 2022. S-gene target failure (SGTF) was used as proxy for Omicron BA.1 infection versus Delta. A total of 528,488 tests were included, of which 38,975 SGTF and 41,245 non-SGTF infections. Protection from primary vaccination was 25% (95% confidence interval (CI): 21-29) and from previous infection 33% (95% CI: 31-35) against Omicron BA.1 infection. Protection against Delta infection was higher with 76% (95% CI: 75-76) for primary vaccination and 78% (95% CI: 76-80) for previous infection. Higher protection was observed in individuals with both primary vaccination and earlier infection compared with either one. Waning of vaccine- or infection-induced protection over time was observed against both variants. Booster vaccination considerably increased vaccine effectiveness against Omicron BA.1 to 76% (95% CI: 72-79) and 68% (95% CI: 67-69) with and without previous infection, respectively. Primary vaccination with current COVID-19 vaccines and pre-Omicron SARS-CoV-2 infections offer low protection against Omicron BA.1 infection. Booster vaccination considerably increases protection against Omicron BA.1, although protection remains lower than against Delta.



Booster Can Boost Effectiveness Against Omicron To 88%, UK Studies Show

Covid Booster Dose: The findings compiled in a report by the UK Health Security Agency (UKSHA) show significantly higher protection provided by third vaccine dose.

WorldPress Trust of IndiaUpdated: January 03, 2022 2:06 pm IST


A third dose of COVID-19 vaccine can provide up to 88 per cent protection against hospitalisation from infection by the Omicron variant of coronavirus, according to early results from studies conducted in the UK.

The findings compiled in a report by the UK Health Security Agency (UKSHA) show significantly higher protection provided by third vaccine dose against the highly mutated variant first identified in Botswana and South Africa in November, compared to two doses.

Eric Topol, professor of molecular medicine, and director of the Scripps Research Translational Institute in the US noted that vaccine effectiveness drops to 52 per cent against Omicron around six months after taking the second shot of a COVID-19 vaccine.

However, a booster dose substantially increases immunity and lowers the odds of being hospitalised with COVID-19 infection.

“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,” Topol tweeted on Sunday.

“It’s pretty impressive that vaccines directed to the ancestral strain spike from 2 years ago, with the virus that’s evolved through more than 290 million confirmed cases, and now to the hyper-mutated Omicron, have preserved efficacy of near 90 per cent vs severe disease with a 3rd shot,” he said in another tweet.

The UKHSA report cited two studies which examined the association between both variant and vaccination status and risk of hospitalisation.

The first study is based on approximately half a million Omicron cases, and includes all age groups while the second one uses a smaller dataset and is restricted to ages 18 and over.

The first study confirms the previous finding of reduced overall risk of hospitalisation for Omicron compared to Delta variant.

Both the studies found a substantial reduction in risk of hospitalisation for Omicron cases after three doses of vaccine compared to those who are unvaccinated.

After three doses of vaccine, the risk of hospitalisation for a symptomatic case identified with Omicron through community testing was estimated to be reduced by 68 per cent when compared to similar individuals with the variant who were not vaccinated.

“Combined with the protection against becoming a symptomatic case, this gives a vaccine effectiveness against hospitalisation of 88 per cent (78 to 93 per cent) for Omicron after three doses of vaccine,” the UKHSA report added.



If Your Time is short

  • A Danish study shows a sharp drop in vaccine effectiveness over time against the omicron variant of COVID-19 in people with two doses of the Pfizer or Moderna vaccine.
  • But it also shows protection is quickly restored with a Pfizer booster dose. There was not enough data about a Moderna booster.
  • The study’s authors said that their findings prove a need to ramp up vaccination and booster doses to fight the variant.


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