Evidence about public-health measures

Below we provide the ‘best’ living evidence syntheses currently available (i.e., the highest quality, most regularly updated living evidence syntheses) about COVID-19 public-health measures. All other evidence syntheses can be found in the searchable COVID-END inventory of evidence syntheses, which is organized using the COVID-END taxonomy of decisions.

Topic addressedCriteria for 'best evidence synthesis' Details to support relevance assessment Additional decision-relevant details Citation
Date of last search Quality (AMSTAR) rating Evidence-certainty (e.g., GRADE) assessment available             Key findings
Living evidence synthesisType of synthesis             Type of question
Effectiveness of vaccines in adults,  children and over longer time horizons2022-04-277/9NoRather than provide a high-level summary of the key findings from this complex synthesis, we encourage readers to look directly at the full review or to the rows in the second table belowYes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
 2022-01-315/9YesIn adolescents aged 12 to 15, one or two doses of the Pfizer vaccine may prevent infection, including against the Delta variant of concern; two doses of the Pfizer vaccine may also prevent ICU admissions and MIS-C from the Delta variant of concern Yes (row content last checked on 2022-04-25)Rapid reviewBenefits and harms
Flórez ID, Velásquez-Salazar P, Martínez JC, Linkins L, Abdelkader W, Iorio A, Lavis J, Patiño-Lugo DF. COVID-19 living
evidence synthesis #8 (version 2): What is the effectiveness of available COVID-19 vaccines in children and adolescents in general and
specifically for variants of concern? Evidence and Deliberation Unit for Decision Making (UNED), University of Antioquia & Health
Information Research Unit (HIRU), McMaster University, 04 January 2022.
Testing and seroprevalence2021-04-3010/11No

The diagnostic accuracy of antigen rapid diagnostic tests for COVID-19 has been estimated at 71.2% sensitivity and 98.9% specificity, and is particularly high when performed during the first week of illness, although a large number of studies did not perform the tests following manufacturers recommendations [Review of studies of variable quality and important heterogeneity among some of their findings]

See most updated version in this link: https://www.klinikum.uni-heidelberg.de/diagnostics-global-health

Yes (row content last checked on 2022-04-25)Full reviewTest accuracyBrümmer LE, Katzenschlager S, Gaeddert M, Erdmann C, Schmitz S, Bota M, et al. The accuracy of novel antigen rapid diagnostics for SARS-CoV-2: A living systematic review and meta-analysis. PLOS Medicine. 2021;18(8):e1003735.
 2022-04-108/11No

Estimates of the global seroprevalence of SARS-CoV-2 antibodies remain relatively low with important variations among geographical regions and specific populations [Review of studies of variable quality]

See the interactive map of the global seroprevalence here

Yes (row content last checked on 2022-04-25)Full reviewOtherBobrovitz N, Arora RK, Cao C, Boucher E, Liu M, Rahim H, et al. Global seroprevalence of SARS-CoV-2 antibodies: A systematic review and meta-analysis. medRxiv. 2021.
Masks and other PPE2021-07-026/9NoWhereas no research was found on the effectiveness of wearing masks in community settings for COVID-19, studies on SARS and influenza showed that the evidence for wearing masks is stronger in healthcare settings compared to community settings, whereas PPE use by healthcare workers has been found to be one of the strongest factors associated with reduced risk of coronavirus infectionYes (row content last checked on 2022-04-25)Rapid reviewBenefits and harmsChou R, Dana T, Jungbauer R. Update Alert 5: Masks for prevention of respiratory virus infections, including SARS-CoV-2, in health vare and community settings. Annals of Internal Medicine. 2021.
 2021-10-246/10NoUsing PPE was found to be the strongest factor associated with reducing risk of coronavirus infection among healthcare workers, while wearing two filtering facepiece masks was associated with a reduced risk of COVID-19 infection, when compared to a single surgical mask [Review of observational studies]Yes (row content last checked on 2022-04-25)Rapid reviewOtherChou R, Dana T, Buckley DI, Selph S, Fu R, Totten AM. Update alert 10: Epidemiology of and risk factors for coronavirus infection in health care workers. Annals of Internal Medicine. 2021.
Because the searchable COVID-END inventory is organized at the level of an evidence synthesis, we provide below an additional ‘way in’ to the evidence syntheses addressing vaccine effectiveness. Specifically, we summarize what’s known at the level of each individual vaccine (e.g., Pfizer/BioNtech/Comirnaty), drawing on the first evidence synthesis in the table above. 

