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ACADEMIA Letters Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines Prasanta Ghosh Abstract As of March 31, 2021, eight vaccines against COVID-19 flu were approved globally, which include ChAdOx1 (AZS1222) [AstraZeneca/Oxford, UK]; COVAXIN [Bharat Biotech, India]; BNT162b2 [Pfizer-BioNTech, USA]; mRNA-1273 [Moderna, USA]; ADENO 26 CoV2.S [Johnson &Johnson, USA ]; and Sputnik V [Gamaleya Research Institute of Epidemiology and Microbiology, Moscow, Russia]. All are 2- dose vaccines except ADENO 26 CoV2.S, which requires one dose only. As there is yet no effective therapeutic substance to contain the disease, mass vaccination is the only effective alternative to fight the pandemic. Due to the non-availability of an adequate supply of vaccines, countries are resorting to delaying the use of the second dose, which must be deployed before the antibody titer is waned off after the first dose. There is a need to experimentally determine how much delay can be made between the 2 doses. Further, as people over 60y are more vulnerable to the disease, data need to be generated for each vaccine on this population on whether there is any need to reschedule the dosage gaps as also if 3 dose regimens are more efficacious. Keywords: COVID-19 vaccines, approved SARS-CoV-2 vaccines, vaccination efficacy Introduction The Regulatory authorities the world over have approved [1,2] the emergency use of the eight SARS-CoV-2 vaccines as of March-end, 2021 to protect the population from COVID19 flu. The approved vaccines are (1) ChAdOx1 (AZS1222) AstraZeneca/Oxford (UK)invented, Chimpanzee adenoviral vector-based replication-deficient viral vector containing Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 1 the c DNA based expression cassette coding for the SARS-CoV-2 S protein, and the vaccine is known as COVISHIELD requiring 2 doses, 28 days apart; (2) Bharat Biotech’s use of propiolactone-deactivated whole-virion SARS-CoV-2 strain named as NIV-2020-770, which is multiplied in Vero cells. The vaccine is named as COVAXIN by Bharat Biotech and requires 2 doses, 28 days apart for protection. The company has changed the name of the viral strain to BBV152. (3) Sinovac Biotech, China using deactivated whole-virion SARS-CoV-2 strain named as CN02 and multiplied in Vero cells and the vaccine is named as CORONA VAC, requiring 2 doses, 14 days apart; (4) Sinopharm, China using deactivated whole-virion SARS-CoV-2 strain named as HBO2 and multiplied in Vero cells, and the name of the vaccine is BBIBP-Cor V requiring 2 doses, 21 days apart; (5) Pfizer-BioNTech, USA manufacturing lab-synthesized mRNA coding for full-length S protein with proline substitutions, captured inside nano-particles using multiple amphiphilic substances and requiring 2 doses, 21 days apart; the vaccine is named as BNT162b2;(6) Moderna, USA manufacturing labsynthesized mRNA coding for full-length S protein with proline substitutions, captured inside nano-particles using multiple amphiphilic substances and requiring 2 doses, 14 days apart and named as mRNA-1273. The synthesized mRNA, as well as the amphiphilic substances used by Moderna, are different from those of Pfizer;( 7) Johnson &Johnson , USA manufacturing recombinant replication-deficient human adenovirus serotype 26-vector based DNA cassette containing the c DNA-based coding sequence for stabilized full-length SARS-CoV-2 S protein and the name of the vaccine is ADENO 26 CoV2.S , requiring application of two doses 28 days apart, and (8) the two-Adenoviral vector-based r DNA vaccine , using adenovirus type 26 having an insertion of c DNA- based nucleotide sequence coding for the full-length spike protein of SARS-CoV-2 virus ( Ad26) and the adenovirus type 5 , also having an insertion of c DNA- based nucleotide sequence coding for the full-length spike protein of the virus( Ad5). Both the adenoviruses are replication-incompetent. The combo vaccines were invented by the Gamaleya Research Institute of Epidemiology and Microbiology, Moscow. The vaccine initially named as Gam-COVID-Vac was renamed as Sputnik V is required in two doses, 21 days apart. Three of these namely (2), (3),(4) are whole-virion inactivated vaccines; threearerecombinant Adenoviral DNA-base replication-deficient DNA vaccines as at (1),(7), and (8); and two are m-RNA based, nano-particle encapsulated SARS-Co V -2 vaccines as ay (5) and (6). It is not easy to contemplate which ones are the most efficacious ones, which ones are comparatively safer, and which ones are the best ones for individuals. Two other types of injectable COVID-19 vaccines are in the pipeline which includes the use of attenuated SARSCoV-2 strain and the r-DNA derived viral spike protein-based vaccines. Besides, vaccines based on the newer delivery systems such as oral, nasal, skin-patch-based delivery are also under development [3]. Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 2 In the meantime, the COVID-19 flu continues to maintain its pandemic the world over. The world scenario on COVID-19 pandemic as of March 21, 2021, indicated[4] the total infected from the disease was 123,581,422; the total death was 2,724,071, and the total recovered was 99,552,14. India ranked third in terms of death, registering the number of deaths as 1,59,821 with total active cases of 1,16,05,673 and recovered cases of 1,11,32,082. The counties registering deaths more than India were the USA (554889 deaths) followed by Brazil (292856 deaths). World over patients with hypertension, diabetes, coronary heart disease, cerebrovascular illness, chronic obstructive pulmonary disease, and kidney dysfunction have worse clinical outcomes[5] when infected with SARS-CoV-2. There is yet no effective therapeutic substance to contain the disease. Mass vaccination is the only effective alternative to fight the disease. The immediate need is therefore to increase the herd immunity of every community and therefore all eligible individuals must be vaccinated. This is a stupendous task. The aim of the paper is to ascertain how fast the eligible world population in the senior age group above 60y be protected by vaccination; what is an experimentally determined time gap between the 2-dose vaccines; and what are the deciding parameters to ensure the protection of individuals above 60y from the disease. This age group of population is more vulnerable to the disease. Methodology The study was carried out based a table study of relevant literature accessed through the internet by using the Google search engine. The issues All the approved vaccines have been rated as reasonably safe for deployment. The efficacy of each one is, however, considerably different as had been determined from various studies, which has varied [6-10] from over 50% to over 90%. The mRNA vaccines have provided the highest percentage of protection among the recipients, above 90% while the other types provided much lesser protection.. There is no information on what is the protection rate in individuals above 60y of age for each type of vaccine. The mRNA vaccines are highly priced by the owners/suppliers; these are IPR protected and the prices are dictated by the owners. The other ones are moderately priced. Presently, the supply is inadequate and the available production is purchased by the governments; but sooner vaccines would be available in private markets also when more vaccines are approved and supply from the existing and new Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 3 manufacturers increase. Government vaccination programs are aimed at increasing the herd immunity of the community. Any vaccine that is more than 50% efficacious can contribute to raising the herd immunity of the population and governments can fight the pandemic using such vaccines. However, a vaccine with just above 50% efficacy shall take more time to raise the herd immunity than the one that imparts more than 90% efficacy as increased efficacy will contribute to reducing infection among the vaccinated population. Data published from Israel had shown [11] that even when about 90% of people aged 60y and older in the country had received the first dose of Pfizer’s 2-dose vaccine, there was a 41% drop in confirmed COVID-19 infections in that age group. The situation must have improved further after 2 doses were received. While the drop in the newer infection rate is the aim of government programs, senior citizens individually could be curious to ascertain if they have been protected after receiving an approved vaccine in the scheduled doses. Individual protection is important to individuals. There is yet no fool-proof method to ascertain this. Evaluation of the levels of clonal IgM/IgG to the nucleocapsid protein of the SARS-CoV-2 virus is indicative of whether there was an exposure to the virus. Methods for measuring the levels of neutralizing immunoglobulins in the vaccinated individuals against the spike protein of the virus are in place to ascertain if protection is imparted. The development of neutralizing antibodies (nAbs) to the spike protein, especially the receptor-binding