Country | Period | Comment | Year of Isolation | Number of strains |
---|---|---|---|---|
Netherlands | NV | vaccine strains | Â | 2 |
Netherlands | N1 | pre-vaccination period | 1949-1953 | 11 |
Netherlands | N2 | Early post vaccine WCV | 1953-1964 | 5 |
Netherlands | N3 | late post vaccine WCV | 1965-1975 | 6 |
Netherlands | N4 | vaccine dose reduction period | 1976-1984 | 16 |
Netherlands | N5 | post vaccine dose reduction period | 1985-1992 | 15 |
Netherlands | N6 | Epidemic | 1993-2004 | 31 |
Netherlands | N7 | Early post ACV | 2005-2008 | 18 |
Sweden | Sw1 | Post WCV | 1953-1978 | 5 |
Sweden | Sw2 | Vaccine free period | 1979-1996 | 7 |
Sweden | Sw3 | Post ACV | 1997-2008 | 8 |
Japan | J1 | Post WCV | 1949-1981 | 1 |
Japan | J2 | Post ACV | 1982-2008 | 7 |
Australia | A1 | Post WCV | 1950-1998 | 15 |
Australia | A2 | Post ACV | 1999-2008 | - |
Senegal | Se1 | Vaccine free period | until 1987 | - |
Senegal | Se2 | Early post WCV | 1988-2008 | 10 |
Kenya | K1 | Vaccine free period | until 2008 | 13 |
 |  | Reference strain, Tohama I |  | 1 |