Seroprevalence of rubella antibodies among adolescent girls of Mysore district, Karnataka, India

Introduction

Rubella disease, or German measles, is an acute, highly contagious viral infection caused by the rubella virus. Rubella virus contains a single-stranded positive-sense RNA genome.1, 2 Humans are the only known host. It occurs most often in children and young adults and is transmitted by airborne droplets when infected people sneeze or cough. 3

While rubella virus infection usually causes a mild fever (<39°C) and rash illness with nausea and mild conjunctivitis in children and adults. In the first trimester of pregnancy, the disease may result in a lot of complications, including miscarriage, stillbirth, fetal death and infants are born with congenital malformations, known as congenital rubella syndrome (CRS).4

The classical feature of rubella is the swollen lymph glands behind the ears and the neck. As a result, the rash almost occurs in 50 – 80% of the cases. The rash starts on the face and neck and progresses down the body. The rash will last for about one to three days duration. The period of infectivity is usually from first day of the rash till the fifth day after the appearance of the rash.3

There is a high risk (90%) of vertical transmission when a pregnant female gets a rubella infection. Deafness in the child is the most common defect seen, followed by defects in the eyes, heart, and brain.

To ensure protection against vaccine-preventable diseases, the Health Ministry of India has initiated a Measles-Rubella (MR) vaccination campaign. The campaign's main aim is to give one shot of the MR Vaccine to all children aged nine months to 15 years. The Government of India planned to reach more than 400 children in India. The MR vaccination was given irrespective of the earlier vaccine or disease status.

The live attenuated rubella vaccine has been used in immunizing children. There was substantial medical evidence that the vaccine could prevent infection and prevent pregnancy complications, including congenital rubella syndrome(CRS).4 Following a single dose of the rubella vaccine, there is 95% long-lasting immunity, similar to immunity induced by natural infection. 3

The population-level immunity is assessed by doing serological surveillance (serosurveillance). These studies are done as cross-sectional studies to know the antibody prevalence. 5

Most adolescents and women of childbearing age show high rubella seropositivity rates due to childhood exposure. Several seroepidemiological surveys from India have reported that many women reach childbearing age without acquiring natural immunity to rubella, making them more susceptible to infection. 6 So far, only a few studies have been documented on the seroprevalence of healthy adolescent school girls, especially from India. The studies that have been conducted showed variable results. Hence, the current study was conducted to estimate the seroprevalence of rubella in healthy adolescent school girls. It may also enhance our understanding of the vaccination status and guide policy for clinical practice on MR, rubella vaccination.

Materials and Methods

The current study was done among healthy adolescent girls in the age group around 13-16yrs. The school is located in a rural area of the Mysore District. The sample size was calculated assuming the proportion of positive cases for IgM antibodies to rubella virus as 15.2 % as per the study by Ballal, M. et al. 7 The other parameters considered for sample size calculation were 6% absolute precision and 95% confidence level. In addition, an infinite population correction was applied.

The following formula was used for sample size calculation. 8 Where n = Sample size Z= Z statistic for a level of confidence, P = Expected prevalence of proportion.(If the expected prevalence is 15.2%, then P= 0.152), and d = Precision (If the precision is 5%, then d=0.06).

The required number of subjects per the calculation mentioned above was 138. Therefore, with a non-participation rate of about 15% (22 subjects), it was decided to include 160 subjects in the study.

Results

A total of 160 people were included in the analysis. The mean age of the study population was 14.79 ± 0.86 years. The minimum age was 13 years, and the maximum age was 16 years for the study population.(Table 1)

Among the study population, 20 (12.50%) participants were aged 13-14 years, 20 (12.50%) participants were aged 14-15 years, 94 (58.80%) participants were aged 15-16 years, 26 (16.30%) participants were aged 16-17 years. (Table 2)

152 (95%) participants had positive IgG antibodies in the study population. Only 8(5%) participants were tested seronegative for IgG antibodies. (Table 3)

The mean value of IgG titre was 181.46 ± 120.98 in the study population. The range was 5 to 624 (95% CI 162.57 to 200.35). (Table 4) Reference value of IgG taken is <10IU/ml for seronegativity, >10 IU/ml is taken as seropositive.

Among the study population, 69 (43.10%) of the participants belonged to the lower middle class, 77 (48.10%) participants were in the upper-lower class of Modified Kuppuswamy socioeconomic status, and 14 (8.80%) participants belonged to the lower class, and no one belonged to upper socioeconomic status. (Table 4)

25% of seronegativity is seen in the 14 to 15yrs age group, and 75% of seronegativity is seen in the 15 to 16yrs age group. (Table 6)

The mean value was 190.69 ± 117.04 in positive Rubella antibody and 6.18 ± 2.18 in negative Rubella antibody results. The difference between the two groups was statistically significant (P-value <0.001). This indicates that most values were positive and significantly more than the negative results (Table 7)

Among the people with positive Rubella antibody results, 61 (40.1%) participants belonged to the lower middle class, 77 (50.7%) participants belonged to the upper-lower class, and 14 (9.2%) participants belonged to the lower class. Most of the study participants in the current study belonged to the lower types of Kuppuswamy's SES. All the seronegative belonged to the lower middle class (Table 7)

Discussion

There are only a few vaccine-preventable diseases. Rubella, even though it is a highly contagious disease effective vaccine is available. According to sustainable development goals across developing and developed nations, a few goals are directly and indirectly related to health. Sustainable development goals like alleviating poverty and hunger is linked with the burden of disease among the people in a nation. So, economically, moving a country from developing to developed depends on how effectively primary prevention is implemented, irrespective of the class of people benefiting. Zero surveillance studies play a vital role in knowing the effectiveness and coverage of an immunization programme. Surveillance means continuous scrutiny of factors that will help monitor the community's health status. At the same time, there is a need for considerable resources to be allotted in terms of workforce, technology, time and people. The developing nations in the present situation may go through an economic dilemma regarding where the resources have to be allotted. The resources available in poor and developing countries are so limited. Even the vaccination programmes under the universal health coverage theme may not be feasible in such a situation; zero surveillance studies may be restricted. The authorities in such countries involved in policymaking may not find zero surveillance studies convincing. The roadmap to eliminate rubella is not complete without zero surveillance studies, even though the prevalence of rubella disease has decreased due to effective vaccination. Elimination and zero surveillance are synonymous.

Conclusion

The introduction of a countrywide immunization programme began with the essential need to control vaccine-preventable diseases. The effective immunization programme had significantly decreased the morbidity and mortality related to vaccine-preventable diseases. However, there is no mandatory reason to take vaccines for the public. Only health education regarding the disease spectrum and the history of infectious disease control through effective vaccines can change people's attitudes regarding vaccination. Nowadays, we can see a surge in spreading propaganda against vaccination through various social media platforms, which can also adversely affect immunization coverage. The propaganda against vaccination is baseless, and science has consistently produced evidence for universal immunization coverage.

Recommendations

Conflict of Interest

The authors declare no relevant conflicts of interest.

Source of Funding

None.