domain (RBD) of the virus is the aim of vaccine–induced protective immunity. In a study[12] involving 19860 individuals recovered from COVID-19 flu, the measurement of total antibodies had shown that the about 70% of the individuals had moderate(1:320) to high(1:2880) titers and that over 90% of this population had neutralizing antibodies, specific to spike-proteins of the virus. Among the nAbs formed, which include IgG, IgE, IgM, and IgA, there has been a preponderance[13] of IgA antibodies which may play a dominant role in the control of infection. It can be apprehended therefore that measurement of the levels of circulating neutralizing antibodies of IgA types against the virus might provide a respite to ensuring protection. However, there is yet no well-defined, unanimous, globally accepted, foolproof method of determining whether, after vaccination, individuals have been protected. This information is important and more relevant for the aged individuals who are more than 60y in age. Due to the non-availability of an adequate supply of vaccines, countries are resorting to delaying the use of the second dose. Such delays under the circumstances may be justified provided the second dose is applied within a period when the neutralizing antibody titer emanating from the first dose is not waned off significantly. This change in the re-scheduling may be for bringing in more eligible people within the preview of the first dose so as to increase the number of the protected populations against the disease. The French National Academy of Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 4 Medicine in a press release[14]on Jan11, 2021had recommended a delay between two doses up to 3 weeks. However for this, experimental national and international data need to be generated for each type of vaccine deployed. Theoretically, delaying between the vaccine doses is scientifically improper. There is another complex issue that has surfaced over time from the multiple COVID19 infections. The original[15]SARS-CoV-2 virus has mutated and the mutated strains are developing capacities to evade the vaccine efficacy. The extent of evasion-from-capture by the immune system of the sensitized and immunized individuals is variable and differs from vaccines to vaccines. However, for a given vaccine type, it is anticipated to be in close range in a population. Multiple mutated viral SARS-CoV-2 strains are in circulation[16]in the human population of which some could pose a serious COVID-19 disease risk. Discussion and concluding remarks It is necessary to understand the dynamics of immune cells which are responsible for developing acquired immunity on being exposed to the SARS-CoV-2 virus or an antigen derived from the virus such as the vaccines. The measurement of the activated CD4+T-cells, cytotoxic CD8+ T-cells and the memory B- cells over a period of time after infection would provide insight into the persistence of the magnitude of adaptive immune response and can assist the assessment of the duration of immunity against another infection. Vaccines can also be assessed in the above way to assess their protective potential. In a recent study [17] using human subjects infected with the virus, the dynamics of the above immune cells were studied. It was found that about 95% of the subjects could maintain immune memory at about six months after infection. Interestingly, the circulating antibodies against the SARS-Co V-2 did not correlate with the T-cell memory. Assessment of the protective immunity against the virus has therefore to be carried out by the measurement of the preponderance of the residual T- memory cells, CD4+ T-cells, and CD8+T-cells. Therefore, a set of step-by-step instructions and standard operating procedures (SOPs) are to be evolved as has been done for assessing the COVID-19 disease status of suspected individuals. If this is done, there would be more respite for those who would be eager to assess if they are indeed protected after vaccination. In order to ensure attainment of high seroconversion and seroprotection rate of the deployed vaccines so as to minimize the need for the assessment of individual security against the disease, the following suggestions are made: Governments should mount a country-wide Phase-IV trial with adequate placebo-controls to assess the efficacy of the deployed vaccines in the following interval regimen: Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 5
