Table 2.
Characteristics of the included studies
| First Author, Published Year | Moa, 2016 | Meng, 2018 | Huang, 2020 | Liang, 2021 | Minozzi, 2022 |
|---|---|---|---|---|---|
| Type of study | Systematic review | Systematic review | Systematic review | Systematic review | Systematic review and NMA |
| Country of primary studies | Australia, United States, Czech Republic, Germany, Romania, Spain, Korea, Taiwan, France, Canada and Mexico | China, United States, Czech Republic, Germany, Romania, Spain, Korea, Taiwan, France, Canada, Mexico, China, Belgium and Poland | China, United States, Canada, Dominican Republic, Honduras, Asia, Latin America, Europe, South Korea, China, Czech Republic, France, Germany, Philippines, Mexico, Spain, Taiwan, Poland, Finland | China, United States, Czech Republic, Germany, Romania, Spain, Korea, Taiwan, France, Canada, Mexico, China, Belgium and Poland | Continental Europe, Africa, Asia, North America, South America, Oceania, Multi-continent |
| Study period | 6/30/2015 | Not informed | 2/12/2019 | 2011–2020 | 12/15/2020 |
| Search strategy | Not informed | Not informed | (quadrivalent OR tetravalent) AND (influenza OR flu) AND vaccine | QIV and TIV |
#1 “Influenza, Human”[MeSH] #2 “Influenzavirus A”[MeSH] #3 “Influenzavirus B”[MeSH] #4 influenza*[Text Word] OR flu[Text Word] #5 #1 OR #2 OR #3 OR #4 #6 “Vaccines”[MeSH] #7 “Immunization”[MeSH] #8 (vaccin*[Text Word] OR immuni*[Text Word] OR inocula*[Text Word]) #9 #6 OR #7 OR #8 #10 #5 AND #9 #11 “Influenza Vaccines”[MeSH] #12 #10 OR #11 #13 “Randomized Controlled Trial” [Publication Type] #14 “Controlled Clinical Trial” [Publication Type] #15 randomized[Title/Abstract] #16 placebo[Title/Abstract] #17 “drug therapy” [Subheading] #18 randomly[Title/Abstract] #19 trial[Title/Abstract] #20 groups[Title/Abstract] #21 #13 OR #14 OR #15 OR #16 OR #17 OR #18 OR #19 OR #20 #22 (“Animals”[MeSH]) NOT “Humans”[MeSH] #23 #21 NOT #22 #24 #12 AND #23 |
| Searched databases | Medline, EMBASE, Cochrane Central Register of Controlled Trials, Scopus and Web of Science | Medline, Cochrane Library, Science Direct | PubMed, EMBASE and Cochrane Library | Cochrane Library, PubMed, ClinicalTrials.gov, EMBASE, China Biology Medicine disc, Chinese National Knowledge Infrastructure, and Wanfang Data. | Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (PubMed) and EMBASE |
| Number of included studies, and phase | 5 RCT (1 phase I/II, 1 phase II and 3 phase III) | 8 RCT (1 not informed, 1 phase I/II, 1 phase II and 5 phase III) | 9 RCT (3 phase II and 6 phase III) | 9 RCT (1 not informed, 1 phase I/II, 1 phase II and 6 phase III) | 220 RCT (phase not informed) |
| Population | Adults aged > 18 years | Adults between 18 to 64 years of age | Healthy children and adolescents aged from 6 months to 18 years | Adults between 18 to 64 years of age | Healthy children (< 18 years), healthy adults (18 − 60 years), and the elderly (age ≥ 61 years) |
| Total number of participants | 8,934 | 15,123 | 14,819 | 16,422 | 429,804 |
| Intervention | QIV vaccine, 15 μg haemagglutinins per strain, and were given as 0.5 mL dose intramuscularly. | Quadrivalent inactivated influenza vaccine (QIV) | QIV contained 15 μg each of the A/H1N1, A/H3N2, B/Victoria and B/Yamagata | Quadrivalent inactivated influenza vaccine (QIV) | Trivalent and quadrivalent inactivated influenza vaccines (IIVs) (whole virus, split or sub-unit) administered intramuscularly (IM) or intradermically (ID), live-attenuated influenza vaccines (LAIVs) administered by intranasal (IN) route, recombinant influenza vaccines (RIVs) administered IM. |
| Comparator | TIV vaccines, 15 μg haemagglutinins per strain, and were given as 0.5 mL dose intramuscularly. | Trivalent inactivated influenza vaccine (TIV) | TIV contained 15 μg each of the A/H1N1 and A/H3N2 and 15 μg of the B/Victoria or B/Yamagata | Trivalent inactivated influenza vaccine (TIV) | Trivalent and quadrivalent inactivated influenza vaccines (IIVs) (whole virus, split or sub-unit) administered intramuscularly (IM) or intradermically (ID), live-attenuated influenza vaccines (LAIVs) administered by intranasal (IN) route, recombinant influenza vaccines (RIVs) administered IM. |
| Quality assessment | ROB 1.0 | ROB 1.0 | ROB 1.0 | ROB 1.0 | ROB 1.0 |
| Funding sources | Not informed | Not informed | National Natural Science Foundation of China and Mega-Project of National Science and Technology for the 12th and 13th Five-Year Plan of China | Medical Science and Technology Innovation Project of Chinese Academy of Medical Sciences, Medical Science and Technology Innovation Project of Chinese Academy of Medical Sciences and Innovation Team in Yunnan Province | Directorate general of welfare, Lombardy region. |
| Conflicts of interest | From one author that contributed to the study design, statistical analysis, and editing of manuscript. | No potential conflicts of interest were disclosed. | No potential conflicts of interest were disclosed. | No potential conflicts of interest were disclosed. | One author declares support for attending meeting and travel by Sanofi and Seqirus and, participation in Advisory Board of Sanofi. One author declares participation in Advisory Board of Sanofi. |
RCT: Randomized Controlled Trial; ROB: Cochrane’s risk of bias; NMA: Network metanalysis.