Mandeep Singh Dhingra

5 year efficacy of a bivalent killed whole-cell oral cholera vaccine in Kolkata, India: a cluster-randomised, double-blind, placebo-controlled trial

BACKGROUND Efficacy and safety of a two-dose regimen of bivalent killed whole-cell oral cholera vaccine (Shantha Biotechnics, Hyderabad, India) to 3 years is established, but long-term efficacy is not. We aimed to assess protective efficacy up to 5 years in a slum area of Kolkata, India. METHODS In our double-blind, cluster-randomised, placebo-controlled trial, we assessed incidence of cholera in non-pregnant individuals older than 1 year residing in 3933 dwellings (clusters) in Kolkata, India. We randomly allocated participants, by dwelling, to receive two oral doses of modified killed bivalent whole-cell cholera vaccine or heat-killed Escherichia coli K12 placebo, 14 days apart. Randomisation was done by use of a computer-generated sequence in blocks of four. The primary endpoint was prevention of episodes of culture-confirmed Vibrio cholerae O1 diarrhoea severe enough for patients to seek treatment in a health-care facility. We identified culture-confirmed cholera cases among participants seeking treatment for diarrhoea at a study clinic or government hospital between 14 days and 1825 days after receipt of the second dose. We assessed vaccine protection in a per-protocol population of participants who had completely ingested two doses of assigned study treatment. FINDINGS 69 of 31 932 recipients of vaccine and 219 of 34 968 recipients of placebo developed cholera during 5 year follow-up (incidence 2·2 per 1000 in the vaccine group and 6·3 per 1000 in the placebo group). Cumulative protective efficacy of the vaccine at 5 years was 65% (95% CI 52-74; p<0·0001), and point estimates by year of follow-up suggested no evidence of decline in protective efficacy. INTERPRETATION Sustained protection for 5 years at the level we reported has not been noted previously with other oral cholera vaccines. Established long-term efficacy of this vaccine could assist policy makers formulate rational vaccination strategies to reduce overall cholera burden in endemic settings. FUNDING Bill & Melinda Gates Foundation and the governments of South Korea and Sweden.

A multicenter prospective hospital-based surveillance to estimate the burden of rotavirus gastroenteritis in children less than five years of age in India.

BACKGROUND Rotavirus is the leading cause of severe, dehydrating diarrhea in children aged <5 years globally, with an estimated 25 million outpatient visits and 2 million hospitalizations attributable to rotavirus infections each year. The aim of this hospital-based surveillance was to summarize the local epidemiological and virological features of rotavirus and to estimate the disease burden in the population under surveillance in India. METHODS During the 16 months surveillance period from April 2011 through July 2012, a total of 4711 children under the age of 5 years were admitted with acute diarrhea at 12 medical centers attached to medical schools throughout India. Stool samples were randomly collected from 2051 (43.5%) subjects and were analyzed for rotavirus positivity using commercial enzyme immunoassay kit (Premier Rotaclone Qualitative Elisa) at the respective study centers. Rotavirus positive samples were genotyped for VP7 and VP4 by reverse-transcription polymerase chain reaction (RT-PCR) at a central laboratory. RESULTS During the study period, maximum number of rotavirus related hospitalizations were reported from December 2011 through February 2012. Out of the 2051 stool samples tested for rotavirus, overall 541 (26.4%) samples were positive for rotavirus VP6 antigen in stool. The highest positivity was observed in the month of December, 2011 (52.5%) and lowest in the month of May, 2011 (10.3%). We found that majority of the rotavirus positive cases (69.7%) were in children <24 months of age. The most common genotypes reported were G1 (38%), G2 (18%), G9 (18%), G12 (9%) and mixed strains (17%). CONCLUSIONS The results of this study confirm the significant burden of acute rotavirus gastroenteritis as a cause of hospitalizations in under five children in India.

The oral cholera vaccine Shanchol™ when stored at elevated temperatures maintains the safety and immunogenicity profile in Bangladeshi participants.

