Monkeypox belonging to the genus Orthopoxvirus (OPV) of the family poxviridiae poses a major human threat even after 30 years after eradicating smallpox. OPV family includes other viruses like vaccinia virus (VACV), variola virus and cowpox virus. VACV smallpox vaccine provided cross protective antibody response against other orthopox viruses.1 The ongoing monkeypox outbreak has affected 31,800 people in more than 89 different countries. India has documented 9 confirmed cases with one death reported.2 Stockpile of smallpox vaccines that contain live vaccinia virus is maintained at two locations, one at Centre for Disease Control laboratory at Atlanta, Georgia and the other at VECTOR institute, Koltsovo, Russia. Data shows effectiveness of Smallpox vaccines against monkeypox to be 85%.3 Vaccine used in smallpox eradication were first generation vaccines which produced multiple side effects like eczema, progressive vaccinia and myopericarditis. This fear of adverse effects and safety concerns had led to the production of second and third generation vaccines like imvanex or ACAM2000.4 The interim guidelines for monkeypox vaccination does not urge the need for mass vaccination considering the side effects and the vaccine production. Countries like Canada, United Kingdom and USA are using ring vaccination to prevent monkeypox. The two vaccines currently being used against monkeypox are Jynneos vaccine and ACAM2000.5 JYNNEOS vaccine (Imvamune in Canada /Imvanex in Europe developed by Bavarian Nordiac) for adults aged 18 years and older was approved in Europe and U.S. The vaccine contains a replication deficient live vaccinia virus (Modified vaccinia Ankara-MVA BN) that is given as subcutaneous injection of 0.5 ml, two doses four weeks apart. The vaccine is used for post exposure prophylaxis against monkeypox virus. CDC recommends the intermediate or high risk group as potential group to receive post exposure propylaxis of the vaccine (Unprotected contact with the body fluid of infected person or contact with less 6 meter distance with the infected person). Vaccine is available in countries like Canada, Europe and Britain.6 ACAM2OOO, containing live replicating vaccinia virus that can replicate as compared to jynneos vaccine. Owning to the side effects associated with the vaccine its only used for laboratory workers handling pox viruses or for military personnel.4,7,8 WHO has stated there is no need for mass vaccination and decision regarding vaccination should be based on the individual case accessing the risk and benefits.5 In India, the Serum Institute of India has confirmed its ongoing research to find vaccine against monkeypox. Monkeypox vaccine pipelines include 1. Tonix Pharmaceuticals Holding Corp TNX-8011, a preclinical live virus, which uses horsepox virus 2. EpiVax, Inc’s-Epitome driven vaccine 3. VennVax, DNA prime peptide boost multi-T cell epitome Pox virus vaccine.9

Health care workers (HCW) are a high-risk population for Hepatitis B infection. Hepatitis B vaccine which is 95% effective confers long-term protection and anti-HBs titre is a marker for protective immune response. Our objective was to assess the status of hepatitis B vaccination and to evaluate the anti-HBsAg titres among health care workers in a tertiary care hospital, Tamil Nadu. It was an observational study conducted among 610 Health care workers in a tertiary care teaching hospital from June to December 2018 after obtaining clearance from IEC. Workers were assessed for their HBV vaccination status and for their anti-HBsAg titre after getting informed consent. The antibody titres were measured using CLIA (chemiluminescent Immunoassay) supplied by Abbott diagnostics. The data was entered and analyzed using a Microsoft Excel sheet. In our study, 80.5% were fully vaccinated, 18.5% of them were defaulters which comprised the HCW with 2 doses and 1 dose of vaccine and 0.9% were not vaccinated. In the fully vaccinated group, 37% showed Anti HBs titres of 10-100 mIU/ml, 59.2% showed the titre of > 100 mIU/ml and 3.6% did not show the protective antibody titre (<10 mIU/ml ). The 3.6% who did not show protective antibody titre were given the booster dose of vaccine. Among those who received a booster dose, 61.1% responded with the titre of 10-100 mIU/ml and 22.2% responded with the titre of > 100 mIU/ ml and 16.6% did not respond even with the booster dose. In the defaulters 86.7% had titres < 10 mIU/ml , 9.7% had titres of 10 mIU/ml and 3.6% had titres > 10 mIU/ml. In the non vaccinated group all had titres < 10 mIU/ml. The present study emphasizes the importance of screening of anti-HBsAg titres to be made mandatory for all the health care workers along with HBV Vaccination.

ChAdOx1 nCoV-19 Vaccine (Covishield) has shown good efficacy data but the presence of non responders to the vaccine and the duration of protection conferred by the vaccine has not been clearly documented. To study the immunological response to ChAdOx1 nCoV-19 Vaccine among Health Care workers (HCWs) at a tertiary care hospital in Chennai. Materials and Methods: A Prospective study was conducted to analyze the duration of protection conferred by ChAdOx1 nCoV-19 Vaccine by testing the serum samples for Anti SARS IgG Antibody to spike protein by EUROIMMUNE ELISA Kit protocol by testing the pre vaccine sample, samples 2 weeks and 4 weeks following 1st dose,3 months and 6 months post 2 doses of vaccination and to study the association of waning immune response with comorbidities. A total of 265 Health Care Workers (HCWs) involving Nurses (35%), Doctors (32%), Technical staffs (17%) and House keeping staffs (16%) were included in the study. Majority were in age group of 41-50 Years (33%). Associated comorbidity was noticed in 19 % of HCWs. All 100% had sero conversion 4 weeks following Covishield but only 88 % had sero conversion 2 weeks following the 1st dose of Covishield. 100% of the HCWs had detectable levels of Anti SARS IgG antibody to spike protein 3 months following 2nd dose of Covishield but 6 months post 2nd dose only 90.5 % detectable levels of Anti SARS IgG antibody to spike protein. Among the 9.5% with waning immune response 68% had associated comorbidity like obesity (47%), Diabetes Mellitus (41%), Hyperlipidemia (6%) and Chronic lung disease (6%). It is important to maintain the protective antibody titers by vaccinating all the individuals with booster dose of the vaccine and considering population with comorbidities a high risk group for early priority.