Vaccination against the SARS-CoV2 virus has shown great promise in managing the spread and severity of Covid-19. While these vaccines were able to provide a favourable response in controlling the SARS-CoV2 infection, its use came with accompanying side effects. This systematic review aimed to determine the effectiveness of the different Covid-19 vaccine subtypes and discover the side effects associated with each vaccine elsewhere but specially in Trinidad and Tobago. For this systematic review, the keywords “Pfizer-BioNTech OR Moderna OR Oxford-AstraZeneca OR Janssen OR Sinopharm OR Novavax AND Covid-19 vaccine efficacy” and “Covid-19 vaccines AND Trinidad and Tobago” were researched under PubMed, MEDLINE and other internet sources through which other notable journals, and documents were discovered and searched similarly as outlined previously. In doing so, 65 relevant articles were included as part of this review. Of the studies examined, overall the vaccine with the greatest VE was found to be Pfizer-BioNTech (95%), followed by Moderna (94.1%), Novavax (89.7%), AstraZeneca (70.4%), Sinopharm (67%) and finally Janssen (66.9%). The use of Pfizer-BioNTech or Moderna was most efficacious in response to the different Covid-19 variants. Some side effects were common for all vaccine types however adverse effects were more commonly seen with vaccination by mRNA vaccines, Pfizer-BioNTech and Oxford-Astrazeneca. Researchers targeted individuals aged 18 and above residing in various geographical areas of TT, specifically focusing on those who had not received the COVID-19 vaccine and expressed hesitancy towards it. Convenience sampling was used to select the study participants, and formal in-depth virtual interviews were conducted on a one-to-one basis, employing a semi-structured questionnaire to guide the discussions. The interviews were meticulously recorded and transcribed, following the principles of reflexive thematic analysis, to distill key insights from the participants' responses. The study's findings, derived from the perspectives of 25 participants, illuminated a complex tapestry of reasons underlying vaccine hesitancy in Trinidad and Tobago. Notably, prominent themes emerged, including fear, doubts regarding vaccine efficacy, a perceived inadequacy of information, a sense of susceptibility to the virus, deep-seated mistrust, alternative herbal remedies, and religious reservations. Interestingly, the motivations expressed by these vaccine-hesitant individuals for potentially receiving the vaccine in the future were rooted in notions of necessity, an increased sense of susceptibility to the virus, a desire to reach a certain health benchmark, and a need for assurance regarding the vaccine's safety and effectiveness. This comprehensive exploration of vaccine hesitancy in TT provides valuable insights for public health officials and policymakers in crafting targeted strategies to address this critical issue within the local context. Conclusion: The findings of this study determined that vaccination against the SARS-CoV2 virus provided beneficial outcomes against infection, Covid-19 related hospitalizations, ICU admissions and mortality. While vaccination was deemed highly appropriate in managing the spread of the SARS-CoV2 virus and enhancing the outcomes in infected persons, the effectiveness of the different vaccine platforms indicated that certain vaccine platforms are preferential to others in different populations. In terms of vaccine efficacy, nucleic acid vaccines such as Pfizer-BioNTech and Moderna showed the greatest effectiveness while inactivated whole virus vaccines such as Sinopharm and viral vectors like Janssen had the least effectiveness. The side effects, joint/muscle soreness, pain at the injection site, shoulder pain, headaches, fever, chills, weakness, epistaxis, renal and certain cardiovascular events were common for all vaccine types. Adverse effects were more frequent and severe with the mRNA vaccines by Pfizer-BioNTech and Oxford-Astrazeneca than inactivated whole virus vaccines. The data collected in this research can be very useful to help individuals make a decision on which vaccine would be appropriate for them. More long-term studies are needed to better gauge the scope of side effects for each vaccine type.

The study evaluated the immune response to the Janssen Ad26.COV2.S COVID-19 vaccine in a Ugandan cohort, focusing on spike (S) and nucleocapsid (N) protein-directed antibodies. The aim was to assess the longevity and robustness of the elicited antibodies, aligning with breakthrough infections and prior exposure to SARS-CoV-2. The study involved 319 specimens collected over 12 months from 60 vaccinees aged 18 to 64. Binding antibodies were quantified using a validated ELISA method to measure SARS-CoV-2-specific IgG, IgM, and IgA levels against the S and N proteins. The results showed that baseline seropositivity for S-IgG was high at 67%, increasing to 98% by day 14 and consistently stayed above 95% for up to 12 months. However, S-IgM responses remained suboptimal. An increased S-IgA serpositivity rate doubled from 40% at baseline to 86% just two weeks following the initial vaccine dose, indicating sustained and robust mucosal immunity. An increase in N-IgG levels at nine months post-vaccination suggested breakthrough infections in eight cases. Baseline cross-reactivity influenced spike-directed antibody responses, with those with pre-existing S-IgG antibodies showing higher responses. The vaccine demonstrated robust and long-lasting immune responses, with significant implications for regions where administering follow-up doses is challenging.