BACKGROUND The oral cholera vaccine (OCV), Shanchol™ has shown protective efficacy lasting up to 5 years, however, requirement for a cold chain limits its use in resource poor settings. The study was conducted to determine the safety and immunogenicity of Shanchol in adult participants in Bangladesh when stored at elevated temperatures. METHODS The study was conducted in Mirpur, Dhaka. Four groups of healthy adult participants received two doses of Shanchol™, kept under standard storage temperature (Group A; 2-8°C) or at elevated temperatures (Group B, 25°C; Group C, 37°C; Group D, 42°C) for 14 days, respectively. Vaccine specific antibody responses were determined. FINDINGS 145 participants were assigned to each group. Adverse events were mild not differing among groups. Vaccine stored at elevated temperatures remained stable with cumulative LPS content within admissible limits. Vibriocidal antibody responses were observed in all groups after each dose of vaccine at day 7 and 21 compared to pre-immune levels (P<0.001). Four-fold increases to Vibrio cholerae O1 Ogawa were observed at day 7 and/or day 21 after vaccination in the standard temperature and the three elevated temperature groups, with responder rates of; 76% (95% CI LB; 70%), 80% (95% CI LB; 74%), 69% (95% CI LB; 63%), and 74% (95% CI LB; 68%) in Groups A-D, respectively (P=0.240). Responses were also seen in all groups to V. cholerae O1 Inaba and V. cholerae O139 and in LPS specific IgA response to V. cholerae O1 antigens. INTERPRETATION This is the first report to show that the OCV is stable at elevated temperatures, and the safety and immunogenicity profiles are not altered. This information will help formulate global policies for use of the vaccine at higher temperatures, resulting in easier distribution and vaccination costs and decrease logistical challenges to vaccine delivery. FUNDING Bill & Melinda Gates Foundation. TRIAL REGISTRATION Clinical Trials.gov number NCT01762930.

Flexibility of Oral Cholera Vaccine Dosing—A Randomized Controlled Trial Measuring Immune Responses Following Alternative Vaccination Schedules in a Cholera Hyper-Endemic Zone

Background A bivalent killed whole cell oral cholera vaccine has been found to be safe and efficacious for five years in the cholera endemic setting of Kolkata, India, when given in a two dose schedule, two weeks apart. A randomized controlled trial revealed that the immune response was not significantly increased following the second dose compared to that after the first dose. We aimed to evaluate the impact of an extended four week dosing schedule on vibriocidal response. Methodology/Principal Findings In this double blind randomized controlled non-inferiority trial, 356 Indian, non-pregnant residents aged 1 year or older were randomized to receive two doses of oral cholera vaccine at 14 and 28 day intervals. We compared vibriocidal immune responses between these schedules. Among adults, no significant differences were noted when comparing the rates of seroconversion for V. cholerae O1 Inaba following two dose regimens administered at a 14 day interval (55%) vs the 28 day interval (58%). Similarly, no differences in seroconversion were demonstrated in children comparing the 14 (80%) and 28 day intervals (77%). Following 14 and 28 day dosing intervals, vibriocidal response rates against V. cholerae O1 Ogawa were 45% and 49% in adults and 73% and 72% in children respectively. Responses were lower for V. cholerae O139, but similar between dosing schedules for adults (20%, 20%) and children (28%, 20%). Conclusions/Significance Comparable immune responses and safety profiles between the two dosing schedules support the option for increased flexibility of current OCV dosing. Further operational research using a longer dosing regimen will provide answers to improve implementation and delivery of cholera vaccination in endemic and epidemic outbreak scenarios.

A comparison of immunogenicity and safety of indigenously developed liquid (DTwPHB-Hib) pentavalent combination vaccine (Shan 5) with Easyfive (Liq) and Tritanrix + Hiberix (Lyo) in Indian infants administered according to the EPI schedule

The study was planned to assess and compare the immune response and safety of an indigenous DTPwHB-Hib pentavalent liquid combination vaccine (Shan 5) with Easyfive and Tritanrix HB + Hiberix, the two available pentavalent combination vaccines. Four hundred infants were randomized to receive three doses of either Shan 5 or one of the two comparators. Antibody analysis was performed prior to and four to six weeks post third vaccine dose. Solicited local and systemic events upto three days and unsolicited adverse events in the 30 days follow up period after each dose were recorded. A total of 365 subjects completed the study. Four to six weeks after third dose, 98.32% of the subjects in Shan 5 group had seroprotective Anti PRP-T IgG antibody concentrations (≥0.15 µg/mL) as compared to 100% and 98.94% subjects in Tritanrix HB + Hiberix and Easyfive groups respectively. Seroprotective levels for Anti-HBs (≥10 mIU/mL) were observed in 97.77%, 97.83% and 98.94% subjects in Shan 5, Tritanrix HB + Hiberix and Easyfive groups respectively. Comparable immune responses were observed for the three other components (D, T and P) in all the groups. Four Serious Adverse Events (SAEs) were reported (three with Shan 5 and one with Easyfive), all unrelated to the respective vaccines. Most commonly reported adverse events in all the groups were pain at injection site, mild fever (< 103° F) and minor swelling at injection site. The study proved that Shan 5 was safe and immunogenic compared to the two other licensed vaccines.

