3 COVID vaccine doses appear to protect against Omicron subvariants


Three new research report on COVID-19 vaccine effectiveness (VE) and antibody responses to Omicron, with one from Sweden discovering a drop in two-dose VE in opposition to extreme illness after the transition from the BA.1 to the BA.2 subvariant however three-dose safety remaining above 80% in opposition to extreme illness.

Additionally, a research from Hong Kong exhibits good antibody response in opposition to BA.2 after three doses, and one from the USA finds that nursing residence sufferers who obtained a 3rd dose had a 47% decrease danger of Omicron an infection.

Three-dose vaccine efficacy above 80%

A crew led by a Skane College Hospital researcher performed a vaccine-registry COVID-19 surveillance study of all 1,384,531 residents of a county in southern Sweden from Dec 27, 2020, when the COVID-19 vaccine rollout started in that nation, to Mar 15, 2022. The findings had been printed yesterday in Eurosurveillance.

Most doses (77%) had been of the Pfizer/BioNTech COVID-19 vaccine, with Moderna and AstraZeneca/Oxford making up the remaining doses.

The research spanned three intervals: week 52 of 2021 to week 1 of 2022, by which Omicron BA.1 was dominant (60% vs 25% Delta and 15% BA.2); weeks 2 and three of 2022, the transition interval (BA.1 [47%], Delta [4.5%], and BA.2 [49%]); and weeks 4 to 11 of 2022, when BA.2 was dominant (82% vs 17% BA.1 and 0.5% Delta).

A complete of 593 extreme COVID-19 infections occurred, similar to 65, 78, and 56 instances every week throughout BA.1 dominance, the transition interval, and BA.2, respectively. Relative to the BA.1 interval, in the course of the BA.2 interval, sufferers with extreme sickness had been older and had a extra even intercourse distribution. The overrepresentation of sufferers born outdoors of Sweden throughout BA.1 lessened throughout BA.2, however these sufferers had an analogous prevalence of persistent situations.

Estimated VE of two doses in opposition to extreme COVID-19 was 89% from March to November 2021, earlier than follow-up started. Inhabitants-level safety remained excessive throughout Delta and BA.1 dominance in December 2021, whereas VE declined in the course of the transition to BA.2 in January and February 2022.

After a minimum of three doses, VE in opposition to extreme illness remained above 80% all through the research interval however fell from 90% throughout BA.1 to 54% throughout BA.2 in two-dose recipients, no matter age, intercourse, and persistent situations.

Earlier SARS-CoV-2 an infection supplied comparable safety in opposition to reinfection after two or three vaccine doses throughout BA.1 and the transition interval, however the safety conferred by an infection and at most two doses dropped throughout BA.2, whereas the safety in opposition to extreme sickness conferred by least three doses remained excessive.

The important thing discovering, the researchers mentioned, was the steep decline in estimated VE in opposition to extreme COVID-19 throughout BA.2 dominance in two-dose vaccine recipients.

“The decline occurred fairly quickly over two months and thus can’t be defined by waning VE alone,” they wrote. “A extra probably rationalization is elevated immune evasiveness properties of BA.2, which supplies this genetically distinct subvariant a aggressive benefit in extremely vaccinated populations.”

“The comparatively steady safety amongst people with a minimum of three doses throughout follow-up in our research suggests {that a} very strong immune response is important to confer safety additionally in opposition to BA.2,” the researchers added. “These findings from our population-based research recommend that booster vaccination is required to keep up adequate safety in opposition to extreme COVID-19.”

Decrease antibody responses in unvaccinated BA.2 sufferers

A second study printed in Eurosurveillance, led by College of Hong Kong researchers, concerned a randomly chosen subset of 20 contributors from a earlier research evaluating ranges of plaque discount neutralization check (PRNT) antibodies in opposition to the wild-type and BA.1 SARS-CoV-2 variants. The research spanned Feb 21, 2020, to Nov 20, 2021.

Individuals included those that had been by no means contaminated with COVID-19 and had been vaccinated with three doses of the Pfizer or CoronaVac vaccine, in addition to those that obtained two doses of CoronaVac and one dose of Pfizer.

