FALSE.
Covid vaccines are moderately effective at preventing transmission from infected vaccinated individuals, especially with Alpha variant, although this effectiveness has declined with subsequent variants and also declines over time since vaccination.
Also, since Covid vaccines are effective at preventing infection, and you can't transmit if you're not infected, Covid vaccines can have a substantial impact on spread.
Also, since Covid vaccines effectively reduce the duration of infection, this contributes further to the reduction of transmission/spread.
The transmission endpoint (VET) refers to the likelihood that an infected vaccinated person will infect another contact (secondary attack rate or SAR) compared to the likelihood that an infected unvaccinated person will infect another contact.
Background: Janine Small, Pfizer's president of international developed markets testified before the European Parliament's COVID-19 committee on October 10, 2022, where she confirmed that Pfizer did not test whether the vaccine prevented transmission before it went on the market.
Transmission is never tested in a randomized control trial.
Pfizer never claimed they tested transmission.
The FDA press release announcing EUA on 2020-12-11 specifically stated "data are not available to make a determination about how long the vaccine will provide protection, nor is there evidence that the vaccine prevents transmission of SARS-CoV-2 from person to person."
https://www.fda.gov/news-events/press-announcements/fda-takes-key-action-fight-against-covid-19-issuing-emergency-use-authorization-first-covid-19 (2020-12-11)
"Vaccination and prior infection were each associated with similar reductions in infectiousness during SARS-CoV-2 infection, and, notably, additional doses of vaccination (for example, booster doses) against SARS-CoV-2 and more recent vaccination led to greater reductions in infectiousness."
https://www.nature.com/articles/s41591-022-02138-x (2023-01-02)
"Fully vaccinated individuals had a shorter duration of viable viral shedding and a lower rate of secondary transmission than partially vaccinated or unvaccinated individuals."
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2792598 (2022-05-24)
"VET [vaccine effectiveness against transmission of infection]-estimates were higher for mRNA-vaccines, over 90%, compared to viral vector vaccines: 66% and 80% for Ad26COV2.S and ChAdOx1 respectively (Alpha, 0-50 days after vaccination). Delta was associated with a 40% increase in odds of transmission and a decrease of VEs (72-64%) and especially of VEi (71-46% for BNT162b2)... Waning further reduced VET-estimates: from 81% to 63% for BNT162b2 (Delta, 150-200 days after vaccination)."
https://www.sciencedirect.com/science/article/pii/S0264410X22004418?via%3Dihub (2022-05-11)
PubMed: https://pubmed.ncbi.nlm.nih.gov/35459558/ (2022-05-11)
"Full vaccination reduced susceptibility and infectiousness, but more so for Alpha than Delta and Omicron. These findings suggest vaccination for SARS-CoV-2 transcends protection of the individual by conferring indirect protection to other household members, but the degree of protection is seemingly lower for emerging variants."
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2791601 (2022-04-28)
"We found that having a single vaccinated parent was associated with a 26.0 and a 20.8% decreased risk in the early and late periods, respectively, and having two vaccinated parents was associated with a 71.7 and a 58.1% decreased risk, respectively. Thus, parental vaccination confers substantial protection on unvaccinated children in the household."
https://www.science.org/doi/10.1126/science.abm3087 (2022-01-27)
"The secondary attack rate among household contacts was lower for fully vaccinated than unvaccinated index cases (11% vs 31%), with an adjusted VET of 71% (95% confidence interval: 63-77)."
https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2021.26.31.2100640#html_fulltext (2021-08)
PubMed: https://pubmed.ncbi.nlm.nih.gov/34355689/ (2021-08)
"Vaccination reduced susceptibility to infection by 89.4% [95% confidence interval (CI): 88.7 to 90.0%], whereas vaccine effectiveness against infectiousness given infection was 23.0% (95% CI: −11.3 to 46.7%) during days 10 to 90 after the second dose, before 1 June 2021."
https://www.science.org/doi/10.1126/science.abl4292 (2022-01-27)
"Effectiveness of full vaccination of the index case against transmission to unvaccinated and fully vaccinated household contacts, respectively, was 63% (95% confidence interval (CI): 46-75) and 40% (95% CI: 20-54), in addition to the direct protection of vaccination of contacts against infection."
