Table 3.
HRs for the incidence of SARS-CoV-2 infection stratified by month* since the start of follow-up
|
Natural infection cohort† |
mRNA-vaccinated cohort† |
Natural infection versus mRNA vaccination (ref) |
||||
|---|---|---|---|---|---|---|
| n | Cumulative incidence, % | n | Cumulative incidence, % | Unadjusted HR | Adjusted HR‡ | |
| Natural infection versus BNT162b2 vaccination study§ | ||||||
| Month 1 of follow-up (month 4 after primary infection or first-dose vaccination) | 79 187 | 0·2% (0·2–0·3) | 79 066 | 0·5% (0·4–0·5) | 0·55 (0·47–0·65) | 0·55 (0·46–0·65) |
| Month 2 of follow-up (month 5 after primary infection or first-dose vaccination) | 62 980 | 0·6% (0·5–0·6) | 62 640 | 1·2% (1·1–1·3) | 0·45 (0·39–0·53) | 0·44 (0·38–0·51) |
| Month 3 of follow-up (month 6 after primary infection or first-dose vaccination) | 55 459 | 0·9% (0·8–0·9) | 54 898 | 1·9% (1·8–2·0) | 0·41 (0·34–0·49) | 0·39 (0·33–0·46) |
| Month 4 of follow-up (month 7 after primary infection or first-dose vaccination) | 50 483 | 1·1% (1·1–1·2) | 49 681 | 2·7% (2·6–2·8) | 0·33 (0·27–0·40) | 0·32 (0·26–0·39) |
| Month 5 of follow-up (month 8 after primary infection or first-dose vaccination) | 44 462 | 1·6% (1·5–1·7) | 43 399 | 4·0% (3·8–4·1) | 0·34 (0·29–0·39) | 0·33 (0·28–0·38) |
| Month 6 of follow-up (month 9 after primary infection or first-dose vaccination) | 35 989 | 3·2% (3·0–3·3) | 34 458 | 7·0% (6·8–7·3) | 0·49 (0·44–0·54) | 0·48 (0·43–0·53) |
| Month 7 of follow-up (month 10 after primary infection or first-dose vaccination) | 27 901 | 6·7% (6·4–6·9) | 25 513 | 13·7% (13·3–14·0) | 0·50 (0·47–0·54) | 0·49 (0·46–0·53) |
| Month 8 of follow-up (month 11 after primary infection or first-dose vaccination) | 22 565 | 8·7% (8·4–9·0) | 19 923 | 17·2% (16·8–17·6) | 0·55 (0·49–0·61) | 0·54 (0·49–0·60) |
| Month 9 of follow-up (month 12 after primary infection or first-dose vaccination) | 18 104 | 9·5% (9·2–9·8) | 15 620 | 18·6% (18·1–19·0) | 0·50 (0·42–0·60) | 0·49 (0·41–0·59) |
| Month 10 of follow-up (month 13 after primary infection or first-dose vaccination) | 12 093 | 9·7% (9·3–10·0) | 10 139 | 18·9% (18·4–19·3) | 0·49 (0·32–0·76) | 0·47 (0·30–0·73) |
| Natural infection versus mRNA-1273 vaccination study§ | ||||||
| Month 1 of follow-up (month 4 after primary infection or first-dose vaccination) | 50 026 | 0·1% (0·1–0·2) | 50 005 | 0·2% (0·2–0·3) | 0·68 (0·51–0·91) | 0·68 (0·51–0·90) |
| Month 2 of follow-up (month 5 after primary infection or first-dose vaccination) | 41 721 | 0·4% (0·4–0·5) | 41 617 | 0·7% (0·6–0·8) | 0·55 (0·44–0·69) | 0·54 (0·43–0·68) |
| Month 3 of follow-up (month 6 after primary infection or first-dose vaccination) | 38 972 | 0·8% (0·7–0·9) | 38 779 | 1·3% (1·2–1·4) | 0·58 (0·47–0·71) | 0·57 (0·46–0·70) |
| Month 4 of follow-up (month 7 after primary infection or first-dose vaccination) | 37 030 | 1·0% (0·9–1·1) | 36 661 | 2·1% (2·0–2·3) | 0·33 (0·26–0·41) | 0·33 (0·26–0·41) |
| Month 5 of follow-up (month 8 after primary infection or first-dose vaccination) | 33 544 | 1·5% (1·4–1·6) | 32 852 | 3·6% (3·4–3·7) | 0·33 (0·27–0·39) | 0·32 (0·27–0·38) |
| Month 6 of follow-up (month 9 after primary infection or first-dose vaccination) | 28 054 | 3·0% (2·9–3·2) | 26 943 | 6·7% (6·5–7·0) | 0·45 (0·40–0·51) | 0·44 (0·40–0·50) |
| Month 7 of follow-up (month 10 after primary infection or first-dose vaccination) | 21 701 | 6·7% (6·4–7·0) | 20 036 | 12·7% (12·3–13·1) | 0·58 (0·53–0·62) | 0·57 (0·53–0·62) |
| Month 8 of follow-up (month 11 after primary infection or first-dose vaccination) | 17 436 | 7·7% (7·4–8·0) | 15 781 | 14·1% (13·7–14·5) | 0·68 (0·58–0·81) | 0·68 (0·58–0·81) |
| Month 9 of follow-up (month 12 after primary infection or first-dose vaccination) | 13 610 | 7·8% (7·5–8·2) | 12 230 | 14·3% (13·9–14·7) | 0·81 (0·49–1·36) | 0·82 (0·49–1·37) |
| Month 10 of follow-up (month 13 after primary infection or first-dose vaccination) | 8651 | 7·9% (7·6–8·2) | 7669 | 14·3% (13·9–14·8) | 0·70 (0·26–1·87) | 0·66 (0·25–1·78) |
95% CIs for HRs and cumulative incidence rates are shown in parentheses. HR=hazard ratio.
A month was defined as 30 days; documented primary infection (natural infection cohort) could have occurred up to a week after first-dose vaccination (vaccinated cohorts) within a matched pair, with follow-up starting 90 days after the primary infection.
Cohorts were exact matched (1:1) by sex, 10-year age group, nationality, comorbidity count, and timing of primary infection or first-dose vaccination.
Cox regression analysis adjusted for sex, 10-year age group, ten nationality groups, comorbidity count (table 1), and timing of primary infection or first-dose vaccination.
No results were generated for months 1–3 after primary infection or first-dose vaccination. This is because a SARS-CoV-2 reinfection is conventionally defined as a documented infection occurring at least 90 days after an earlier infection, to avoid misclassification of prolonged PCR positivity as reinfections;6, 8, 9 therefore, cohorts were followed up starting from 90 days (3 months) after the documented primary infection.