ABSTRACT
Introduction: SARS-CoV-2 affected millions of lives globally and led to devastating impact on public health. India had also witnessed the dreadful effect of SARS-CoV-2 pandemic. Within a short span of time, various SARS-CoV-2 vaccines were developed using different platforms across the world. India has also developed one such indigenous whole-virion inactivated SARSCoV-2 vaccine named as BBV152 (Covaxin). The Covaxin has been found to be immunogenic and second most widely used vaccine in India. Recent studies have also shown significant increase in the humoral and neutralizing antibody response post the administration of booster dose against Omicron variant. Apparently, there is limited data on the long-term persistence of the immune response against the Covaxin in Indian context. Method(s): We evaluated an effectiveness of the Covaxin and comparing its specific immune responses in two categories through prospective cohorts recruited at the vaccination centre, Pune during June 2021 to March 2022. We defined the study population in two groups who were COVID-19 naive individuals (group-1) and COVID-19 recovered individuals (group-2) prior to the immunization with Covaxin. The two cohorts and the study participants were decided considering the baseline antibody titres against SARS-CoV-2, the COVID-19 positivity rate, sample power and loss to follow up. The study population was assessed during three follow-ups at second dose, one and six months post second dose to determine the immune response and effectiveness using S1-RBD IgG ELISA and neutralizing antibody response (NAbs) by plaque reduction neutralization test (PRNT). Result(s): We enrolled participants between age group of 18-80 year (median 32 years). In group-1 and group-2, we recruited 118 and 128 participants respectively. The cohort retention was found to be> 85%,>70% and>40% in 1st, 2nd and 3rd follow up respectively. Loss to the 3rd follow up was coincided with third wave with omicron variant. A rise in geometrical mean titre (GMT) of S1-RBD IgG were observed amongst the participants of both the groups at one-month post immunization (Group 1: S1-RBD: 154.4 to 446.3, Group 2 S1- RBD: 918 to 1127). However, the GMTs at six months post vaccination found to be slightly raised in Group 1 compared to one-month follow-up. Considering the hybrid immunity in group 2 participants, the GMTs of NAbs were higher than group 1 participants at each follow-up against B.1, Delta, Omicron BA.1 and BA.2. Both the groups had shown significant reduction in the levels of NAbs against Delta, Omicron BA.1 and BA.2 compared to B.1. The lowest GMTs of NAbs was observed against BA.1 variant. The IgG and NAbs persisted till six months in 90% participants in both categories except BA.1 variant. Breakthrough cases were reported at one-month (n = 1) and six-months (n = 2) post vaccination respectively from group 1. While reinfection cases (n = 3) were detected at six months post vaccination from group 2 due to Omicron BA.1 variant. Conclusion(s): A two-dose regimen of the Covaxin vaccine enhanced humoral immune response in adults with/without past COVID-19 infection and protected more than 90% adults against SARSCoV-2 infection. Additionally, IgG and NAb responses persisted for six months postvaccination.
ABSTRACT
SARS-CoV-2 pandemic has created serious public health issues claiming millions of human lives worldwide. Few vaccines for the control of COVID-19 are now available under emergency user authorization. However, many aspects of SARS-CoV-2 such as vaccine efficacy, pathogenesis, and transmission related to emerging variants still need to be explored. Various animal models have been studied for COVID-19 research. Of these, hamsters and nonhuman primates have been found to be the best models which share highest similarity with human angiotensin converting enzyme 2 (ACE2), the entry receptor for SARS-CoV-2. Both of these animals have been used effectively for testing of vaccines and drugs, and other basic research on this disease. Here, we have discussed the utilization of Syrian hamster and nonhuman primate in COVID-19 research with special focus on preclinical studies on vaccine and drug discovery.
ABSTRACT
India is considered as a hot spot for emerging infectious diseases. In the recent past many infectious diseases of emerging and re-emerging nature have entered this subcontinent and affected a large number of populations. A few examples are Nipah, Avian influenza, Pandemic influenza, severe acute respiratory syndrome corona virus and Chikungunya virus. These diseases have not only affected human and animal health but also economy of the country on a very large scale. During December 2010, National Institute of Virology, Pune detected Crimean-Congo hemorrhagic fever virus specific IgG antibodies in livestock serum samples from Gujarat and Rajasthan states. Subsequently, during January 2011 Crimean-Congo hemorrhagic fever virus was confirmed in a nosocomial outbreak, in Ahmadabad, Gujarat, India. Retrospective investigation of suspected human samples confirmed that the virus was present in Gujarat state, earlier to this outbreak. This disease has a case fatality rate ranging from 5 to 80 %. Earlier presence of hemagglutination inhibition antibodies have been detected in animal sera from Jammu and Kashmir, the western border districts, southern regions and Maharashtra state of India. The evidences of virus activity and antibodies were observed during and after the outbreak in human beings, ticks and domestic animals (buffalo, cattle, goat and sheep) from Gujarat State of India. During the year 2012, this virus was again reported in human beings and animals. Phylogenetic analysis showed that all the four isolates of 2011, as well as the S segment from specimen of 2010 and 2012 were highly conserved and clustered together in the Asian/Middle East genotype IV. The S segment of South-Asia 2 type was closest to a Tajikistan strain TADJ/HU8966 of 1990. The present scenario in India suggests the need to look seriously into various important aspects of this zoonotic disease, which includes diagnosis, intervention, patient management, control of laboratory acquired and nosocomial infection, tick control, livestock survey and this, should be done in priority before it further spreads to other states. Being a high risk group pathogen, diagnosis is a major concern in India where only a few Biosafety level 3 laboratories exist and it needs to be addressed immediately before this disease becomes endemic in India. FAU - Yadav, Pragya D.