The spectrum of side effects associated with COVID-19 vaccines in patients with inborn errors of immunity.

OBJECTIVE: COVID-19 immunization was implemented with emergency-use authorization. We had concerns/lack of information on mRNA vaccine side effects in different inborn errors of immunity (IEI) types. METHODS: We enrolled 141 patients (IEIP) and 151 healthy controls(HC) who received SARS-CoV-2 vaccine/s(Sinovac and/or Pfizer-BioNTech(mRNA vaccine), one to five doses), questioned them for side-effects, evaluated in three groups according to the vaccine/s they received; only Sinovac, only Pfizer-BioNTech, and both vaccines. RESULTS: Arm pain, generalized weakness, myalgia, and fever were common side effects in IEI-P and HC groups. Generalized weakness/fatigue, fever, and palpitation were significantly frequent in IEI-P who experienced COVID-19 compared to those who did not (p = 0.021, p = 0.047, and p = 0.024, respectively). Severe symptoms after vaccination, new-onset splenomegaly and pancytopenia, urticaria, herpes simplex virus (HSV), and varicella zoster virus (VZV) reactivation were seen in four IEI-P (2.8%). CONCLUSION: IEI-P mRNA vaccination is relatively safe compared to the conventional vaccine. Individuals who experience uncommon side effects should undergo immunological screening.

Safety and immunogenicity of homologous prime-boost CoronaVac vaccine in people living with HIV in China: A multicenter prospective cohort study.

People living with HIV (PLWH) are particularly vulnerable to SARS-CoV-2. This multicentre prospective cohort study evaluated the long-term immunogenicity and safety of a third homologous dose of Sinovac CoronaVac in PLWH in China. A total of 228 PLWH and 127 HIV-negative controls were finally included and followed up for 6 months. Fewer participants reported mild or moderate adverse reactions, and no serious adverse events were observed. The median levels of neutralizing antibodies (nAbs) and immunoglobulin G against the receptor-binding domain of the spike protein (S-IgG) in PLWH (655.92 IU/mL, IQR: 175.76-1663.55; 206.83 IU/mL, IQR: 85.20-397.82) were comparable to those in control group (1067.16 IU/mL, IQR: 239.85-1670.83; 261.70 IU/mL, IQR: 77.13-400.75), and reached their peak at 4 weeks, exhibiting a delayed peak pattern compared to the 2-week peak in control group. After then, the immune titres gradually decreased over time, but most participants still maintained positive seroconversion at the 6-month mark. Multivariable generalized estimating equation analysis indicated that CD4+T cell count, HIV viral load, and antiretroviral therapy (ART) were independent factors strongly associated with immune response (each p < 0.05). We suggested that PLWH should maintain well-controlled HIV status through ART and receive timely administration of the second booster dose for optimal protection.

Metabolic Adaptations Correlated with Antibody Response after Immunization with Inactivated SARS-CoV-2 in Brazilian Subjects.

The adsorbed vaccine SARS-CoV-2 (inactivated) produced by Sinovac (SV) was the first vaccine against COVID-19 to be used in Brazil. To understand the metabolic effects of SV in Brazilian subjects, NMR-based metabolomics was used, and the immune response was studied in Brazilian subjects. Forty adults without (group-, n = 23) and with previous COVID-19 infection (group+, n = 17) were followed-up for 90 days postcompletion of the vaccine regimen. After 90 days, our results showed that subjects had increased levels of lipoproteins, lipids, and N-acetylation of glycoproteins (NAG) as well as decreased levels of amino acids, lactate, citrate, and 3-hydroxypropionate. NAG and threonine were the highest correlated metabolites with N and S proteins, and neutralizing Ab levels. This study sheds light on the immunometabolism associated with the use of SV in Brazilian subjects from Rio de Janeiro and identifies potential metabolic markers associated with the immune status.

Hypersensitivity reactions to COVID-19 vaccines: a case of Eosinophilic pneumonia following Sinovac/CoronaVac vaccination.