Evaluation of safety and immunogenicity of a live attenuated tetravalent (G1-G4) Bovine-Human Reassortant Rotavirus vaccine (BRV-TV) in healthy Indian adults and infants

BACKGROUND Rotavirus infections, prevalent in human populations worldwide are mostly caused by Group A viruses. Live attenuated rotavirus vaccines are highly effective in preventing severe rotavirus gastroenteritis. However, the cost of these vaccines and local availability can be a barrier for widespread adoption in public health programs in developing countries where infants suffer a heavy burden of rotavirus related morbidity and mortality. A phase I/II study was carried out with the long term aim to produce a locally licensed vaccine which is equally safe and immunogenic as compared to available licensed vaccines. METHODS This study was conducted in two cohorts. In the first cohort, 20 healthy adults were administered a single dose of the rotavirus vaccine (highest antigen concentration planned for infants) or placebo and were followed up for 10 days for safety. Following demonstration of safety in adult volunteers, 100 healthy infants were recruited (cohort 2) and randomly divided into five equal study groups. They were administered three doses of either the investigational rotavirus vaccine (BRV-TV) at one of the three antigen concentrations or Rotateq or Placebo at 6-8, 10-12 and 14-16 weeks of age. All infants were followed up for safety till 28 days after the third dose. Immune response to the vaccine, in terms of seroresponse and geometric mean concentrations, was compared across the five study groups. RESULTS Increase in anti-rotavirus serum IgA antibodies from baseline, demonstrated higher immune response for all the three antigen concentrations of BRV-TV vaccine and RotaTeq in comparison with the placebo. Sero-response rates for placebo, BRV-TV dose-levels 10(5.0) FFU, 10(5.8) FFU, 10(6.4) FFU, and Rotateq at 28 days post third dose were 11.1%, 27.8%, 41.2%, 83.3%, and 63.2% respectively using the four-fold or more criteria. The BRV-TV vaccine arm corresponding to the highest antigen concentration of 10(6.4) FFU had a higher sero-response rate compared to the active comparator arm (RotaTeq), 28 days post each vaccine dose. The safety profile was comparable across the treatment groups. CONCLUSIONS Overall, the results showed that all three doses of BRV-TV vaccine were safe, well tolerated and displayed good immunogenicity (dose-response) in healthy Indian infants.

Retrospective surveillance for intussusception in children aged less than five years at two tertiary care centers in India.

BACKGROUND A rotavirus vaccine could soon become part of Indias national immunization program. However the occurrence of intussusception due to rotavirus vaccine is a potential safety concern. This surveillance aimed at the collection of baseline data on childhood intussusception which would facilitate the monitoring of intussusception cases after the introduction of rotavirus vaccines. METHODS We retrospectively reviewed medical records of confirmed intussusception cases in children under the age of five, treated during 2007-2012 at two tertiary care hospitals attached to medical schools in India. Demographic, clinical, diagnostic and treatment practices data were obtained from hospital records. RESULTS Over a five to six year observation period, we identified 187 confirmed cases of intussusception, of which 75% were males. The median age of intussusception was 8 months, and we observed a possible trend in the distribution of cases with the highest number of cases being reported in the month of April and lowest in the month of October. The most common diagnostic methods used were ultrasonography and abdominal radiography with most cases being treated surgically (71%). The median length of hospital stay was 8 days (range 1-40) and mean was 10.2 days. Records of any fatality due to intussusception were not found during the review of the records. CONCLUSIONS This analysis provides an estimate of the baseline data of childhood intussusception prior to the introduction of the rotavirus vaccination as a part of routine immunization in India. A prospective surveillance system using a standardized case definition is needed in order to better examine the incidence of intussusception in developing countries.

