Table 4.
Sensitivity analyses of the observed-to-expected (OE) analysis of Guillain Barré syndrome after mRNA-based or adenovirus vectored COVID-19 vaccinationa
| Countriesb | Observed cases within 21 days (n) | Expected cases within 21 days (n) | OE ratio [95% CI] for the 21-day window | Observed cases within 42 days (n) | Expected cases within 42 days (n) | OE ratio [95% CI] for onset within 42 days |
|---|---|---|---|---|---|---|
| mRNA-based vaccines | ||||||
| Assuming a 50% under-reporting rate in both regions | ||||||
| EU | 522 | 482 | 1.08 [0.96–1.23] | 674 | 964 | 0.70 [0.63–0.77] |
| USA | 1474 | 616 | 2.39 [2.18–2.63] | 1738 | 1233 | 1.41 [1.31–1.52] |
| Assuming that only 55% of the USA and 76% of the EU cases are confirmed GBSc | ||||||
| EU | 198 | 482 | 0.41 [0.35–0.49] | 256 | 964 | 0.27 [0.23–0.30] |
| USA | 405 | 616 | 0.66 [0.58–0.75] | 478 | 1233 | 0.39 [0.35–0.43] |
| Combining both hypotheses | ||||||
| EU | 397 | 482 | 0.82 [0.72–0.94] | 512 | 964 | 0.53 [0.48–0.59] |
| USA | 811 | 616 | 1.32 [1.18–1.46] | 956 | 1233 | 0.78 [0.71–0.84] |
| After adding cases excluded for missing TTOd (N = 137) | ||||||
| EU | NR | NR | 365 | 964 | 0.38 [0.34–0.43] | |
| USA | NR | NR | 978 | 1233 | 0.79 [0.73–0.86] | |
| Adenovirus-vectored vaccines | ||||||
| Assuming a 50% under-reporting rate in both regions | ||||||
| EU | 686 | 94 | 7.30 [5.86–9.09] | 868 | 188 | 4.62 [3.94–5.41] |
| USA | 288 | 25 | 11.51 [7.65–17.32] | 340 | 50 | 6.80 [5.05–9.14] |
| Assuming that only 55% of the USA and 76% of the EU cases are confirmed GBSc | ||||||
| EU | 261 | 94 | 2.77 [2.17–3.54] | 330 | 188 | 1.75 [1.47–2.10] |
| USA | 79 | 25 | 3.17 [2.02–4.96] | 94 | 50 | 1.87 [1.33–2.63] |
| Combining both hypotheses | ||||||
| EU | 521 | 94 | 5.55 [4.43–6.95] | 660 | 188 | 3.51 [2.98–4.13] |
| USA | 158 | 25 | 6.33 [4.15–9.65] | 187 | 50 | 3.74 [2.74–5.11] |
| After adding cases excluded for missing TTOd (N = 223) | ||||||
| EU | NR | NR | 464 | 188 | 2.47 [2.08–2.92] | |
| USA | NR | NR | 363 | 50 | 7.25 [5.40–9.75] | |
CI confidence interval, GBS Guillain Barré syndrome, NR not relevant, OE observed to expected, TTO time to onset
aRefer to Table 3 for the number of doses administered and the background rates of GBS for EU and the USA
bFor EU, all cases regardless of the country and the total number of doses administered in EU as of 15 August 2021
cAccording to Brighton Collaborative Criteria [10]
dAssuming that all cases with missing TTO occurred within 42 days after vaccination