A cross-sectional study was conducted on apparently healthy, unmarried, female HCW of our hospital viz., Students of MBBS, BDS, Laboratory technicians, Staff Nurses and doctor. The age of the participants ranges from 18-28 years. The study was conducted in tertiary care teaching hospital in South Chennai during a period of January to February 2017. Total number of the participants of the study were n=145. The sample size was calculated by using the formula n=4P(1-P)/d² [9] where, n=sample size, P=Expected prevalence (Prevalence of previous study in India), [8] and d=allowable error=5%. After getting Institutional ethical committee approval (Ref:NoSP No9/IEC NO:2/May2014) the study was initiated. Written Informed consent was obtained from each participant. Participants who did not consent were excluded from the study. The unstructured questionnaire was self-developed, based on a review of related literatures [2,6]. The questionnaire was administered on demographic details of the participants like age, sex, area of residence and clinical details like history of vaccination to rubella and previous history of fever with rash or lymphadenopathy were collected [Annexure 1]. Three mL of blood sample was collected and the serum was separated and stored at -20°C. Rubella specific IgG antibody was tested using a commercial IgG ELISA-Enzyme Linked Immunosorbent assay using DS-EIA Anti Rubella–G-Fast, Italy. The test was done and results were calculated and interpreted as per manufacturer’s instruction. The samples showing an IgG antibody titre >10 IU/mL were taken as positive and ≤10 IU/mL as negative as per International guidelines [10]. All the negative samples were retested in duplicates and results were confirmed. All seronegative participants in our study were directed and followed up for vaccination.

The data was analysed statistically using Epi Info version 7.2.

Out of 160 participants enrolled, 15 participants did not give their consent and were excluded. Therefore, the total number of the participants were 145 (n=145). The age of the participants was 18 to 20 years n=122 (84.13%), 21 to 28 years were n=23 (15.8%) and mean age of the participants was 19.6 years [Table/Fig-1]. Among the participants, majority were MBBS students 75/145 (51.72%), followed by BDS students 48/145 (33.10%), Laboratory technicians 12/145 (8.27%), Staff nurses 09/145 (6.2%) and Doctor 01/145 (0.69%) [Table/Fig-2]. Out of 145, 124 (85.52%) were immune to rubella virus and 21 (14.48%) were seronegative for rubella infection [Table/Fig-3]. The maximum participants were of 18-20-year-old n=122 (84.13%), followed by 21-28 years, n=23 (15.8%). The seropositive and seronegative in relation to the age of the participants were displayed in [Table/Fig-4]. From the questionnaires the following results were observed: All the participants were living in urban area at the time of study; none of them had past history of fever with rash or lymphadenopathy and could not recollect their vaccination status.

Rubella is an infectious disease which involves all age groups. HWCs are at high risk of acquiring rubella, unless they have protective level of immunity to rubella. As Rubella infections are commonly a subclinical, there is a risk that infected HCWs may unknowingly transmit the infection to the patients or workers in the hospital. Moreover, infection in antenatal mothers especially in the first trimester leads to devastating consequences in the form of CRS in infants. Even Institutional outbreaks have been reported in Chandigarh and Vellore [11,12].

Our study showed that 21/145 (14.48%) were seronegative for Rubella virus [Table/Fig-2]. This is similar to the study conducted by Velvizhi G et al., in south Tamilnadu, the seronegative for Rubella was (15.6%), Vijayalakshmi P et al., (15%), RajaSundari TA et al., (11.4%), Arunkumar G et al., in Manipal University (16.6%), Asari S et al., in Japan (12.5%) [6-8,13,14], whereas study by Valsan C et al., the seronegativity was 33.8% which was higher than our study [2]. There were studies showing less seronegativity (<10%) viz., Alp E et al., (3%), Aypak C et al., (2.5%), and Celikbas A et al., (1.7%) [15-17]. [Table/Fig-5] shows seronegative % of Rubella Immunity (IgG antibody) among HCW in different places [6-8,13-18].

The surveillance of HCWs against rubella and to vaccinate the susceptible personnel has an important implication in the hospital environment. These results of surveillance in the hospital environment can be extrapolated in the general population also. There are few studies among general population in India were showing similar results among HCWs. A study in Mumbai, among 18-24-year-old college students, in which susceptibility rate of 12% was observed, in Jammu among 11-18-year-old school girls (33%) and Thayyil J et al., in the age group of 13-15 years of young teen girls showed 30% of susceptibility rate [18-20]. These high percentages of susceptibility may be due to the improved socioeconomic status and high standard of living in these states. Hence most of the studies in India showed that the susceptibility to rubella still exist the same in different states (11-33%) almost for a period of 15 years. WHO reports that even if the susceptible level in women is below 10%, there is a chance of CRS in the future [21]. Therefore, with this high level of susceptibility in various regions indicates the high chances of developing CRS in India.

Considering, the age of susceptibility to rubella varies from region to region, in our study the participants were in the age group of 18-28 years [Table/Fig-1]. The seronegativity among 18-20-year-old was n=18 (12.4%) and in 21-28 years n=03 (13%) [Table/Fig-4]. A study by Aypak C et al., revealed that rubella antibodies were lower in HCWs aged less than 30 years than those of in the age of 30-44 years, which was supported by many studies in India [6,8,16]. The prevalence of rubella antibodies may reflect not only the vaccination status but previous infection or booster effect by the wild virus. The lower prevalence of antibodies in HCWs <30 years suggests that vaccination should be reinforced in this age group.

In our study, serosurveillance was carried out only in female HCWs and not in the male population. But study showed that seronegativity was also observed in male group which point out the risk of transmission to non-immune pregnant women from infected male [8]. Also in our study, none of them remember their vaccination status against rubella. On the other hand, a study conducted in Manipal University students showed that 10.5% of those previously vaccinated were having inadequate antibody levels [13]. This shows waning of antibodies after a period of 15-20 years. It has also been documented, in those vaccinated at younger age groups; outbreaks of rubella had noticed which emphasis the need for renewal opportunities for vaccination in older children and adolescence [22].

WHO declared that if seronegativity to Rubella among women even less than 10% will provide a chance of CRS in the future [21]. In our study, like many other serosurveillance studies in developing countries, the seronegative to Rubella in female population is between 10-20%. Henceforth in order to eliminate Rubella, in 2017 MR (Measles-Rubella) campaign was introduced in India, which target a wide group of children (9 months to 15 years), to receive an additional dose of the vaccine regardless of previous vaccination status or history of illness. Also, follow-up campaigns will be executed every 3-5 years which target children born after the last campaign and to sustain a high level of population immunity. This campaign leads to rubella elimination, which is defined as the absence of endemic rubella virus transmission in a defined geographical area for >12 months, as well as the absence of CRS cases associated with endemic transmission in the presence of a well performed surveillance system [23].

The limitations of our study were that we could not reach 100% of the sample size since few students did not give consent.

It is essential to magnify the study in both the sexes and in large number of samples in the age group of 15 years and above.

In our study, the seropositivity to Rubella was 85.52% and seronegativity was 14.48% among young female. This susceptibility rate will significantly lead to CRS in the future if not prevented appropriately. Also, the study concludes that immunisation of HCWs against rubella is an important step regardless of their vaccination status. There is a more chance of exposure to infection and also in transmission of infection in the hospital environment. Hence maintenance of immunity is an essential part of prevention and infection control scheme. The existing female population older than 15 years of age has to be focused. This can be done either by serosurveillance followed by vaccination or vaccination irrespective of their immune status of rubella. This could be a sensitive tool to reduce the risk for CRS in a population.