Study characteristics
| Dataset 0: all studies | Dataset 1: low and moderate risk of bias studies | Dataset 2: low and moderate risk of bias studies; national scope | |
| Used in descriptive analysis | Used to estimate seroprevalence over time and identify associated factors | Used to estimate ascertainment | |
| Study characteristic | n=153* | n=97* | n=38* |
| World Bank income level | |||
| Low-income country | 96 (63) | 54 (56) | 24 (63) |
| Lower middle income country | 33 (22) | 22 (23) | 11 (29) |
| Upper middle income country | 24 (16) | 21 (22) | 3 (7.9) |
| High-income country | 0 (0) | 0 (0) | 0 (0) |
| Humanitarian response plan (HRP) | |||
| Vulnerable HRP country | 63 (41) | 51 (53) | 10 (26) |
| UN subregion | |||
| Eastern Africa | 103 (67) | 54 (56) | 26 (68) |
| Southern Africa | 22 (14) | 20 (21) | 2 (5.3) |
| Western Africa | 18 (12) | 17 (18) | 8 (21) |
| Middle Africa | 8 (5.2) | 6 (6.2) | 2 (5.3) |
| Northern Africa | 2 (1.3) | 0 (0) | 0 (0) |
| Source type | |||
| Journal article (peer reviewed) | 71 (46) | 30 (31) | 5 (13) |
| Preprint | 13 (8.5) | 8 (8.2) | 4 (11) |
| Presentation, conference or institutional report | 16 (10) | 7 (7.2) | 0 (0) |
| Early results from Unity study collaborators | 53 (35) | 52 (54) | 29 (76) |
| Geographic scope | |||
| National | 40 (26) | 38 (39) | 38 (100) |
| Subnational | 10 (6.5) | 9 (9.3) | – |
| Capital city | 40 (26) | 16 (16) | – |
| Other city or town >3 00 000 people | 11 (7.2) | 4 (4.1) | – |
| Other city or town <3 00 000 people | 49 (32) | 28 (29) | – |
| Multiple cities or towns | 3 (2.0) | 2 (2.1) | – |
| Study population | |||
| Blood donors | 68 (44) | 22 (23) | 22 (58) |
| Residual sera | 9 (5.9) | 4 (4.1) | 2 (5.3) |
| Household and community samples | 70 (46) | 70 (72) | 14 (37) |
| Pregnant or parturient women | 6 (3.9) | 1 (1.0) | 0 (0) |
| Sampling method | |||
| Convenience | 59 (39) | 18 (19) | 3 (7.9) |
| Probability | 78 (51) | 77 (79) | 33 (87) |
| Sequential | 16 (10) | 2 (2.1) | 2 (5.3) |
| Study design | |||
| Cross-sectional survey | 42 (27) | 35 (36) | 13 (34) |
| Prospective cohort | 19 (12) | 19 (20) | 0 (0) |
| Repeated cross-sectional study | 90 (59) | 43 (44) | 25 (66) |
| Retrospective cohort | 2 (1.3) | 0 (0) | 0 (0) |
| Serological test type | |||
| CLIA | 37 (24) | 34 (35) | 2 (5.3) |
| WHO-procured standardised ELISA (Wantai SARS-CoV-2 Total Ab ELISA) | 43 (28) | 35 (36) | 30 (79) |
| Other ELISA | 50 (33) | 7 (7.2) | 4 (11) |
| LFIA | 16 (10) | 15 (15) | 2 (5.3) |
| Multiple types | 5 (3.3) | 4 (4.1) | 0 (0) |
| Other | 2 (1.3) | 2 (2.1) | 0 (0) |
| Overall risk of bias | |||
| Low | 36 (24) | 36 (37) | 25 (66) |
| Moderate | 61 (40) | 61 (63) | 13 (34) |
| High | 56 (37) | – | – |
| Percent vaccinated at sampling midpoint | |||
| 0% | 129 (84) | 75 (77) | 26 (68) |
| Above 0% up to 5% | 18 (12) | 16 (16) | 10 (26) |
| Above 5% up to 10% | 4 (2.6) | 4 (4.1) | 2 (5.3) |
| Above 10% | 2 (1.3) | 2 (2.1) | 0 (0) |
*n (%).
†United Nations, Department of Economic and Social Affairs, Population Division (2018). World Urbanization Prospects: The 2018 Revision, Online Edition. File 13: Population of Capital Cities in 2018 (thousands) and File 16: Percentage of the Total Population Residing in Each Urban Agglomeration with 300 000 Inhabitants or More in 2018, by Country, 1950–2035.
CLIA, chemiluminescent immunoassay; ELISA, enzyme-linked immunosorbent assay; LFIA, lateral flow immunoassay.