Broad and specific decisions Criteria for 'best evidence synthesis' Details to support relevance assessment Additional decision-relevant details Citation
Date of last search Quality (AMSTAR) rating Evidence-certainty (e.g., GRADE) assessment availableKey findings
Living evidence synthesisType of synthesisType of question
Infection prevention         
 Vaccination
  Safety and efficacy of two doses of the same vaccine if two doses are recommended (or a single dose if a single dose is recommended)2022-04-277/9No[BioNTech/Pfizer against variants of concern] BNT162b2 [Pfizer] vaccine may prevent infection from the Omicron variant of concern up to 44 days and may provide limited protection up to 60 days after the second dose; it may also prevent symptomatic infection up to 63 days after the second dose, and may provide limited protection up to 90 days after the second dose (other variants are also included in the report) Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2021-10-0110/11Yes[BioNTech/Fosun Pharma/Pfizer vaccine (age-group analysis available)] Compared to placebo, vaccination with BNT162b2 reduces the incidence of symptomatic cases of COVID-19, and probably reduces severe and critical disease substantially, although there remains uncertainty about the effect on mortality; it may increase the incidence of severe adverse events [Note: this declarative title was written based on last posted summary of findings table]Yes (row content last checked on 2022-05-09)Full review Benefits and harms COVID NMA. Overall effectiveness and safety of all vaccines vs placebo. 2021.
   2021-07-127/11Yes[BioNTech/Pfizer] Vaccination with the Pfizer/BioNTech vaccine reduces the risk of contracting COVID-19 substantially even after the first dose and it probably reduces the risk of severe COVID-19, whereas its effects on other outcomes are yet to be determined; the incidence of serious adverse events may slightly increase, whereas the incidence of any adverse event substantially increaseYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Pfizer-BioNTech COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2021-07-128/11Yes[CanSino] No evidence from phase III randomized controlled trials has been reported to enable an assessment of the safety and efficacy of the CanSino vaccineYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. CanSino COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2021-12-1010/11Yes [Coronavac vaccine] Compared to placebo, vaccination with CoronaVac may reduce the incidence of symptomatic cases of COVID-19 by 50%, close to the lowest level deemed effective by the WHO and it may substantially reduce the incidence of severe disease due to COVID-19; the evidence for any difference in serious adverse events is uncertain, although the vaccination probably increases the incidence of any adverse eventYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsCOVID NMA. Coronavac vs placebo. 2021
   2021-07-126/11Yes[CoronaVac/Sinovac vaccine] Vaccination with the CoronaVac/Sinovac vaccine reduces the risk of contracting COVID-19 (even after the first dose) and it probably reduces the risk of severe COVID-19, whereas its effects on other outcomes are yet to be determined; the incidence of serious adverse events probably does not increase, whereas the incidence of any adverse event is higherYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Sinovac COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2022-04-277/9NoYes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.

