H1N1 Newer Vaccine Usage: Experiences from Karnataka State.

Sir,

An important prevention/mitigation strategy for H1N1 pandemic is vaccinating the at-risk population with pandemic vaccine. Ministry of Health and Family Welfare, Government of India, had imported 1.5 million doses of vaccine to vaccinate selected population among the high risk group; the health care and emergency service personnel's. In response to the H1N1 pandemic, the WHO recommended H1N1 vaccine PANENZA, pandemic vaccine procured from M/s Sanofi Pasteur, France, a split virus inactivated, nonadjuvanted monovalent vaccine against pandemic Influenza was used. PANENZA is a suspension, supplied as 10 doses. It is a colorless liquid, clear to opalescent. It is given as a single dose 0.5 ml intramuscular with the help of an AD syringe. It was supplied by the Government of India to the states, distributed to the districts, and further to vaccination sites on the day of vaccination under adequate cold-chain facilities.(1–3)

Data taken on 31st March 2010 suggest that a total of 132,019 samples were tested in India out of which 30,197 (22.87%) were confirmed cases with H1N1. Among the confirmed cases, Karnataka accounted for 2,217 (7.34%). A total of 1,453 (4.81% of the total confirmed H1N1 cases) deaths from H1N1 occurred in India. Of them, 154 cases were from Karnataka (10.59%).(4) Guidelines, Micro-plan, Reporting format, Monitoring format for implementing the programme were previously not available for this newer vaccine, had to be developed by the authors assisted by Administrative Assistant, NPSP Bangalore, available on website - www. mohfw.h1n1.nic.in. All districts had made meticulous microplan, the beneficiaries were identified as guided by the letter from Government of India.(4) The launch of the programme was preceded by adequate and timely meeting/workshops at all levels and trainings of vaccinators/supervisors.

In spite of considerable apprehension from the beneficiaries in Karnataka, H1N1 vaccine was given in three phases as “Pulse” approach between April and October 2010. Karnataka was supplied with 1,24,200 doses as on 15th March 2010. The present study intends to describe the experience of utilization of H1N1 vaccine in Karnataka from the day of its launch in terms of four key indicators. We measured four key indicators – utilization rate, vaccine wastage factor, adverse events following immunization (AEFI) rate, and exclusion rate at the screening site. This study highlights the feedback received after the vaccination sessions. Secondary data about H1N1 vaccination in each district were obtained from the state headquarters after completion of all the three phases [Table 1].

Table 1

Indicators measured in the study

A total of 1,23,165 health care workers were vaccinated in all districts of Karnataka of which 14,916 beneficiaries were vaccinated in the private networking hospitals. This is specifically mentioned here to depict the hand-in-hand coordination of both the sectors in the success of the programme. The utilization rate improved from 37.99% at the end of phase 1 to 99.17% at the end of Phase 3. The utilization rate was calculated by dividing the number vaccinated in each session by the total vials obtained before the first session. Vaccine wastage factor was 1.05. The vaccine wastage was due to it being supplied in a multidose vial form. AEFI was 1.03/1000. Highest AEFI rate (1.95/1000) seen in phase-2 was probably due to reporting of even minor events during this phase. The beneficiaries in this phase were those who were unvaccinated in phase 1 due to self apprehension to a newer vaccine which is a natural phenomenon initially. They then agreed to take the vaccine after counseling in phase-2. AEFI symptoms were classified(3) according to the guidelines. As compared to the defined rate(1) AEFI rate was found to be very low:

Very common symptoms (headache, body ache, pain at injection site) - 5.8/1000

Common (fever, chills, malaise) - 0.22/1000

Uncommon (purities, articaria, neuralgia, parasthesia, fever with convulsion, encephalomyelitis, neuritis, GBS) - 0.22/1000

Rare (anaphylactic shock) - 0.04/1000

Very rare (Angioedema). Nil

Every case with symptoms suggestive of AEFI was counseled and given appropriate treatment at the study setting itself. Exclusion rate at screening site was 0.63%. Patients with known allergy to egg protein, h/o previous anaphylaxis, h/o previous GBS, etc., as per screening protocol were not given the vaccine.

From the study findings we conclude that the vaccine acceptance is very good among the beneficiaries, the health care workers working in both private as well as government settings, at least in the state of Karnataka. Proper education of the community to report AEFI is necessary for the acceptance of any vaccination drive. In a study done in Spain the authors defined a cohort of people with major chronic conditions to obtain 2010/11 midseason estimates of influenza vaccine effectiveness. The adjusted estimates of the effectiveness of the 2010/11 trivalent influenza vaccine were 31% (95% confidence interval (CI): 20–40%) in preventing medically attended influenza-like illness, and 58% (95% CI: 11–80%) in preventing laboratory-confirmed influenza. The monovalent vaccine in the 2009/10 season had an independent preventive effect against medically attended influenza-like illness (17%, 95% CI: 1–30%).(5) In three clinical trial done in France among adults and elderly subjects, comparable immunogenicity and safety profiles were observed in pandemic A (H1N1) 2009 strain when formulated either as a monovalent or as a component of a seasonal trivalent vaccine.(6) Since AEFI rate, in the current study is low, the vaccine can be used among the high risk groups without much hesitation.