ACADEMIA Letters Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines Prasanta Ghosh Abstract As of March 31, 2021, eight vaccines against COVID-19 flu were approved globally, which include ChAdOx1 (AZS1222) [AstraZeneca/Oxford, UK]; COVAXIN [Bharat Biotech, India]; BNT162b2 [Pfizer-BioNTech, USA]; mRNA-1273 [Moderna, USA]; ADENO 26 CoV2.S [Johnson &Johnson, USA ]; and Sputnik V [Gamaleya Research Institute of Epidemiology and Microbiology, Moscow, Russia]. All are 2- dose vaccines except ADENO 26 CoV2.S, which requires one dose only. As there is yet no effective therapeutic substance to contain the disease, mass vaccination is the only effective alternative to fight the pandemic. Due to the non-availability of an adequate supply of vaccines, countries are resorting to delaying the use of the second dose, which must be deployed before the antibody titer is waned off after the first dose. There is a need to experimentally determine how much delay can be made between the 2 doses. Further, as people over 60y are more vulnerable to the disease, data need to be generated for each vaccine on this population on whether there is any need to reschedule the dosage gaps as also if 3 dose regimens are more efficacious. Keywords: COVID-19 vaccines, approved SARS-CoV-2 vaccines, vaccination efficacy Introduction The Regulatory authorities the world over have approved [1,2] the emergency use of the eight SARS-CoV-2 vaccines as of March-end, 2021 to protect the population from COVID19 flu. The approved vaccines are (1) ChAdOx1 (AZS1222) AstraZeneca/Oxford (UK)invented, Chimpanzee adenoviral vector-based replication-deficient viral vector containing Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 1 the c DNA based expression cassette coding for the SARS-CoV-2 S protein, and the vaccine is known as COVISHIELD requiring 2 doses, 28 days apart; (2) Bharat Biotech’s use of propiolactone-deactivated whole-virion SARS-CoV-2 strain named as NIV-2020-770, which is multiplied in Vero cells. The vaccine is named as COVAXIN by Bharat Biotech and requires 2 doses, 28 days apart for protection. The company has changed the name of the viral strain to BBV152. (3) Sinovac Biotech, China using deactivated whole-virion SARS-CoV-2 strain named as CN02 and multiplied in Vero cells and the vaccine is named as CORONA VAC, requiring 2 doses, 14 days apart; (4) Sinopharm, China using deactivated whole-virion SARS-CoV-2 strain named as HBO2 and multiplied in Vero cells, and the name of the vaccine is BBIBP-Cor V requiring 2 doses, 21 days apart; (5) Pfizer-BioNTech, USA manufacturing lab-synthesized mRNA coding for full-length S protein with proline substitutions, captured inside nano-particles using multiple amphiphilic substances and requiring 2 doses, 21 days apart; the vaccine is named as BNT162b2;(6) Moderna, USA manufacturing labsynthesized mRNA coding for full-length S protein with proline substitutions, captured inside nano-particles using multiple amphiphilic substances and requiring 2 doses, 14 days apart and named as mRNA-1273. The synthesized mRNA, as well as the amphiphilic substances used by Moderna, are different from those of Pfizer;( 7) Johnson &Johnson , USA manufacturing recombinant replication-deficient human adenovirus serotype 26-vector based DNA cassette containing the c DNA-based coding sequence for stabilized full-length SARS-CoV-2 S protein and the name of the vaccine is ADENO 26 CoV2.S , requiring application of two doses 28 days apart, and (8) the two-Adenoviral vector-based r DNA vaccine , using adenovirus type 26 having an insertion of c DNA- based nucleotide sequence coding for the full-length spike protein of SARS-CoV-2 virus ( Ad26) and the adenovirus type 5 , also having an insertion of c DNA- based nucleotide sequence coding for the full-length spike protein of the virus( Ad5). Both the adenoviruses are replication-incompetent. The combo vaccines were invented by the Gamaleya Research Institute of Epidemiology and Microbiology, Moscow. The vaccine initially named as Gam-COVID-Vac was renamed as Sputnik V is required in two doses, 21 days apart. Three of these namely (2), (3),(4) are whole-virion inactivated vaccines; threearerecombinant Adenoviral DNA-base replication-deficient DNA vaccines as at (1),(7), and (8); and two are m-RNA based, nano-particle encapsulated SARS-Co V -2 vaccines as ay (5) and (6). It is not easy to contemplate which ones are the most efficacious ones, which ones are comparatively safer, and which ones are the best ones for individuals. Two other types of injectable COVID-19 vaccines are in the pipeline which includes the use of attenuated SARSCoV-2 strain and the r-DNA derived viral spike protein-based vaccines. Besides, vaccines based on the newer delivery systems such as oral, nasal, skin-patch-based delivery are also under development [3]. Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 2 In the meantime, the COVID-19 flu continues to maintain its pandemic the world over. The world scenario on COVID-19 pandemic as of March 21, 2021, indicated[4] the total infected from the disease was 123,581,422; the total death was 2,724,071, and the total recovered was 99,552,14. India ranked third in terms of death, registering the number of deaths as 1,59,821 with total active cases of 1,16,05,673 and recovered cases of 1,11,32,082. The counties registering deaths more than India were the USA (554889 deaths) followed by Brazil (292856 deaths). World over patients with hypertension, diabetes, coronary heart disease, cerebrovascular illness, chronic obstructive pulmonary disease, and kidney dysfunction have worse clinical outcomes[5] when infected with SARS-CoV-2. There is yet no effective therapeutic substance to contain the disease. Mass vaccination is the only effective alternative to fight the disease. The immediate need is therefore to increase the herd immunity of every community and therefore all eligible individuals must be vaccinated. This is a stupendous task. The aim of the paper is to ascertain how fast the eligible world population in the senior age group above 60y be protected by vaccination; what is an experimentally determined time gap between the 2-dose vaccines; and what are the deciding parameters to ensure the protection of individuals above 60y from the disease. This age group of population is more vulnerable to the disease. Methodology The study was carried out based a table study of relevant literature accessed through the internet by using the Google search engine. The issues All the approved vaccines have been rated as reasonably safe for deployment. The efficacy of each one is, however, considerably different as had been determined from various studies, which has varied [6-10] from over 50% to over 90%. The mRNA vaccines have provided the highest percentage of protection among the recipients, above 90% while the other types provided much lesser protection.. There is no information on what is the protection rate in individuals above 60y of age for each type of vaccine. The mRNA vaccines are highly priced by the owners/suppliers; these are IPR protected and the prices are dictated by the owners. The other ones are moderately priced. Presently, the supply is inadequate and the available production is purchased by the governments; but sooner vaccines would be available in private markets also when more vaccines are approved and supply from the existing and new Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 3 manufacturers increase. Government vaccination programs are aimed at increasing the herd immunity of the community. Any vaccine that is more than 50% efficacious can contribute to raising the herd immunity of the population and governments can fight the pandemic using such vaccines. However, a vaccine with just above 50% efficacy shall take more time to raise the herd immunity than the one that imparts more than 90% efficacy as increased efficacy will contribute to reducing infection among the vaccinated population. Data published from Israel had shown [11] that even when about 90% of people aged 60y and older in the country had received the first dose of Pfizer’s 2-dose vaccine, there was a 41% drop in confirmed COVID-19 infections in that age group. The situation must have improved further after 2 doses were received. While the drop in the newer infection rate is the aim of government programs, senior citizens individually could be curious to ascertain if they have been protected after receiving an approved vaccine in the scheduled doses. Individual protection is important to individuals. There is yet no fool-proof method to ascertain this. Evaluation of the levels of clonal IgM/IgG to the nucleocapsid protein of the SARS-CoV-2 virus is indicative of whether there was an exposure to the virus. Methods for measuring the levels of neutralizing immunoglobulins in the vaccinated individuals against the spike protein of the virus are in place to ascertain if protection is imparted. The development of neutralizing antibodies (nAbs) to the spike protein, especially the receptor-binding domain (RBD) of the virus is the aim of vaccine–induced protective immunity. In a study[12] involving 19860 individuals recovered from COVID-19 flu, the measurement