New York, December 15: Vaccines developed by US drugmakers Pfizer, Moderna, Johnson and Johnson against Covid-19 have been shown to be less effective against the new supermutant Omicron variant, which has now spread to 77 countries.
The omicron variant, which contains up to 36 mutations in spike protein, is known to avoid vaccine efficacy.
The study, led by researchers at Massachusetts General Hospital (MGH), Harvard and MIT, tested blood from people who received the Moderna, Johnson & Johnson and Pfizer / BioNTech vaccines against a pseudovirus designed to resemble the Omicron variant.
They included individuals who had both been recently vaccinated or had recently taken booster doses and who also had previous SARS-CoV-2 infection.
The results, published on preprint Memedrxiv, meaning that they have not been peer-reviewed yet, showed that the neutralization of Omicron was ‘undetectable’ in most vaccinated individuals.
The study shows that Omicron drastically escapes vaccine-induced immunity after primary vaccination series with mRNA-1273 (Moderna), BNT162b2 (PfizerBioNTech) or Ad26.COV2.S (Johnson & Johnson / Janssen) and shows increased infectivity in vitro, increasing the potential for increased transmissibility, said Wilfredo F. Garcia-Beltran, Department of Pathology, MGH in Boston.
However, individuals boosted with mRNA vaccines showed potent neutralization of Omicron only 4-6 times lower than wild-type, suggesting that boosters increase the cross-reactivity of neutralizing antibody responses.
The team also found that Omicron pseudovirus is more contagious than any other tested variant. Overall, this study highlights the importance of boosters in expanding neutralizing antibody responses to highly divergent SARS-CoV-2 variants.
The study further showed that recipients of mRNA boosters after J&J vaccine showed markedly improved neutralizing titers, but did not achieve the breadth of response seen with mRNA primary vaccination followed by mRNA booster.
Our results suggest that these recipients of J&J vaccines may benefit from additional mRNA vaccine doses with the potential to further raise titers and expand their neutralizing activity, the researchers said.
Omicron breakthrough infections can result in impaired disease in vaccinated humans due to cellular and innate immunity, they noted.
These findings support the need for rapid and synchronized widespread implementation of mRNA boosters as a public health measure to limit the emergence and spread of highly mutated SARS-CoV-2 variants, Garcia-Beltran said.
The results are in line with other studies recently published by researchers at the University of Oxford, who said they found that the two-dose Pfizer and AstraZeneca Covid-19 vaccine regimens do not induce enough neutralizing antibodies to the new variant. (IANS / 4 hours ago) https://www.newkerala.com/us-news.php