Summary: Hypersensitivity reactions has been reported with COVID-19 vaccines. Acute eosinophilic pneumonia has not been reported yet after Sinovac/CoronaVac vaccine. A 73-year-old woman presented with maculopapular rash, cough and dyspnea following Sinovac/CoronaVac injection. The complete blood count (CBC) indicated eosinophilia and further evaluation of the eosinophilia with CT and bronchoscopy confirmed a diagnosis of acute eosinophilic pneumonia. After methylprednisolone therapy, her rash resolved with marked improvement of the dyspnea. She is still on treatment and on the follow up period, we plan to continue steroid treatment at least 3 months.

Efficacy of antibody response following the vaccination of SARS-CoV-2 infected and noninfected healthcare workers by two-dose inactive vaccine against COVID-19.

Sinovac is an inactive vaccine produced against Coronavirus Disease 2019 (COVID-19) for almost a year. No sufficient information is available concerning pro-vaccine immunogenicity. We investigated the efficacy of antibody response following vaccination of SARS-CoV-2-infected and noninfected healthcare workers by a two-dose inactive vaccine against COVID-19. The immunogenicity acquired on the 27th day and 42nd day after the first dose of vaccine (corresponding to Day 14 after the second dose) were compared by the demographics, immunosuppression, comorbidities, postvaccination reaction, and IgG levels of 120 subjects. The overall rate of second postvaccine seropositivity was 97.5% (n = 117) of all individuals, and 44 of these were seropositive after the first dose. The percentage of having a previous COVID-19 (59.1%) among seropositive individuals before 2nd vaccination was significantly higher than those of seropositive individuals (10.96%) after second vaccination (p < 0.0001). In our study, 35 healthcare workers stated that they had previously had a COVID-19 infection. Anti-SARS-CoV-2 antibody responses in people infected with SARS-CoV-2 follow a classical pattern, with a rapid increase within the first 3 weeks after the appearance of symptoms. Although the titers decreased thereafter, the ability to detect anti-SARS-CoV-2 IgG antibodies supports the view that the majority of subjects previously screened as positive for virus remain intact with confirmed neutralizing activity for up to 6 months.

Evaluation of antibody response after two doses of the Sinovac vaccine and the potential need for booster doses in cancer patients.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is more severe in some specific patient groups, such as cancer patients with a mortality rate of 26.5%. The main way of protection is vaccination. In this study, we aimed to evaluate the antibody responses of our cancer patients who received two doses of the inactivated COVID-19 vaccine manufactured by Sinovac Life Sciences. Patients over the age of 18, who had not been suspected or polymerase chain reaction-confirmed COVID-19 positive, who received two doses of the vaccine, and at least 28 days passed after the second dose, and who received at least one dose of cancer treatment before the vaccination-were included in the study. Immunoglobulin class G antibodies against the receptor binding region (S-RBD) of the spike protein S1 subunit of SARS-CoV-2 were studied. A total of 200 patients with a diagnosis of cancer were included in the study. The median time between the second dose of the Sinovac vaccine and the time of blood collection was 3.44 (3.20-3.84) months. SARS-CoV-2 antibody positivity was detected in 110 (55%) patients. The two subgroups with the highest antibody levels were gynecological cancers and breast cancers, with median 158.5 AU/ml (38.4-764.5) and 106.3 AU/ml (61.9-162.9) levels, respectively. Antibody positivity rate was 46.8% in patients who received chemotherapy at any time between the first dose of the vaccine and the date of blood collection; and it was 73.8% in the group that did not receive chemotherapy (p < 0.001). As a result, the expected antibody response was not obtained with two doses of the Sinovac vaccine. Therefore, if the Sinovac vaccine is to be preferred for these patients, the appropriate booster time for the third dose should be determined or other vaccines, such as messenger RNA vaccines, with reported higher antibody responses should be considered.

Vaccines for Covid-19: An insight on their effectiveness and adverse effects.

An era of SARS-COVID-19 outbreak with a high contagious percentage around the globe has been the subject of multi-agency research aimed at generating vaccines for active immunization. Scientists across the world are joining hands for advanced tie-ups between medical start-ups and pharmaceutical industries for devices and vaccines development to hinder the progress of this outbreak. Moreover, the questions that need to be answered are how to improve the effectiveness and efficacy of vaccines with reduced side effects and the required doses of vaccines for enhanced surveillance. In this review article, we have discussed the effectiveness and efficacy of different Covid-19 vaccines.

CoronaVac/Sinovac COVID-19 Vaccine-Related Hypersensitivity Reactions and Second-Dose Vaccine Administration: Tertiary Allergy Center Experience.

