BCG Scar Formation @ 3 Months Following BCG Vaccination in Term Infants @ Acsr Govt. Medical College, Nellore, Andhra Pradesh- A Prospective Observational Study

Abstract

BACKGROUND Tuberculosis is still a challenging global problem and continues to have a significant impact on health care worldwide. {1,2} As per global 2018 TB report, in India, every year, an estimated 2.2 lakh children develop TB illness contributing to 22% of Global TB burden. {3} As Tuberculosis (TB) is a serious public health problem, BCG vaccination remains an essential part of TB prevention strategy especially in children. BCG scar is a surrogate marker of vaccination and an important index in the vaccination program. {1,2} BCG appears to be a promising tool in the prevention of TB in children. There is considerable variation in BCG scar failure rate data, and correlation between BCG scar and vaccination. We wanted to determine the scar failure rate following BCG vaccination in term infants and birth weight > 2 Kg wt., within the first 3 months following BCG vaccination. METHODS It is a prospective observational study conducted among 120 consecutive infants weighing >2 Kg attending the immunization clinic of ACSR Government Medical College Hospital. One infant died and 9 could not complete the follow up as per the protocol; hence, 110 infants were included in the final analysis. All babies were administered 0.1 ml of BCG vaccine intradermal as per protocol and examined at 3 months (12 week) for scar on follow up. BCG scar size was measured both across and along the arm in millimeter using a plastic ruler and the average was calculated. Statistical analysis was done accordingly. RESULTS Majority (105) (95.45%) of neonates developed visible scar after 12 wks., of vaccination and 5 (4.5%) had no visible scar representing scar failure rate of 4.5%. There were 76 (69.09%) males and 34 (30.90%) females. Scar failure rate was 3.9% (3) in males and 5.8% (2) in females showing insignificant difference. Babies weighing >2.5 Kg in the study were 91 (82.72%) and 19 (17.25%) were between 2 to 2.5 Kg who had undergone BCG vaccination. Scar failure rate in babies weighing < 2.5 Kg was 10.5% (3) and 3.2% (2) in babies weighing > 2.5 Kg. Majority 88 (80%) of infants received vaccination within 72 hrs while 13 (11.80%) between 3 to 7 days and rest 9 (8.18%) between 7 to 30 days. Scar failure rate was more in babies vaccinated after 7 days 22.2% (3) compared to babies vaccinated within 7 days 10.1% (2). Majority of the babies in the study 78 (70.90%) were on exclusive breast feeds, 11 (10%) were on formula feeds and 21 (19.09%) were on mixed feeds. Scar failure was 18.8% (2) in formula fed babies and 1.2 % (1) on exclusive breast feeding and 9.5% (2) on mixed feeding. Out of 110 babies, 75 (68.18%) babies had scar size > 1 cm, 26 (23.63%) had scar size < 1 cm and 4 (3.63%) had palpable nodule and no scar 5 (4.5%) representing scar failure rate of 4.5%. CONCLUSIONS Majority of infants (95.45%) developed a scar at 12 weeks post vaccination. The association between BCG scar and vaccination was highly significant. BCG scar formation was not affected by age or gender. Scar failure rate was less in babies vaccinated within 7 days a...