Unvaccinated contributors contaminated with the wild-type virus 143 to 196 days earlier had waning antibody concentrations in restoration. Serum was collected 3 to five weeks after the final dose of vaccine.

The researchers additionally collected and sequenced serum samples from survivors of BA.1 infections (14 sufferers) and presumed BA.2 (27) infections that occurred after Jan 21, 2022, when BA.2 was dominant. All BA.1-infected contributors and 20 contaminated with BA.2 had been reinfected.  Among the many 34 reinfected sufferers, 22 had been vaccinated with Pfizer, whereas 9 had obtained CoronaVac, and 1 every had obtained AstraZeneca, Moderna, and a mix of Pfizer and Johnson & Johnson (J&J).

Three doses of the Pfizer COVID-19 vaccine appeared to elicit better PRNT antibody response in opposition to BA.1 than three doses of CoronaVac. In each vaccinated contributors and people identified as having COVID-19 wild-type an infection with or with out vaccination, PRNT antibody responses to BA.2 had been considerably decrease than these in opposition to the wild-type virus, however PRNT antibody responses to BA.1 and BA.2 had been related. BA.2 infections in unvaccinated contributors resulted in low PRNT antibody ranges in opposition to BA.2, which had been 2- to 16-fold increased than these to BA.1. 

The research authors famous that there isn’t any universally accepted correlate of safety in opposition to COVID-19. “A single dose of both vaccine in these with earlier SARS-CoV-2 an infection elicited increased PRNT antibody responses than even three doses of the respective vaccine in an infection naïve people,” they wrote. “Breakthrough BA.1 or BA.2 an infection in beforehand vaccinated people appeared to offer broad cross-neutralisation in opposition to a spread of SARS-CoV-2 variants of concern.”

“In distinction, BA.2 an infection in non-vaccinated people offered low PRNT antibody responses to BA.2 with minimal breadth of cross-neutralisation they usually could also be vulnerable to an infection with BA.1 or different variants,” the researchers added.

Extra doses in nursing houses

Within the third study, printed immediately in Morbidity and Mortality Weekly Report, US Facilities for Illness Management and Prevention (CDC) researchers analyzed COVID-19 surveillance and vaccination knowledge from about 15,000 nursing residence residents from Feb 14 to Mar 27, 2022, a interval of widespread Omicron circulation.

Major vaccination was thought-about receipt of two doses of an mRNA vaccine, a single dose of J&J, or a further or booster dose a minimum of 14 days earlier than a optimistic COVID-19 check outcome. Individuals who had obtained just one or no doses had been thought-about unvaccinated.

A complete of 15,090 nursing houses reported 89,671 infections every week from Feb 14 to Mar 27, 2022, and 15,102 services reported 89,969 weekly resident counts from Jan 31 to March 13, 2022. The evaluation included 85,494 studies from 14,758 nursing houses.

The median weekly variety of residents reported was 1,126,198, roughly 22% of whom had obtained major vaccine doses solely and 65% of whom obtained a further or booster dose. Over 90% obtained mRNA COVID-19 vaccines.

A further major or booster dose of COVID-19 vaccine conferred better estimated safety (relative adjusted VE, 46.9%; 95% confidence interval [CI], 44.8% to 48.9%) in opposition to COVID-19 an infection, no matter week or nursing residence traits.

General, 7,510 infections had been reported amongst 1,509,674 resident-weeks with major collection vaccination solely and 11,334 infections had been recorded amongst 4,416,401 resident-weeks after a further or booster dose.

Weekly COVID-19 instances decreased in all vaccination teams in the course of the research interval, however charges amongst residents with a further or booster dose had been persistently decrease than these among the many unvaccinated and people who obtained the first collection vaccination solely.

“All immunocompromised nursing residence residents ought to obtain a further major dose, and all nursing residence residents ought to obtain a booster dose, when eligible, to guard in opposition to COVID-19,” the researchers wrote.

“Efforts to maintain nursing residence residents updated with vaccination ought to be carried out at the side of different COVID-19 prevention methods, together with testing and vaccination of nursing residence employees members and guests.”

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