   2021-07-126/9Yes[Covaxin] No evidence from phase III randomized controlled trials has been reported to enable an assessment of the safety and efficacy of the Covaxin vaccineYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Bharat Biotech COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2022-04-277/9No[Covaxin vaccine against variants of concern] Covaxin/BBV152 vaccine may provide protection against symptomatic infection due to the Delta variant of concern No studies have been found for the Omicron variant of concern
Yes (row content last checked on 2022-05-09)
Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2021-12-1010/11Yes[EpiVacCorona] The effects of vaccination with EpiVacCorona are uncertainYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsCOVID NMA. EPIVACCORONA VS PLACEBO. COVID NMA: Vaccines for COVID-19 patients. 2021.
   2021-07-126/9Yes[EpiVacCorona] No evidence from phase III randomized controlled trials has been reported to enable an assessment the safety and efficacy of the EpiVacCorona vaccineYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Vector Institute COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2021-12-1010/11Yes [Gamaleya Research Institute vaccine] Compared to placebo, vaccination with Gam-COVID-Vac rAd26-S/rAd5-S probably reduces the incidence of symptomatic and severe cases of COVID-19 substantially, although there remains uncertainty about the impact on reducing mortality; the vaccination may not increase the incidence of serious adverse event, but the incidence of any adverse event was not reportedYes (row content last checked on 2022-05-09)Full review Benefits and harms COVID NMA. Gam-COVID-Vac rAd26-S/rAd5-S vs Placebo (Gamaleya Research Institute of Epidemiology and Microbiology). 2020. 
   2021-07-126/11Yes[Gamaleya Research Institute vaccine] Vaccination with the Gamaleya vaccine probably reduces the risk of contracting COVID-19 substantially (even after the first dose) and it may reduce the risk of severe COVID-19, whereas its effects on other outcomes are yet to be determined; the incidence of serious adverse events may not be increasedYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Gamaleya COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2022-04-277/9No[Johnson & Johnson against variants of concern] Johnson & Johnson/AD26.COV2.S vaccine may provide limited protection from infection from the Omicron variant of concern up to 60 days after the second dose (other variants are also included in the report) Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2021-12-1010/11Yes [Johnson & Johnson's Janssen vaccine] Vaccination with AD26.COV2.S probably reduces the incidence of symptomatic cases of COVID-19 by around 67%, and it probably reduces severe disease and mortality, while the incidence of serious adverse events may not increaseYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsCOVID NMA. Ad26.COV2.S (5×10^10 vp) D0 vs Placebo. 2021.
   2021-07-126/11Yes[Janssen vaccine] Vaccination with the Janssen vaccine reduces the risk of contracting COVID-19 substantially and reduces the risk of severe COVID-19, whereas its effects on other outcomes are yet to be determined; the vaccination increases the incidence of serious adverse eventsYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Janssen COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2022-04-277/9No[Moderna against variants of concern] mRNA-1273 [Moderna] vaccine may provide limited protection for infection from the Omicron variant up to between 30 and 44 days, 60 and 90 days after the second dose, and it may prevent symptomatic infection from 14-149 days after the second dose (other variants are also included in the report) Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2021-12-1010/11Yes [ModernaTX vaccine (age-group analysis available)] Compared to placebo, vaccination with mRNA-1273 probably reduces the incidence of symptomatic cases of COVID-19 substantially, and it may reduce severe disease, while the incidence of serious adverse events is probably not increasedYes (row content last checked on 2022-05-09)Full review Benefits and harms COVID NMA. mRNA-1273 vs placebo (ModernaTX). 2020. 
   2021-07-126/11Yes[ModernaTX vaccine] Vaccination with the ModernaTX vaccine reduces the risk of contracting COVID-19 substantially (but it may reduce this risk with the first dose) and reduces the risk of severe COVID-19, whereas its effects on other outcomes are yet to be determined; the vaccination probably does not increase the incidence of serious adverse eventsYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Moderna COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2022-04-277/9No[Novavax against variants of concern] No studies have been identified evaluating Novavax/NVX-Co2373 vaccine against the Delta variant of concern No studies have been found for the Omicron variant of concern Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2021-12-1010/11Yes[Novavax vaccine] The effects of vaccination against COVID-19 with the Novavax vaccine are currently uncertain; it probably slightly increase the risk of any adverse eventsYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsCOVID NMA. NOVAVAX - NVX-COV2373 VS PLACEBO. COVID NMA: Vaccines for COVID-19 patients. 2021.
   2021-07-128/11Yes[Novavax] Vaccination with Novavax reduces the risk of contracting COVID-19 and probably reduces severe diseaseYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Novavax COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2022-04-277/9No[Oxford/AstraZeneca against variants of concern] ChAdOx1 [AstraZeneca] vaccine may prevent infection caused by the Omicron variant of concern at up to 60 days after the second dose (other variants are also included in the report) Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.

