Does a Delta-vaccine prevent transmission of Omicron? March 2022
How well does the vaccine intended for 2021 deltavariant prevent the transmission of the SARS-CoV-2 variants prevalent in spring 2022? Let's have a look at the available evidence.
I'm focusing on vaccine products available in Finland, but many of the articles do have a broader significance.
Which vaccine products are currently administered?
On this date koronarokotusaika.fi mentions Pfizer-Comirnaty, Moderna Spikevax, plus Janssen or Novavax on request: "Uudellamaalla yli 12-vuotiaille 1. ja 2. rokotuksissa on käytössä BioNTech-Pfizerin rokote kauppanimeltään Comirnaty, naisille ja tytöille sekä yli 30-vuotiaille miehille Modernan rokote kauppanimeltään Spikevax. Myös Janssenin ja Novavaxin rokotetta voidaan käyttää erikseen harkitusti." https://www.koronarokotusaika.fi/tietoa-koronarokotuksista/
Comirnaty, aka BNT162b2 https://laakeinfo.fi/Medicine.aspx?m=29864&d=83541381&i=PFIZER_COMIRNATY_COMIRNATY+injektiokonsentraatti%2C+dispersiota+varten+30+mikrog%2Fannos
Some reports from 2021
Pharmaceutical industry news mentioned in June 2021 that the Comirnaty (a delta-variant spike vaccine I believe) works in vitro on alpha, beta, gamma, and others. https://www.europeanpharmaceuticalreview.com/news/156472/comirnaty-covid-19-vaccine-protects-against-multiple-viral-variants/
Omicron variant in November 2021 news https://www.nature.com/articles/d41586-021-03552-w
Nature News reported that Omicron variants are likely to weaken protection in December 2021 https://www.nature.com/articles/d41586-021-03672-3
Pfizers December 2021 press release on variant efficacy https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-provide-update-omicron-variant
Netherlands virus researchers report a different cell type affinity for Omicron in contrast to Delta in January 2022, implying that Omicron variants may no longer effect lung epithelium. https://www.biorxiv.org/content/10.1101/2022.01.19.476898v1.full.pdf
Which variants are currently prevalent?
WHO Interim Statement in March 2022 reported of "dominance of Omicron variant in all six WHO regions." They also report that all the current vaccines are based on an early variant. https://www.who.int/news/item/08-03-2022-interim-statement-on-covid-19-vaccines-in-the-context-of-the-circulation-of-the-omicron-sars-cov-2-variant-from-the-who-technical-advisory-group-on-covid-19-vaccine-composition-(tag-co-vac)-08-march-2022
Euronews reports that "while BA.1 has dominated case numbers around the world, it causes less severe disease compared to the delta variant" and that "BA.2 may pose a similar risk of hospitalization as BA.1." https://www.euronews.com/next/2022/03/30/stealth-omicron-is-subvariant-ba-2-a-more-transmissable-strain-of-covid-and-should-we-be-w
Public Health Ontario report on Omicron March 2022 https://www.publichealthontario.ca/-/media/Documents/nCoV/voc/2022/03/omicron-variant-ba2-risk-assessment-mar-8.pdf?sc_lang=en
What is the effectiveness of the available vaccine products on the prevalent variants?
Nature News reported in February 2022 that a fourth vaccine dose improves antibody response but offers limited protection from infection. They report that antibodies do block Omicron but not as well as Delta. https://www.nature.com/articles/d41586-022-00486-9
WHO made and Interim Statement on vaccines in context of Omicron in March 2022 https://www.who.int/news/item/08-03-2022-interim-statement-on-covid-19-vaccines-in-the-context-of-the-circulation-of-the-omicron-sars-cov-2-variant-from-the-who-technical-advisory-group-on-covid-19-vaccine-composition-(tag-co-vac)-08-march-2022
Nature News reported in March 2022 about vaning antibody responses in 6 months https://www.nature.com/articles/d41586-022-00885-y
Israeli researchers report in NEJM Correspondence letter: "Vaccine efficacy was estimated to be higher for the prevention of symptomatic disease (43% for BNT162b2 and 31% for mRNA-1273)" https://www.nejm.org/doi/full/10.1056/NEJMc2202542
Nature News reported in March 2022: Protection against BA.2 did not seem to wane any faster than protection against BA.1, and a booster shot brought the protection against symptomatic infection by either subvariant back to 30–60%. Surveillance data collected in the United Kingdom reveal a similar trend: vaccine effectiveness against symptomatic COVID-19 is less than 20% for both subvariants 25 weeks or more after a second dose, but rises to roughly 70% 2–4 weeks after a third dose ... protection against severe disease remained at 68% or higher for at least 7 months - https://www.nature.com/articles/d41586-022-00775-3
Effect of vaccine-products on transmission of Omicron variants is unknown
Within the time limits no evidence on the effect of vaccines on transmission of SARS-CoV-2 Omicron variants BA.1 or BA.2 was found. That is, in my review of the medical publications available, using Pubmed, Google and Nature publications searches. Such information may exists behind a paywall, but was not found in my searches or queries.
So, seems the effect on transmission is not studied.
Studies focus on the prevention of severe forms of disease, i.e. the COVID-19 disease. There the preventative effect of mRNA vaccine-series (2-3) was quantified to be between 31% and 70% for several months following the vaccine-series, diminishing by 6th month.
Copyright Casimir Pohjanraito 2021