Vaccination is one of the most effective methods for preventing morbidity and mortality from COVID-19. Vaccine hesitancy has led to a decrease in vaccine uptake; driven by misinformation, fear, and perceptions of vaccine safety. Whole inactivated vaccines have been used in one-fifth of the vaccine recipients in Africa, however there is limited real-world data on their safety. We evaluated the reported side effects and factors associated with reported side effects following vaccination with whole inactivated COVID-19 vaccines - BBiBP-CorV (Sinopharm) and CoronaVac (Sinovac). A quantitative survey evaluating attitudes and side effects from vaccination was administered to 1016 adults presenting at vaccination centers. Two follow-up telephone interviews were conducted to determine side effects after the first and second vaccination dose. Overall, the vaccine was well tolerated; 26.0% and 14.4% reported side effects after the first and second dose respectively. The most frequent local and systemic side effects were pain at the injection site and headaches respectively. Most symptoms were mild, and no participants re-quired hospitalization. Participants who perceived COVID-19 vaccines as safe or had a personal COVID-19 experience were significantly less likely to report side effects. Our findings provide data on the safety and tolerability of whole inactivated COVID-19 vaccines in an African population, providing the necessary data to create effective strategies to increase vaccination and support vaccination campaigns.

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.

Several vaccines against COVID -19 have been developed and licenced to enhance the immune response against SARS-CoV-2. Similarly, infection with SARS-CoV-2 before vaccination has been shown to provide significant protection against severe infection and hospitalisation. The aim of this study was to investigate the effect of three doses of Sinopharm vaccine and SARS-CoV-2 infection on the specific immune response in 103 volunteers, measuring neutralizing antibodies, anti-S1 IgG, anti-RBD IgM, anti-N IgM, anti-N IgG antibodies and interferon γ. Our results showed that the presence of cardiovascular diseases increased the level of anti-N-IgG antibodies, while endocrinological diseases decreased the level of neutralizing antibodies and anti-N-IgG antibodies, suggesting that these diseases alter the effect of vaccine immunity. In addition, there was a significant decrease in anti-S1 IgG levels 6 months and in anti-N IgG levels 18 months post-infection, while neutralizing antibody and interferon γ levels were constant at 3, 6 and 18 months post-infection. Therefore, our results confirm the importance of hybrid immunity as the strongest and most durable compared to exclusively natural or vaccine-induced immunity. Significant positive correlations were found between humoral and cellular immunity markers: neutralizing antibodies, anti-S1 IgG, anti-N IgG and interferon γ, indicating a unique coordinated response specific to COVID-19.