INTRODUCTION: The COVID-19 pandemic has caused a global health crisis. To prevent the disease, the Ministry of Health of Turkey gained approval for the CoronaVac COVID-19 vaccine for emergency use as the first-line. This study aimed to evaluate patients who developed hypersensitivity reactions (HRs) due to the CoronoVac vaccine and to share our experience of administering the second dose of vaccine to these patients. METHODS: The study group included the patients who presented to the Ege University Allergy and Immunology Division between January and May 2021. Demographic data, atopic status, allergic reactions to the first dose of the COVID-19 vaccine and the route of second-dose vaccine administrations were recorded. RESULTS: A total of 7 patients (four healthcare professionals), 6 (86%) of whom were women, with an average age of 53.4 years, were included in the study. The rate of allergic reactions among Ege University health workers was 0.036% (2/5,558). Six of our patients had a history of additional allergic diseases and comorbid diseases. None had any allergic reactions to previous vaccinations and latex allergy. Reactions developed commonly on the skin, as generalized urticaria/angioedema and pruritus. The severity of the reactions was evaluated as mild in 2, moderate in 3, and severe in 2 cases. The second-dose CoronaVac was safely administered by using a gradually increase dose in a total of 6 patients. CONCLUSION: In patients with HRs due to Sinovac in the first dose, the second dose can be safely performed using a gradually increased dose.

COVID-19: vaccination vs. hospitalization.

OBJECTIVE: Vaccination is the most efficient way to control the coronavirus disease 2019 (COVID-19) pandemic, but vaccination rates remain below the target level in most countries. This multicenter study aimed to evaluate the vaccination status of hospitalized patients and compare two different booster vaccine protocols. SETTING: Inoculation in Turkey began in mid-January 2021. Sinovac was the only available vaccine until April 2021, when BioNTech was added. At the beginning of July 2021, the government offered a third booster dose to healthcare workers and people aged > 50 years who had received the two doses of Sinovac. Of the participants who received a booster, most chose BioNTech as the third dose. METHODS: We collected data from 25 hospitals in 16 cities. Patients hospitalized between August 1 and 10, 2021, were included and categorized into eight groups according to their vaccination status. RESULTS: We identified 1401 patients, of which 529 (37.7%) were admitted to intensive care units. Nearly half (47.8%) of the patients were not vaccinated, and those with two doses of Sinovac formed the second largest group (32.9%). Hospitalizations were lower in the group which received 2 doses of Sinovac and a booster dose of BioNTech than in the group which received 3 doses of Sinovac. CONCLUSION: Effective vaccinations decreased COVID-19-related hospitalizations. The efficacy after two doses of Sinovac may decrease over time; however, it may be enhanced by adding a booster dose. Moreover, unvaccinated patients may be persuaded to undergo vaccination.

Effectiveness of inactivated SARS-CoV-2 vaccine (CoronaVac) on intensive care unit survival.

This study compared the course of coronavirus disease 2019 (COVID-19) in vaccinated and unvaccinated patients admitted to an intensive care unit (ICU) and evaluated the effect of vaccination with CoronaVac on admission to ICU. Patients admitted to ICU due to COVID-19 between 1 April 2021 and 15 May 2021 were enrolled to the study. Clinical, laboratory, radiological parameters, hospital and ICU mortality were compared between vaccinated patients and eligible but unvaccinated patients. Patients over 65 years old were the target population of the study due to the national vaccination schedule. Data from 90 patients were evaluated. Of these, 36 (40.0%) were vaccinated. All patients had the CoronaVac vaccine. Lactate dehydrogenase and ferritin levels were higher in an unvaccinated group than vaccinated group (P = 0.021 and 0.008, respectively). SpO2 from the first arterial blood gas at ICU was 83.71 ± 19.50% in vaccinated, 92.36 ± 6.59% in unvaccinated patients (P = 0.003). Length of ICU and hospital stay were not different (P = 0.204, 0.092, respectively). ICU and hospital mortality were similar between groups (P = 0.11 and 0.70, respectively). CoronaVac vaccine had no effect on survival from COVID-19. CoronaVac's protective effect, especially on new genetic variants, should be investigated further.

