Table 2.
Rates of previously infected (PI) individuals in cohorts infected with different variants of SARS-CoV-2 stratified by vaccination status
| Study | Country/Study type | Description | Negative cohorts % (n/N) |
Delta (or other) infected cohorts % (n/N) |
Omicron infected cohorts % (n/N) or % (n) |
P value |
|---|---|---|---|---|---|---|
| Eggink et al. [35] |
Netherlands Case only approach cohort study |
Naïve (no PI no vaccine) | - |
37.1% (34,765/93734) |
27.4% (22,071/80615) | NR |
| PI unvaccinated | - |
1.4% (1295/93734) |
6.5% (5253/80615) | NR | ||
| Andeweg et al. [61] |
Netherlands Cohort study Of the infected people the presented % were: |
Naïve (no PI no vaccine) |
30.2% (90,945/300849) | 52.8% (21,042/39889) | 24.7% (3440/13915) BA.1 | NR |
| PI unvaccinated | 4.2% (12,691/300849) | 1.6% (638/39889) | 5.3% (739/13915) BA.1 | NR | ||
| First start primary vaccination, then infection | 1.1% (3406/300849) | 0.2% (76/39889) | 1.7% (240/13915) BA.1 | NR | ||
| First infection, then primary vaccination | 2.3% (7002/300849) | 0.3% (139/39889) | 2.1% (293/13915) BA.1 | NR | ||
| PI, booster | 0.3% (918/300849) | 0% (2/39889) | 0.5% (65/13915) BA.1 | NR | ||
| Kahn et al. [45] |
Sweden Cohort study |
PI unvaccinated (0–1 dose) | - | 2.7% (265/9680) | 7.1% (562/7861) PI | NR |
| Vaccinated (2–3 dose) | - | 2.3% (94/4031) | 6.3% (1376/21678) PI | NR | ||
| Kislaya et al. [46] |
Portugal Data linkage Case-case study |
Naïve (no PI no vaccine) |
- | 10.6% (888) | 6% (315) | NR |
| PI unvaccinated | - | 1.3% (108) | 6.2% (327) | NR | ||
| No PI partial vaccination | - | 1.3% (112) | 1.3% (68) | NR | ||
| PI partial/complete vaccination | - | 0.3% (25) | 0.84% (44) | NR | ||
| No PI complete vaccination | - | 88.6% (7245) | 85.7% (4515) | NR | ||
| Nunes et al. [39] |
South Africa Cohort study |
PI | 41.6% (101) | - | 27.9% (53) | 0.003 |
| Naïve (no PI no vaccine) | 10.8% (23) | - | 13.2% (23) | NR | ||
| PI, no vaccines | 6.5% (14) | - | 5.2% (9) | NR | ||
| No PI, J&J | 48.6% (104) | - | 56.9% (99) | NR | ||
| PI + J&J | 34.1% (73) | - | 24.7% (43) | NR | ||
| Spensley et al. [41] |
UK Cohort study |
PI overall | 53.5% (516/965) | - | 43.4% (63/145) | 0.024 |
| PI + ChAdOx1 | - | - | 46.2% (226/489) | 0.75 | ||
| PI + BNT1262b2 | - | - | 47.2% (260/551) | 0.75 |
N Total number of subjects in the cohort
n number of subjects who were PI or as specified in each row