TABLE 1.

MLVA typing results for clinical B. pertussis isolates in the United Kingdom from different time periods

Period(s)DescriptionYr isolatedNo. of isolatesNo. of MLVA typesDIa (95% CI)No. of new types (no. of unique types)b%c
1Prevaccination1920-195668200.88 (0.84-0.93)NAd (10)NA
2Early postvaccination (WCV)1963-19671350.69 (0.48-0.91)3 (1)60
3Epidemic1977-1986161260.84 (0.80-0.89)19 (13)73
4Vaccination recovery1998-2001110160.65 (0.60-0.71)7 (3)44
5After ACV booster addition2002-2004185180.52 (0.43-0.61)9 (6)50
6After complete switch to ACV2005-2006166240.50 (0.40-0.59)11 (11)46
1-6All periods1920-2006703690.79 (0.76-0.82)NANA
2-6All postvaccination periods1963-2006635590.75 (0.71-0.78)NANA
  • a Hunter and Gaston's modification of Simpson's DI (19), calculated from MLVA types.

  • b Number of MLVA types first appearing during this period (number unique to this period).

  • c Number of new MLVA types divided by total number of MLVA types seen in the given period, expressed as a percentage.

  • d NA, not applicable.