By early 2022, the global outbreak data logged more than 423 million (42,34,37,674) total cases and more than 5 million (58,78,328) deaths around the world. against SARS-CoV-2. Blood samples were analyzed from 374 SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) positive, 772 negative and asymptomatic, and 874 random groups of subjects. We found that the antibody titer was significantly higher (p< 0.0001) in infected and vaccinated group compared to the only vaccinated and only infected group. Using enzyme-linked immunosorbent assay Rifamycin S (ELISA), we detected SARS-CoV-2 immunoglobulin G (IgG) antibodies in 118/123 (96%) infected individuals, 570/653 (87%) non-infected but vaccinated individuals, 231/237 (97%) individuals who were both infected and vaccinated, and 499/874 (57%) from randomly selected individuals from the first and second waves of the pandemic. Similarly in the third wave, 14/14 (100%) infected and 16/20 (80%) RT-PCR-negative but symptomatic subjects were detected. Thus, the highly sensitive and specific in-house developed ELISA antibody detection kit CoroSuchak is extremely useful to determine the seroprevalence of SARS-CoV-2 antibodies in the coronavirus-exposed population. == Key points == Indigenous kit using a combination of spike and nucleocapsid proteins and peptide sequences. High sensitivity and specificity to detect variants. Highly sensitive for mass screening. == Supplementary Information == The online version contains supplementary material available at 10.1007/s00253-022-12113-8. Keywords:COVID-19, Antibody detection, Human, IgG, ELISA, Mass screening == Introduction == Multiple human instances of new coronavirus infections were reported in the Huanan Seafood Wholesale Market (South China Seafood City Food Market) in Wuhan, China, at the end of 2019 and the beginning of 2020. The virus was identified as a novel coronavirus on January 7, 2020, and was officially named 2019nCoV, the new coronavirus, and the World Health Organization (WHO) declared it a pandemic on March 12, 2020 (WHO2020a), as Rifamycin S it caused unprecedented disruption on a global level. The first wave of infection Rabbit polyclonal to LIN41 caused by dominant circulating strain Alpha B.1.1.7 and Beta all over the world lasted for 5 to 6 months in 2020, claiming more than 640 Rifamycin S thousand deaths globally (Giuliana Viglione2020). Fortunately, there was a period Rifamycin S of 6 to 7 months after the first wave when the infection rate was reduced worldwide. Before people could recover physiologically, psychologically, and economically from the devastating time of the year 2020, another potent strain of the coronavirus, the Delta strain, attacked the world with a second wave, causing havoc and claiming lives irrespective of age and gender for nearly 4 to 5 months from March to July 2021. Again, there was a lull period of 4 months to recover from the dreaded disease, but yet again, another strain Omicron appeared globally in the third wave from late December 2021. The virus spread across continents in a Rifamycin S short time, infecting about 215 countries and territories. By early 2022, the global outbreak data logged more than 423 million (42,34,37,674) total cases and more than 5 million (58,78,328) deaths around the world. India itself has reported over 42 million cases and over 5.12 million deaths to date. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a member of theCoronaviridaefamily. Coronaviruses (CoVs) are a large group of enclosed, single-stranded RNA viruses that mostly infect humans and animals, causing respiratory problems of varying severity (Chen et al.2020). CoVs are enveloped, non-segmented viruses with a genome size ranging from 26 to 32 kilobases, the largest known viral RNA genome. The nucleocapsid region (N), made up of genomic RNA and phosphorylated nucleocapsid protein, is concealed inside phospholipid bilayers and protected by spike protein (S). SARS-CoV-2 infects human target cells with its viral trans-membrane S protein, a trimeric class-I fusion protein. The S1 makes it easier for the virus to attach to the host entry receptor angiotensin-converting enzyme 2 (ACE2), while the S2 subunit makes it possible for the viral and human cellular membranes to fuse (Hoffmann et al.2020; Zhou et al.2020). S protein is a crucial target for the development of specific medical therapies or vaccines because of its important role. SARS-CoV-2 have a long incubation period of 214 days. Specific immunoglobulin M (IgM) and immunoglobulin A (IgA) antibodies are the early antibody responses that begin and peak within 7 to 10 days, followed by specific immunoglobulin G (IgG) a few days later (between 10 and 18 days) and are assumed to continue as protective antibodies for the rest of the life without.