TABLE 2. Circulating vaccine-derived poliovirus outbreaks (N = 149) and timeliness of outbreak control, by serotype and year of confirmation — worldwide, August 2016–December 2022.
| cVDPV type | Year of outbreak confirmation, no. (%) |
||||||
|---|---|---|---|---|---|---|---|
| 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022* | |
| Type 1 |
—† |
— |
1 |
4 |
1 |
3 |
1 |
| Type 2 |
2 |
4 |
7 |
41 |
49 |
24 |
8 |
| Type 3 |
— |
— |
1 |
— |
— |
2 |
1 |
|
Overall
|
2
|
4
|
9
|
45
|
50
|
29
|
10
|
|
Controlled within 120 days of outbreak confirmation (n = 85 [57%])
| |||||||
| Type 1 |
— |
— |
0 (—) |
4 (100) |
0 (—) |
1 (33) |
0 (—) |
| Type 2 |
2 (100) |
3 (75) |
1 (14) |
24 (59) |
27 (55) |
16 (67) |
4 (50) |
| Type 3 |
— |
— |
0 (—) |
— |
— |
2 (100) |
1 (100) |
| Overall | 2 (100) | 3 (75) | 1 (11) | 28 (62) | 27 (54) | 19 (66) | 5 (50) |
Abbreviation: cVDPV = circulating vaccine derived poliovirus.
* Data as of February 14, 2023. To account for potential low-level transmission continuing after the outbreak response and delayed detection, cVDPV outbreaks were suppressed if <6 months had elapsed from the 120th day following outbreak confirmation (April 20, 2022).
† Dashes indicate that no outbreaks were confirmed during that year.