LOCAL REACTION-DELAYED TYPE HYPERSENSITIVITY RESPONSE AND COMPLICATIONS OF BCG VACCINE PRODUCED IN PASTEUR INSTITUTE OF HCM CITY

 

Mai Nguyet Thu Hong

Pasteur Institute of HoChiMinh City-Vietnam

 

Introduction

Every year, 1.5 million of BCG vaccine doses have been vaccinated to newborns of the Southern Viet Nam. The vaccine is produced in Pasteur Institute of HCM city. Thus, the results of clinical trials for this vaccine is necessary. We report here the delayed type hypersensitivity response, the local reaction and the complications of this vaccine in 1,171 vaccinated newborns with 0.05mg of BCG vaccine produced in Pasteur Institute of HCM city.

Method

1,171 newborns in Tu Du Maternal hospital have been vaccinated with 0.05mg (0.134.106 ± 0,017 colony forming units) of BCG vaccine at the center of left deltoid muscle. After three months, we observe:

1. The positive delayed type hypersensitivity response to 2 IU of PPD RT 23.

This is an induration of more than 6 mm of diameter at the tested tuberculin point. The density of the skin surface induration is harder than that of the others skin surfaces. The border of induration can clear or dull belong to the strong or weak response. The response has been classified in 4 types:

-         First type is a strong response with a clear border and the hard density of induration.

-         Fourth type is a weak response with a diffuse border and the soft density of induration.

-          Second and third type:are the intermediate types of the first and the fourth types.

2 The complications have been expressed with the strong local reactions and many secondary reactions, such as: adenitis suppurative, adenitis non suppurative, otitis, keloid...

2.1. Local reaction:

Observe and measure the local reaction after three months of BCG vaccination and devide it in four types:

-         Scar: is a mark remaining after the healing of local reaction.

-         Crust is an outer layer of solid matter formed by the drying of a bodily exudate in the injection site

-         Abscess is a localized collection of pus in a cavity formed by the distegration of tissues in the injection site

-         Ulcer is a loss of substance on a cutaneous surface in the injection site

The abscess and ulcer will have been observed until six months after BCG vaccination.

2.2. The others secondary reactions

-         Adenitis suppurative: is an inflammation, painless and fistula of a gland related to the injection site such as the cervical or axillary gland.

-         Adenitis non suppurative: is an inflammation, painless of a gland related to the injection site such as the cervical or axillary gland. The dimension of adenitis non suppurative is smaller than that of adenitis non suppurative.

-         The others reactions such as fever, keloid, otitis....

Result

-         94,11% (1,148/1,172) of newborns give the positive delayed type hypersensitivity response. The response is not strong, 32,71% (383/1,171) of first type, 29,89% (350/1,171) of second type, 24,42% (286/1,171) of third type and 7,09% (83/1,171)of fourth type of Palmer classification The dimension of delayed type hypersensitivity response is 11,02 ± 2,56 mm.

-         83,69% (980/1,171) of first type (scar) of local reaction after three months of vaccination, 8,80% (103/1,171) of second type, 5,81% (68/1,171) of third type and 1,71% (20/1,171) of fourth type. 100% of newborns have the beautiful scars after six months. The dimension local reaction is 5,29 ± 0,6 mm

-         0,34% of adenitis suppurative, 0,34% of adenitis non suppurative, 0,09% of keloids.

-         The others reactions have not been detected.

Discussion

-         According to many reports, delayed type hypersensitivity response generally occurs (80%). In comparing to the OMS norm that is more than 50% of positive delayed type hypersensitivity response for an effective BCG vaccine, the BCG vaccine produced in Pasteur Institute of HCM city induces obvious delayed type hypersensitivity response. The strong or weak responses have not been detected. Only 32,71% of first type and 7,09% of fourth type of Palmer classification. The dimension of delayed type hypersensitivity response is 11,02 ± 2,56 mm..

-         The local reaction is not strong, 83,90% is the scars after 3 months and 100% after 6 months of BCG vaccination. The dimension of local reaction is 5,29± 0,6 mm. This dimension is accepted within the OMS norm that is from 5 to 8 mm.

-         The rate adenitis suppurative is 0,34%, that is lower than the others studies and OMS norm that is below 2%. 0,34% of adenitis non suppurative is accepted within in norm that is below 4%. Keloid is rare-0.09%. These results have shown that the complications rate is below the OMS permissible limit.

Conclusion

These reaction have demonstrated that the BCG vaccine produced in Pasteur Institute of HCM City has the expected activity.