Human and bovine rotavirus strain antigens for evaluation of immunogenicity in a randomized, double-blind, placebo-controlled trial of a single dose live attenuated tetravalent, bovine-human-reassortant, oral rotavirus vaccine in Indian adults

A single dose of live attenuated tetravalent (G1-G4) bovine human reassortant rotavirus vaccine (BRV-TV) was administered to healthy Indian adult volunteers, who were assessed for safety and immunogenicity of the vaccine with 3:1 randomization to vaccine or placebo. All 20 adult male volunteers in the study had rotavirus specific serum IgA at baseline. There were no side effects or adverse events reported. Administration of BRV-TV was not associated with fever, diarrhea, or altered liver transaminases. Rotavirus IgA seroconversion post single dose administration was 27%. This study shows that BRV-TV is non-reactogenic, safe and immunogenic in adults. The IgA units estimated for the same sample using human G1P[8] rotavirus strain as the antigen were consistently higher than with the bovine G6P[5] WC3 strain and the human G2P[4] DS-1 strain antigen. The use of different human and bovine rotavirus strains as antigens in a quantitative rotavirus specific serum IgA assay resulted in different estimations of IgA antibody in the same sample.

Evaluation of the immunogenicity and safety of an indigenously developed DTwP-Hib tetravalent combination vaccine (Shan 4) with EasyFourTM in Indian infants administered per EPI schedule: a phase III trial.

The study was planned to assess and compared immunogenicity and safety of an indigenous DTPw-Hib combination vaccine (Shan 4) with EasyFour, the available DTwP-Hib vaccine in India. Overall 210 healthy infants, six to eight weeks of age were randomized to receive three doses of either Shan 4 or EasyFour at 6, 10 and 14 weeks of age. Antibodies were analyzed prior to and four to six weeks post third vaccine dose. Solicited and unsolicited local and systemic events in the follow up period after each dose were recorded. Post vaccination 100% of the infants in Shan 4 and EasyFour groups had seroprotective concentrations of Anti PRP-T IgG antibodies, IgG anti-diphtheria toxoid antibodies and IgG anti-tetanus toxoid antibodies. Following third dose of vaccination 86.99% subjects in the Shan 4 group and 73.85% subjects in the EasyFour group seroconverted for anti-pertussis antibody titres. Two Serious Adverse Events (SAEs) were reported during the course of the study, all unrelated to the respective vaccine administered. Most commonly reported adverse events in both the groups were pain at injection site, mild fever (< 103° F) and minor swelling at injection site. The study proved that Shan 4 was safe and immunogenic compared to the available licensed vaccine.

Safety, immune lot-to-lot consistency and non-inferiority of a fully liquid pentavalent DTwp-HepB-Hib vaccine in healthy Indian toddlers and infants

ABSTRACT Pentavalent combination vaccines are important tools to strengthen the immunization programs in numerous countries throughout the world. A large number of countries have recognized the value of combination vaccines and have introduced whole cell pentavalent vaccines into their immunization programs. A phase III, multi-center, randomized, single blinded study of a fully liquid pentavalent DTwP-HepB-Hib investigational vaccine (Shan5™) was conducted across India in 2 cohorts: 15 toddlers were evaluated for safety and immunogenicity following a single booster dose (Cohort 1) followed by 1085 infants (Cohort 2) evaluated for immunogenicity and safety following 3-dose primary immunization of the investigational vaccine or a locally licensed comparator vaccine (Pentavac SD). Immune consistency analysis among 3 lots of the investigational vaccine, and immune non-inferiority analysis of pooled (3 lots) data of investigational vaccine vs. comparator vaccine were carried out in cohort 2. The vaccines demonstrated comparable safety and immune responses in cohort 1. In cohort 2, equivalent immune consistency among 3 lots was observed for all antigens except whole cell pertussis antigens, where a marginal variation was observed which was linked to the low power of the test and concluded to not have any clinical significance. Immune non-inferiority against the comparator vaccine was demonstrated for all 5 antigens. Safety results were comparable between vaccine groups. This investigational, fully-liquid, whole-cell pertussis (wP) containing new pentavalent vaccine was found to be safe and immunologically non-inferior to the licensed comparator vaccine.