of total antibodies had shown that the about 70% of the individuals had moderate(1:320) to high(1:2880) titers and that over 90% of this population had neutralizing antibodies, specific to spike-proteins of the virus. Among the nAbs formed, which include IgG, IgE, IgM, and IgA, there has been a preponderance[13] of IgA antibodies which may play a dominant role in the control of infection. It can be apprehended therefore that measurement of the levels of circulating neutralizing antibodies of IgA types against the virus might provide a respite to ensuring protection. However, there is yet no well-defined, unanimous, globally accepted, foolproof method of determining whether, after vaccination, individuals have been protected. This information is important and more relevant for the aged individuals who are more than 60y in age. Due to the non-availability of an adequate supply of vaccines, countries are resorting to delaying the use of the second dose. Such delays under the circumstances may be justified provided the second dose is applied within a period when the neutralizing antibody titer emanating from the first dose is not waned off significantly. This change in the re-scheduling may be for bringing in more eligible people within the preview of the first dose so as to increase the number of the protected populations against the disease. The French National Academy of Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 4 Medicine in a press release[14]on Jan11, 2021had recommended a delay between two doses up to 3 weeks. However for this, experimental national and international data need to be generated for each type of vaccine deployed. Theoretically, delaying between the vaccine doses is scientifically improper. There is another complex issue that has surfaced over time from the multiple COVID19 infections. The original[15]SARS-CoV-2 virus has mutated and the mutated strains are developing capacities to evade the vaccine efficacy. The extent of evasion-from-capture by the immune system of the sensitized and immunized individuals is variable and differs from vaccines to vaccines. However, for a given vaccine type, it is anticipated to be in close range in a population. Multiple mutated viral SARS-CoV-2 strains are in circulation[16]in the human population of which some could pose a serious COVID-19 disease risk. Discussion and concluding remarks It is necessary to understand the dynamics of immune cells which are responsible for developing acquired immunity on being exposed to the SARS-CoV-2 virus or an antigen derived from the virus such as the vaccines. The measurement of the activated CD4+T-cells, cytotoxic CD8+ T-cells and the memory B- cells over a period of time after infection would provide insight into the persistence of the magnitude of adaptive immune response and can assist the assessment of the duration of immunity against another infection. Vaccines can also be assessed in the above way to assess their protective potential. In a recent study [17] using human subjects infected with the virus, the dynamics of the above immune cells were studied. It was found that about 95% of the subjects could maintain immune memory at about six months after infection. Interestingly, the circulating antibodies against the SARS-Co V-2 did not correlate with the T-cell memory. Assessment of the protective immunity against the virus has therefore to be carried out by the measurement of the preponderance of the residual T- memory cells, CD4+ T-cells, and CD8+T-cells. Therefore, a set of step-by-step instructions and standard operating procedures (SOPs) are to be evolved as has been done for assessing the COVID-19 disease status of suspected individuals. If this is done, there would be more respite for those who would be eager to assess if they are indeed protected after vaccination. In order to ensure attainment of high seroconversion and seroprotection rate of the deployed vaccines so as to minimize the need for the assessment of individual security against the disease, the following suggestions are made: Governments should mount a country-wide Phase-IV trial with adequate placebo-controls to assess the efficacy of the deployed vaccines in the following interval regimen: Academia Letters, July 2021 ©2021 by the author — Open Access — Distributed under CC BY 4.0 Corresponding Author: Prasanta Ghosh, gprasanta2008@gmail.com Citation: Ghosh, P. (2021). Generation of efficacy data on 60y and older population using SARS-CoV-2 Vaccines. Academia Letters, Article 1940. https://doi.org/10.20935/AL1940. 5