https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2021.26.44.2100977 (2021-11)
PubMed: https://pubmed.ncbi.nlm.nih.gov/34738514/ (2021-11)
"Full-schedule vaccination was associated with significant protection against infection. In addition, mRNA-vaccines reduced onward transmission: VE-estimates increased to >90% when index and contact were fully vaccinated."
https://www.sciencedirect.com/science/article/pii/S0264410X21011087?via%3Dihub (2021-09-15)
PubMed: https://pubmed.ncbi.nlm.nih.gov/34454789/ (2021-09-15)
Effect of Covid-19 Vaccination on Transmission of Alpha and Delta Variants
https://www.nejm.org/doi/full/10.1056/nejmoa2116597 (2022-02-24)
"...we estimated that any vaccination, prior infection alone, and both vaccination and prior infection reduced an index case’s risk of transmitting to close contacts by 24% (9-37%), 21% (4-36%) and 41% (23-54%), respectively. Receipt of booster doses and more recent vaccination further reduced infectiousness among vaccinated cases."
https://www.medrxiv.org/content/10.1101/2022.08.08.22278547v2 (2022-08-31)
"Receipt of 2 or 3 mRNA vaccine doses before Delta infections and 3 mRNA vaccine doses before Omicron infections was significantly associated with milder COVID-19 (less frequently symptomatic, febrile, or medically attended or shorter duration of illness) compared with being unvaccinated."
https://jamanetwork.com/journals/jama/fullarticle/2797418 (2022-10-18)
"Fully vaccinated individuals had a shorter duration of viable viral shedding and a lower rate of secondary transmission than partially vaccinated or unvaccinated individuals."
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2792598 (2022-05-24)
"We report that the probability of infection post-vaccination is… associated with a significantly shorter median duration of infection than that of first infection and reinfection"
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0263014 (2022-01-31)
"Vaccination is associated with faster decline in viral RNA load and a robust serological response."
https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(21)00638-8/fulltext (2021-11-22)
"A faster decline was seen in the alpha (pp=0·93), unvaccinated delta (pp=0·79), and fully vaccinated delta (pp=0·99) groups than in the pre-alpha group. The mean viral load decline rate of the fully vaccinated delta group was also faster than those of the alpha group (pp=0·84) and the unvaccinated delta group (pp=0·85). The differences in decline rates translate into a difference of about 3 days in the mean duration of the decline phase between the pre-alpha and delta vaccinated groups."
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00648-4/fulltext (2021-10-29)
"Among participants with SARS-CoV-2 infection, the mean viral RNA load was 40% lower (95% CI, 16 to 57) in partially or fully vaccinated participants than in unvaccinated participants. In addition, the risk of febrile symptoms was 58% lower (relative risk, 0.42; 95% CI, 0.18 to 0.98) and the duration of illness was shorter, with 2.3 fewer days spent sick in bed (95% CI, 0.8 to 3.7)."
https://www.nejm.org/doi/10.1056/NEJMoa2107058 (2021-07-22)
"Receipt of 2 mRNA vaccine doses 14 to 149 days prior to either Delta or Omicron infection was significantly associated with lower viral RNA load."
https://jamanetwork.com/journals/jama/fullarticle/2797418 (2022-10-18)
"Full vaccination (defined as >2 weeks after receipt of the second dose during the primary vaccination series) significantly reduced infectious VL for Delta breakthrough cases compared to unvaccinated individuals. For Omicron BA.1 breakthrough cases, reduced infectious VL was observed only in boosted but not in fully vaccinated individuals compared to unvaccinated individuals. Our findings indicate that vaccines may lower transmission risk and, therefore, have a public health benefit beyond the individual protection from severe disease."
https://www.nature.com/articles/s41591-022-01816-0 (2022-04-08)
PubMed: https://pubmed.ncbi.nlm.nih.gov/35395151/ (2022-04-08)
"Among participants with SARS-CoV-2 infection, the mean viral RNA load was 40% lower (95% CI, 16 to 57) in partially or fully vaccinated participants than in unvaccinated participants."
https://www.nejm.org/doi/10.1056/NEJMoa2107058 (2021-07-22)
This study has significant weaknesses. Read the section "Discussion"
https://www.cdc.gov/mmwr/volumes/70/wr/mm7031e2.htm?s_cid=mm7031e2_w (2021-08-06)