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Pfizer, AstraZeneca vaccines less effective against Omicron variant – Report


As nations remain alert on the Omicron variant of SARS-CoV-2, the coronavirus that causes Covid-19, a report has suggested that two doses of Pfizer and AstraZeneca’s Covid-19 vaccines have partial effect on the new threat.

The new variant has placed some European countries, including the United Kingdom that has recorded a death from Omicron, on red alert with border restrictions being effected against some countries, including Nigeria.

Although the vaccines proved safe and highly effective at preventing deaths and hospitalisations against pre-Omicron variants, IndiaToday reports that researchers discovered that compared to other variants, antibodies of fully vaccinated appeared to be lower compared to other variants including Delta.

As such, fully vaccinated people are advised, according to the study, to get booster shots.

The yet to be peer-reviewed study published in pre-print on medRxiv revealed that samples collected one, three, and six months after the two doses of Pfizer-BioNTech vaccine showed a limited ability to neutralise SARS-CoV-2. However, four weeks after a third dose, neutralising antibody titres are boosted.

In another study, researchers noted a 30-fold drop in neutralising antibodies against Omicron as compared to Delta after two doses of the Pfizer and AstraZeneca vaccines.

“We’re hopeful that the current vaccine will protect against severe disease and hospitalisation and that’s certainly what we’ve seen before with other variants of concern,” said Teresa Lambe, one of the creators of the shot that Astra developed with Oxford told Bloomberg.

“We and other vaccine manufacturers are in a position that if a new variant vaccine is needed, we can go fast,” said Teresa Lambe.

Billy Gardner and Marm Kilpatrick from the University of California, Santa Cruz, through self-developed computer models based on data on efficacy results of Covid-19 vaccines found that efficacy against symptomatic infection from Omicron is only about 30 per cent, down from about 87 per cent against Delta.

Booster doses restored protection to about 48 per cent. “[It] is similar to the protection of individuals with waned immunity against the Delta variant (43 per cent),” Kilpatrick said.

He said, “We estimated that protection against severe disease was 86 per cent for recent mRNA vaccination against Omicron, 67 per cent for waned immunity, and 91 per cent following third dose boosters. There are still no direct estimates of vaccine effectiveness for severe disease from any country yet, so our estimates cannot be compared to direct estimates yet.”