Table 1.
Summary of included studies on heterologous COVID-19 vaccination.
| Author | Country | Study design | Vaccine regimens† | Time period after boosting | Mean of age (range of age) | Gender Female (%) | Vaccine regimen | Sample size |
|---|---|---|---|---|---|---|---|---|
| Borobia[22] | Spain | Open label, randomized controlled trial | ChAd/BNT ChAd/no boost | 14 days | 43.98 (18–60 years) | 56.5% | ChAd, BNT | 676 |
| Liu[28] | UK | Single-blind, randomized non-inferiority trial | ChAd/BNT ChAd/ChAd | 28 days | 57.8 (≥50 years) | 45.8% | ChAd, BNT | 830 |
| Shaw[18] | UK | Multi-center, single-blind, randomized non-inferiority trial | ChAd/ BNTBNT/BNTBNT/ChAdChAd/ChAd | 28 days | 57.8 (≥50 years) | 45.8% | ChAd, BNT | 830 |
| Li[26] | China | Randomized, controlled, observer-blinded trial | CoVac/ConvideciaCoVac/CoVac | 28 days | 44.25 | 41% | 299 | |
| Tenbusch[19] | Germany | Non-blinded non-randomized study | ChAd/ChAdChAd/BNTBNT/BNT | 2 weeks | 42.5 (31–55) | 90.2% | ChAd, BNT | 642 |
| Hillus[23] | Germany | Prospective cohort study | ChAd/ChAdChAd/BNTBNT/BNT | 3 weeks | 35 | 66.6% | ChAd, BNT | 380 |
| Groβ[24] | Germany | Prospective cohort study | ChAd/BNT | 14–19 days | 30.5 (25–46 yrs) | 61.5% | ChAd, BNT | 26 |
| Barros[30] | Germany | Prospective cohort study | ChAd/ChAdChAd/BNTBNT/BNT | 17 days | 39 | 75% | ChAd, BNT | 129 |
| Behrens[31] | Germany | Prospective cohort study | ChAd/ChAdChAd/BNT | 16.3 days | 39 | 21.7 | ChAd, BNT | 23 |
| Benning[32] | Germany | Prospective cohort study | ChAd/ChAdChAd/BNTBNT/BNT | 20 days | ChAd/ChAd 55 (33–60 yrs)ChAd/BNT 30 (24–45 yrs)BNT/BNT 45 (33–56 yrs) | 81% | ChAd, BNT | 134 |
| Dimeglio[34] | France | Prospective cohort study | ChAd/ChAdChAd/BNTBNT/BNT | 28 days | 37 (20–55 yrs) | 74% | ChAd, BNT | 132 |
| Fabricius[35] | Germany | Prospective cohort study | BNT/BNTmRNA1273/mRNA1273ChAd/BNTCHAd/mRNA1273ChAd/ChAd | 2 weeks | 44 | 62% | ChAd, mRNA 1273 | 116 |
| Hammerschmidt[20] | Germany | Prospective cohort study | ChAd/ChAdChAd/BNTBNT/BNT | 17 days | NA | 75% | ChAd, BNT | 115 |
| Kant[25] | India | Retrospective cohort study | ChAd/CovaxinChAd/ChAdCovaxin/Covaxin | 3 weeks | ≥ 50 yrs | 49% | ChAd, Covaxin | 98 |
| Normark[29] | Sweden | Prospective cohort study | ChAd/ChAdChAd/mRNA1273 | 30 days | 43 (23–62 yrs) | NA | ChAd, mRNA1273 | 88 |
| Schmidt[33] | UK | Prospective cohort study | ChAd/ChAdChAd/mRNA1273mRNA1273/mRNA1273 | 13 days | 47.1 | 69.9% | ChAd, mRNA1273 | 213 |
| Valiee[21] | France | Prospective cohort study | ChAd/BNTBNT/BNT | 30 days | 34.5 | 69.1% | ChAd, BNT | 197 |
| Yorsaeng[36] | Thailand | Prospective cohort study | CoVac/CoVacCoVac/ChAdChAd/ChAd | 32 days | 41.5 | 62.7% | ChAd, Covac | 214 |
| Schmidt[27] | Prospective cohort study | ChAd/ChAdChAd/mRNA1273mRNA1273/mRNA1273 | 14 days | 54.5 | 65.5% | ChAd, mRNA1273 | 110 |
†Bold text indicates the heterologous regimens.
mRNA: messenger RNA; mRNA1273: Vaccine from Moderna company; ChAd: Astrazeneca, vector (Covisheld) vaccine; BNT: Pfizer mRNA vaccine; Convidecia: recombinant adenovirus type-5-vectored vaccine; CoronaVac: inactivated SARS-CoV-2 vaccine (CoVac); Covaxin: inactivated whole virion BBV152 vaccine; NA: not available;