Studies Find Pfizer Vaccine Less Effective Against Omicron

Health officials and vaccine makers call for boosters after studies show Pfizer vaccine is less effective against Omicron, but data on breakthrough cases suggest the vaccine hasn’t been effective against other strains, either.

Three studies released within days of each other show the Pfizer-BioNTech COVID vaccine is less effective against the Omicron variant.

According to a preprint study by researchers at the UK’s University of Oxford in England, there’s “a substantial fall in neutralization” of antibodies in the fully vaccinated “with evidence of some recipients failing to neutralize at all.”

The Oxford researchers concluded AstraZeneca’s COVID vaccine — available in the UK but not the U.S. — is also less effective against Omicron.

According to the study:

“This will likely lead to increased breakthrough infections in previously infected or double-vaccinated individuals, which could drive a further wave of infection, although there is currently no evidence of increased potential to cause severe disease, hospitalization or death.”

The study’s lead author, Gavin Screaton, Ph.D., who also is head of Oxford’s Medical Sciences Division, said Monday in a press release:

“These data will help those developing vaccines, and vaccination strategies, to determine the routes to best protect their populations, and press home the message that those who are offered boostervaccination should take it.

“Whilst there is no evidence for increased risk of severe disease, or death, from the virus amongst vaccinated populations, we must remain cautious, as greater case numbers will still place a considerable burden on healthcare systems.”

Dr. Matthew Snape, co-author of the study, said in the release:

“Importantly, we have not yet assessed the impact of a ‘third dose’ booster, which we know significantly increases antibody concentrations, and it is likely that this will lead to improved potency against the Omicron variant.”

The U.K.’s Health Security Agency last week estimated two doses of a COVID vaccine were significantly less effective at preventing symptomatic disease through infection from the Omicron variant compared to Delta.

However, the agency noted that after a booster dose, vaccines were thought to be 70% to 75% effective at preventing symptomatic infections.

Commenting on the predictions that boosters would be useful in combating Omicron, Brian Hooker, Ph.D., P.E., Children’s Health Defense chief scientific officer and professor of biology at Simpson University, told The Defender:

“The point they are trying to make is that waning immunity from the two-dose series is ineffective against the Omicron variant, but an up-to-date booster would increase protection to 70% to 75% — which is still very ‘leaky’ for a vaccine.”

Hooker added: “I believe this is more propaganda and wishful thinking than truth, given the sparse data regarding boosters and Omicron.”

Hooker said the lack of data from the Centers for Disease Control and Prevention (CDC) regarding vaccine effectiveness in general is “at a minimum disconcerting” and probably means that waning effectiveness of the vaccines is leading to a significant increase in breakthrough cases and deaths in the fully vaccinated.

“The whole thing is extremely confusing, given the admission of the CDC earlier that they count only those breakthrough cases that lead to hospitalization and death. This renders the whole analysis meaningless,” Hooker said.

In May, the CDC stopped tracking breakthrough cases that didn’t result in hospitalization or death. The CDC also states that “partially vaccinated,” or those with one dose of Pfizer or Moderna, are excluded from the breakthrough case data.

CDC data from early October showed 30,177 fully vaccinated patients, defined as two weeks after the second Pfizer or Moderna shot or one Johnson & Johnson shot, had died or were hospitalized.

The CDC’s COVID data tracker states “data will be updated monthly,” however the data hasn’t been updated since Oct. 2.

More studies showing Pfizer ineffective against Omicron spur more calls for boosters

preprint study posted Saturday by the Africa Health Research Institute showed the Pfizer shot is 22.5% effective in combating the Omicron variant. 

The South African researchers were the first to show the variant, found by scientists in South Africa and Botswana and announced on Nov. 25, could largely, but not totally, escape the antibodies produced by Pfizer’s vaccine. “Still, they said a booster shot could increase immunity,” Bloomberg reported.

And a real-world study published Tuesday by South Africa’s largest private health insurance administrator, Discovery Health, found Pfizer’s vaccine was less effective in South Africa at keeping people infected with the virus out of hospital since the Omicron variant emerged last month.

According to Reuters, the Discovery Health study showed between Nov. 15 and Dec. 7, people who received two doses of the shot had a 70% chance of avoiding hospitalization, down from 93% during the previous wave of Delta infections, the study showed.

When it came to avoiding infection altogether, the study showed protection against catching COVID had slumped to 33% from 80% previously.

All three studies follow a trend of the vaccines being found to be less effective against variants than against the original Wuhan strain.

For example, earlier studies showed the Pfizer vaccine to have waning effectiveness against the Delta variant. And in August, a study found the Pfizer vaccine to be only 42% effective as the Delta variant was starting to circulate.

Omicron cases on the rise, but most are mild 

According to a report from hospitals in the Tshwane District of South Africa, early data on Omicron show there’s been an “exponential rise in cases,” but “the majority of hospital admissions are for diagnoses unrelated to COVID-19…. The SARS-CoV-2 positivity is an incidental finding in these patients and is largely driven by hospital policy requiring testing of all patients requiring admission to the hospital.”

The findings also suggest Omicron is milder than previous variants:

“A significant early finding in this analysis is the much shorter average length of stay of 2.8 days for SARS-CoV-2 positive patients admitted to the COVID wards over the last two weeks compared to an average length of stay of 8.5 days for the past 18 months. The NICD (National Institute for Communicable Diseases) reports a similar shorter length of stay for all hospitals in Tshwane in its weekly report. It is also less than the Gauteng or National average length of stay reported by the NICD in previous waves.”

As The Defender reported last week, Dr. Angelique Coetzee, who is credited with discovering the Omicron variant and who chairs the South African Medical Association, said Omicron symptoms so far appear mild.

Writing in The Daily Mail, Coetzee said:

“No one here in South Africa is known to have been hospitalized with the Omicron variant, nor is anyone here believed to have fallen seriously ill with it … The simple truth is: We don’t know yet anywhere near enough about Omicron to make such judgments or to impose such policies … If, as some evidence suggests, Omicron turns out to be a fast-spreading virus with mostly mild symptoms for the majority of the people who catch it, that would be a useful step on the road to herd immunity.”

Nference, a data analytics firm from Cambridge, Massachusetts, conducted a study suggesting omicron might have acquired a mutation with a piece of the common cold. 

Reuters reported:

“This could mean the virus transmits more easily, while only causing mild or asymptomatic disease. Scientists do not yet know whether Omicron is more infectious than other variants, whether it causes more severe disease or whether it will overtake Delta as the most prevalent variant. It may take several weeks to get answers to these questions.”