   2021-12-1010/11Yes [Oxford/AstraZeneca vaccine] Compared to vaccinating with MedACWY (meningitis vaccine), vaccination with ChAdOx1 probably reduces the cases of symptomatic SARS-CoV-2 infection, and may reduce severe or critical disease and hospitalisations; the effects on mortality are uncertain, and adverse events are probably less frequent.Yes (row content last checked on 2022-05-09)Full review Benefits and harms COVID NMA. ChAdOx1 vs MenACWY (University of Oxford/AstraZeneca ). 2020. 
   2021-07-126/11Yes[Oxford/AstraZeneca] Vaccination with the EU Nodes - Oxford/AstraZeneca vaccine reduces the risk of contracting COVID-19 and may reduce the risk of severe COVID-19, whereas its effects on other outcomes are yet to be determined; the vaccination probably does not increase the overall frequency of serious adverse eventsYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. EU Nodes-AstraZeneca/ Oxford; AstraZeneca/SK BIO; Serum Institute of India COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2021-12-1010/11Yes[Sinopharm - strain HBO2] Vaccination with Sinopharm HBO2 probably reduces the incidence of symptomatic cases of COVID-19, and it may reduce severe disease, while the incidence of adverse events is probably not increasedYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsCOVID NMA. SARS-COV-2 STRAIN HBO2 VS PLACEBO. COVID NMA: Vaccines for COVID-19 patients. 2021.
   2021-12-1010/11Yes[Sinopharm - strain WIV04] Vaccination with Sinopharm WIV04 probably reduces the incidence of symptomatic cases of COVID-19, and it may reduce severe disease, while the incidence of adverse events is probably not increasedYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsCOVID NMA. SARS-COV-2 STRAIN WIV04 VS PLACEBO. COVID NMA: Vaccines for COVID-19 patients. 2021.
   2021-07-126/9Yes[Sinopharm - WIBP] No evidence from phase III randomized controlled trials has been reported to enable and assessment of the safety and efficacy of the Sinopharm - WIBP vaccineYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Sinopharm/WIBP COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2021-07-126/9Yes[Zifivax] No evidence from phase III randomized controlled trials has been reported to enable an assessment of the safety and efficacy of the Zifivax vaccineYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsPan American Health Organization. Anhui Zhifei Longcom COVID-19 vaccine - Efficacy and effectiveness of the vaccine. Pan American Health Organization.; 2021.
   2021-02-088/11NoA review exploring factors influencing the efficacy of COVID-19 vaccines found that type of the vaccine technology (e.g., mRNA versus adenovirus), age, sex and the infection rate in the population did not influence vaccine efficacyNo Full reviewBenefits and harmsCalzetta L, Ritondo BL, Coppola A, Matera MG, Di Daniele N, Rogliani P. Factors influencing the efficacy of COVID-19 vaccines: A quantitative synthesis of phase III trials. Vaccines (Basel). 2021;9(4):341.
  Safety and efficacy of three doses if two doses were recommended before the emergence of variants2022-04-277/9Yes[BioNTech/Pfizer against variants of concern] Three doses of BNT162b2 [Pfizer] vaccine may prevent infection from the Omicron variant of concern up to 30 days after the third dose, it may prevent infection up to 60 days, and it may provide limited protection after 90 days of the third dose; it may also provide strong protection against severe, critical, or fatal disease produced by the Omicron variant of concern (other variants are also included in the report)Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms 
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2022-04-277/9Yes[BioNTech/Pfizer booster against variants of concern] 1 dose of BNT162b2 [Pfizer] vaccine as a booster of a completed 2 doses of ChadOx1 [AstraZeneca] probably prevent symptomatic infection from the Omicron variant of concern at 14 days after the last doseYes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms 
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2022-04-277/9Yes[BioNTech/Pfizer booster against variants of concern] One dose of BNT162b2 [Pfizer] vaccine as a booster of a completed two-dose course of CoronaVac [Sinovac] may prevent symptomatic infection and severe disease from the Omicron variant of concern eight to 59 days after the last doseYes (row content last checked on 2022-05-09)Rapid reviewBenefits and harmsIorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2022-04-277/9Yes[CoronaVac booster against variants of concern] Three doses of CoronaVac [Sinovac] vaccine may provide limited protection from symptomatic infection and it may prevent severe disease from the Omicron variant of concern after eight to 59 days after the last doseYes (row content last checked on 2022-05-09)Rapid reviewBenefits and harmsIorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2022-04-277/9Yes[Any mRNA vaccine as booster against variants of concern] 1 dose of a mRNA vaccine [Pfizer or Moderna] as a booster of a completed 2 doses of ChadOx1 [AstraZeneca] may prevent symptomatic infection from the Omicron variant of concern at 175 days after the last doseYes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms 
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2022-04-277/9Yes[Moderna against variants of concern] Three doses of Moderna vaccine may prevent infection from the Omicron variant of concern up to 30 days , and up to 60 days after the third dose, and it may prevent severe, critical, and fatal disease death up to 42 days after the third dose (other variants are also included in the report)Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
 