A systematic review on mucocutaneous presentations after COVID-19 vaccination and expert recommendations about vaccination of important immune-mediated dermatologic disorders.

With dermatologic side effects being fairly prevalent following vaccination against COVID-19, and the multitude of studies aiming to report and analyze these adverse events, the need for an extensive investigation on previous studies seemed urgent, in order to provide a thorough body of information about these post-COVID-19 immunization mucocutaneous reactions. To achieve this goal, a comprehensive electronic search was performed through the international databases including Medline (PubMed), Scopus, Cochrane, Web of science, and Google scholar on July 12, 2021, and all articles regarding mucocutaneous manifestations and considerations after COVID-19 vaccine administration were retrieved using the following keywords: COVID-19 vaccine, dermatology considerations and mucocutaneous manifestations. A total of 917 records were retrieved and a final number of 180 articles were included in data extraction. Mild, moderate, severe and potentially life-threatening adverse events have been reported following immunization with COVID vaccines, through case reports, case series, observational studies, randomized clinical trials, and further recommendations and consensus position papers regarding vaccination. In this systematic review, we categorized these results in detail into five elaborate tables, making what we believe to be an extensively informative, unprecedented set of data on this topic. Based on our findings, in the viewpoint of the pros and cons of vaccination, mucocutaneous adverse events were mostly non-significant, self-limiting reactions, and for the more uncommon moderate to severe reactions, guidelines and consensus position papers could be of great importance to provide those at higher risks and those with specific worries of flare-ups or inefficient immunization, with sufficient recommendations to safely schedule their vaccine doses, or avoid vaccination if they have the discussed contra-indications.

Antibody response with SARS-CoV-2 inactivated vaccine (CoronaVac) in Turkish geriatric population.

BACKGROUND: Sars-CoV-2 infection influences older individuals at the forefront, and there is still limited data on the COVID-19 vaccine response in the geriatric population. This study aimed to assess antibody response after vaccination with SARS-CoV-2 inactivated vaccine and examine possible factors affecting this response in a geriatric population. METHODS: individuals who have been on at least the 28th day after the second dose of the COVID-19 vaccine were included. Comprehensive geriatric assessment tools and the Clinical Frailty Scale were performed. SARS-CoV-2 spike-specific IgG antibodies were detected and, levels ≥1 U/ml were defined as seropositive, <1 U/ml were defined as seronegative. RESULTS: a total of 497 patients were included and divided into three groups according to the days past after the second dose of the vaccine (Group 1: 28-59 days, Group 2: 60-89 days and Group 3: 90 days and more). Groups included 188, 148 and 171 patients, respectively. Seropositivity rate in each group was 80.9,73.2 and 57.3%, respectively. In Groups 1 and 2, Charlson Comorbidity Index score was higher in the seronegative group (P = 0.023 and P = 0.011, respectively). In Group 3, the prevalence of frailty was significantly higher in the seronegative group (P = 0.002). CONCLUSION: to the best of our knowledge, this is the first study assessing the antibody response after vaccination with Sars-CoV 2 inactivated vaccine in the Turkish geriatric population. Moreover, this is the first study revealing the relationship between antibody response and frailty. Larger studies are needed to confirm the antibody response duration and the association between frailty and COVID-19 vaccine response.

Comparison of the immunogenicity of BNT162b2 and CoronaVac COVID-19 vaccines in Hong Kong.

