Health technology assessment of varicella vaccine in the Armed Forces

Background

The Indian Armed Forces, on entry, vaccinates all cadets and recruits with varicella vaccine for the prevention of varicella. This health technology assessment (HTA) report puts forth evidence for HTA of varicella vaccination in the Armed Forces in various domains namely clinical, societal, ethical, economic, and legal.

Methods

The policy question under each domain has been developed according to best-practice methods for HTA. The costs included were hospitalization cost due to varicella infection; training lost cost; the varicella vaccine cost; cost of the side effects of vaccine; and the outbreak investigation cost. The incremental cost-effectiveness ratio (ICER) for varicella cases averted and man-days saved, and quality-adjusted life years (QALYs) gained due to varicella vaccination strategy were calculated.

Results

Evidence suggests a reduction of 81% in hospitalization rates with 19392 man-days saved per 1 lakh population due to varicella vaccination strategy. The ICER for varicella cases averted is estimated to be Rs 56732/- per case averted and Rs 5687/- per man-day saved. QALYs gained due to two-dose varicella vaccination strategy is estimated to be 1152 per 1 lakh population with cost per QALY gained Rs 95735/-.

Conclusion

The study showed a large reduction in hospitalizations and consequently man-days lost after the introduction of the vaccination strategy. The QALYs was another aspect of importance brought out by this study. Thus, a two-dose vaccination strategy for varicella-zoster virus (VZV) for the Armed Forces trainees is a cost-effective policy.

Susceptibility of cadets and recruits to chickenpox: A seroprevalence study

Background

Regular outbreaks of chickenpox are reported among cadets and recruits in the army undergoing training, resulting in morbidity and loss in terms of training days. Vaccination policy in the army mandates that all cadets and recruits be vaccinated against chickenpox on joining the training centers. However, 100% vaccination of trainees is not achieved. Hence, seroprevalence data among cadets and recruits were collected with the aim to assess the need for vaccination against chickenpox.

Methods

The data were collected from cadets and recruits undergoing training in military training centers by simple random sampling. Blood samples were collected from all study participants for IgG enzyme-linked immunosorbent assay for varicella zoster. A structured questionnaire was also used to collect information from all participants.

Results

A total of 2041 cadets and recruits between the ages of 19-29 years were studied of which 96.1% were males. Of all participants, 49.9% were seropositive showing varicella zoster virus (VZV) IgG antibody in the serum, and 29.1% study participants gave positive history of having had varicella in the past. The sensitivity of definite positive history of varicella when compared with presence of VZV IgG antibodies was found to be 55.50% while specificity was found to be 97.17%.

Conclusion

A very large majority of cadets and recruits that joined the army are susceptible to chickenpox. Hence, the risk of repeated chickenpox outbreaks in these training centers remains very high. As the sensitivity of history of past infection of chickenpox is relatively low, it cannot be used as a tool to determine the susceptibility of the trainees to the infection.

COVISHIELD (AZD1222) VaccINe effectiveness among healthcare and frontline Workers of INdian Armed Forces: Interim results of VIN-WIN cohort study

Background

On 16 Jan 2021, India launched its immunization program against COVID-19. Among the first recipients were 1.59 million Health Care Workers (HCWs) and Frontline Workers (FLWs) of the Indian Armed Forces, who were administered COVISHIELD (Astra Zeneca). We present an interim analysis of vaccine effectiveness (VE) estimates till 30 May 2021.

Methods

The VIN-WIN cohort study was carried out on anonymized data of HCWs and FLWs of Indian Armed Forces. The existing surveillance system, enhanced for COVID-19 monitoring, was sourced for data. The cohort transitioned from Unvaccinated (UV) to Partially Vaccinated (PV) to Fully Vaccinated (FV), serving as its own internal comparison. Outcomes studied in the three groups were breakthrough infections and COVID related deaths. Incidence Rate Ratio (IRR) was used to compare outcomes among the three groups to estimate VE.

Results

Data of 1,595,630 individuals (mean age 27.6 years; 99% male) over 135 days was analysed. Till 30 May 21, 95.4% and 82.2% were partially and fully vaccinated. The UV, PV and FV compartments comprised 106.6, 46.7 and 58.7 million person-days respectively. The number of breakthrough cases in the UV, PV and FV groups were 10061, 1159 and 2512; while the deaths were 37, 16 and 7 respectively. Corrected VE was 91.8–94.9% against infections.

Conclusion

Interim results of the VIN-WIN cohort study of 1.59 million HCWs and FLWs of Indian Armed Forces showed a ∼93% reduction in COVID-19 breakthrough infections with COVISHIELD vaccination.

Outbreak control of community acquired pneumonia in a large military training institution

BACKGROUND

Between 09 Jan 2011 to 25 Mar 2011 an outbreak of respiratory illness was reported from a Military Training institution. 52 cases of respiratory tract infection were admitted from this institution. All the cases were trainees between 18 and 21 years of age. Aggressive control measures were instituted along with the investigation of the outbreak to determine the nature of the disease and the causative organism.

METHODS

The investigation of the outbreak was initiated on 08 Mar 2011 when a sudden rise in number of hospital admissions due to respiratory illness was noticed. Epidemiological information was collected from the cases. Routine blood investigations, sputum examination and chest radiograph of suspected cases were done.

RESULTS

Total of 52 cases of respiratory illness were reported during the period of outbreak giving an attack rate of 25.8 per 1000. Out of these 52 cases 23 (44.2%) were radiologically confirmed. Streptococcus pneumoniae was grown in 8 (25.85) out of 31 sputum samples. The outbreak was controlled by administration of 'supervised mass chemoprophylaxis' of all susceptible individuals in the institution with Tablet Azithromycin orally. Last suspected case was admitted to the military hospital on 25 Mar 2011.

CONCLUSION

The study highlights the importance of Streptococcus pneumoniae as a causative organism for outbreaks of community acquired pneumonia (CAP) in large residential training institutions and reiterates the need for formulating a policy for continuous surveillance. It also highlights the importance of the novel method of using chemoprophylaxis for control of an ongoing outbreak of CAP.

A Laboratory Investigation into Oviposition Responses of Aedes aegypti to Some Common Household Substances and Water from Conspecific Larvae

BACKGROUND

The surveillance of Dengue vector - Aedes aegypti, is routinely done by using ovitraps (a dark container filled with water and a wooden paddle/towel cloth provided as a oviposition substrate), which indicates the extent of Aedes activity in an area.

METHOD

The study evaluated the oviposition responses of laboratory bred gravid Aedes aegypti to commonly available household substances by use of ovitrap method.

RESULTS

Oviposition avoidance or deterrence was exhibited by gravid Aedes to ovitraps baited with salt, fenugreek, vinegar, lime juice, hibiscus leaves, radish and curry leaves, whereas positive oviposition response was noticed to waters from conspecific (of the same species) larvae and cumin seeds baited ovitraps.

CONCLUSION

The study findings may be utilized by researchers for further chemical analysis of the active ingredients of the substances found promising with a view to explore the possibility of their use by community and individuals for Aedes surveillance and control.