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
  Safety and efficacy of one dose of one vaccine and a second dose of a different vaccine (i.e., mix and match or heterologous prime and boost)2022-04-277/9No[BioNTech/Pfizer or Moderna to complete vaccination scheme started with Astra Zeneca against variants of concern] Vaccinating with Astra Zeneca followed by BioNTech/Pfizer or Moderna vaccine may prevent infection (including symptomatic infection) from the Delta variant of concern No studies have been found for the Omicron variant of concern Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
   2021-08-2710/11Yes[AstraZeneca to complete vaccination scheme started with BioNTech/Pfizer BNT16b2 at 28 days vs two doses of BioNTech/Pfizer BNT16b2 separated by 28 days] Compared to vaccination with two doses of the BNT16b2 vaccine, having a second dose of AstraZeneca after a first dose of BNT16b2 may increase the risk of any adverse event, while the incidence of serious adverse events is uncertainYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsBNT/CHA-28 VS BNT/BNT-28 COVID NMA; 2021.
   2021-08-2710/11Yes[BioNTech/Pfizer BNT162b2 to complete vaccination scheme started with AstraZeneca at 28 days vs two doses AstraZeneca separated by 28 days] Compared to vaccination with two doses of the AstraZeneca vaccine 28 days apart, having a second dose of BNT16b2 after a first dose of AstraZeneca may not increase the risk of any adverse event, while the incidence of serious adverse events is uncertainYes (row content last checked on 2022-05-09)Full reviewBenefits and harmsCHAD/BNT-28 VS CHAD/CHAD-28. COVID NMA; 2021.
   2022-04-277/9Yes[BioNTech/Pfizer BNT162b2] 3 doses of Pfizer/Comirnaty vaccine may prevent infection from the Omicron variant of concern up to 30 days after the third dose, while it may prevent symptomatic infection from the Omicron variant of concern up to 14 days after the third dose No studies have been found for the Omicron variant of concernYes (row content last checked on 2022-05-09)Rapid reviewBenefits and harms
Iorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.

   2022-04-277/9Yes[Johnson & Johnson against variants of concern] One dose of Johnson & Johnson/AD26.COV2.S vaccine followed by a second dose of an mRNA vaccine may prevent infection from the Omicron variant of concern at least 7 days after the second dose (other variants are also included in the report)Yes (row content last checked on 2022-05-09)Rapid reviewBenefits and harmsIorio A, Little J, Linkins L, Abdelkader W, Bennett D, Lavis JN. COVID-19 living evidence synthesis #6 (version 6.35): What is the efficacy and effectiveness of available COVID-19 vaccines in general and specifically for variants of concern? Hamilton: Health Information Research Unit;2022.
Drugs used as chemoprophylaxis for COVID-19 are addressed in the clinical management part of the COVID-END inventory of evidence syntheses, given their benefits accrue only at the individual level (not at the population level, as occurs with vaccinations through herd immunity).