BACKGROUND AND OBJECTIVE: Few head-to-head evaluations of immune responses to different vaccines have been reported. METHODS: Surrogate virus neutralization test (sVNT) antibody levels of adults receiving either two doses of BNT162b2 (n = 366) or CoronaVac (n = 360) vaccines in Hong Kong were determined. An age-matched subgroup (BNT162b2 [n = 49] vs. CoronaVac [n = 49]) was tested for plaque reduction neutralization (PRNT) and spike-binding antibody and T-cell reactivity in peripheral blood mononuclear cells. RESULTS: One month after the second dose of vaccine, BNT162b2 elicited significantly higher PRNT50 , PRNT90 , sVNT, spike receptor binding, spike N-terminal domain binding, spike S2 domain binding, spike FcR binding and antibody avidity levels than CoronaVac. The geometric mean PRNT50 titres in those vaccinated with BNT162b2 and CoronaVac vaccines were 251.6 and 69.45, while PRNT90 titres were 98.91 and 16.57, respectively. All of those vaccinated with BNT162b2 and 45 (91.8%) of 49 vaccinated with CoronaVac achieved the 50% protection threshold for PRNT90. Allowing for an expected seven-fold waning of antibody titres over 6 months for those receiving CoronaVac, only 16.3% would meet the 50% protection threshold versus 79.6% of BNT162b2 vaccinees. Age was negatively correlated with PRNT90 antibody titres. Both vaccines induced SARS-CoV-2-specific CD4+ and CD8+ T-cell responses at 1 month post-vaccination but CoronaVac elicited significantly higher structural protein-specific CD4+ and CD8+ T-cell responses. CONCLUSION: Vaccination with BNT162b2 induces stronger humoral responses than CoronaVac. CoronaVac induces higher CD4+ and CD8+ T-cell responses to the structural protein than BNT162b2.

First Report of Cerebral Venous Thrombosis Following Inactivated-Virus Covid Vaccination (Sinopharm and Sinovac).

Cerebral venous thrombosis (CVT) is an uncommon cerebrovascular disease, which has been reported with covid infection as well as covid vaccines, particularly AstraZeneca and Janssen vaccines. We present four consecutive cases of CVT after receiving either Sinopharm or Sinovac vaccine, both of which are composed of an inactivated-virus. All the patients recovered well with anticoagulation and discharged with a good functional outcome. This is the first case series reporting CVT following the administration of these vaccines.

Prolonged migraine aura resembling ischemic stroke following CoronaVac vaccination: an extended case series.

BACKGROUND: After the initiation of the COVID-19 vaccination program in Thailand, thousands of patients have experienced unusual focal neurological symptoms. We report 8 patients with focal neurological symptoms after receiving inactivated virus vaccine, CoronaVac. CASE SERIES: Patients were aged 24-48 years and 75% were female. Acute onset of focal neurological symptoms occurred within the first 24 h after vaccination in 75% and between 1-7d in 25%. All presented with lateralized sensory deficits, motor deficits, or both, of 2-14 day duration. Migraine headache occurred in half of the patients. Magnetic resonance imaging of the brain during and after the attacks did not demonstrate any abnormalities suggesting ischemic stroke. All patients showed moderately large regions of hypoperfusion and concurrent smaller regions of hyperperfusion on SPECT imaging while symptomatic. None developed permanent deficits or structural brain injury. DISCUSSIONS: Here, we present a case series of transient focal neurological syndrome following Coronavac vaccination. The characteristic sensory symptoms, history of migraine, female predominant, and abnormal functional brain imaging without structural changes suggest migraine aura as pathophysiology. We propose that pain related to vaccine injection, component of vaccine, such as aluminum, or inflammation related to vaccination might trigger migraine aura in susceptible patients.

Determination of COVID-19 PCR positivity and mutation status in coronaVac vaccinated individuals in Turkey.

BACKGROUND: CoronaVac is an inactivated virus-based COVID-19 vaccine used in Turkey and approved for emergency use by the World Health Organization (WHO). In this study, it was aimed to retrospectively evaluate the mutation status and clinical status in individuals who received two doses of CoronaVac vaccine and were infected with COVID-19 at least two weeks after the second dose. METHODS: 164 people were included in the study and COVID-19 diagnosis and mutation analyses were determined by RT-PCR using the Bioseepdy SARS CoV-2 Double Gene RT-qPCR Kit and the Biospeedy SARS-CoV-2 Variant Plus kit in accordance with the protocol determined by the manufacturer. RESULTS: 116 (70.7%) UK (Alpha, B.1.1.7) mutation and 3 (1.8%) South Africa (Beta, B.1.351), Brazil (Gamma, P.1) mutations were determined in 164 double doses CoronaVac vaccinated patients; 45 (27.5%) patients were mutation negative. Nine patients (5.5%) developed pneumonia. Eight patients (4.9%) had CT findings compatible with corona virus infection. Seven (4.3%) of the patients received treatment in the intensive care unit, and 5 (3%) of the patients were intubated. DISCUSSION: In conclusion, people who receive two doses of CoronaVac vaccine can be reinfected with mutant viruses, vaccine significantly reduces the need for hospitalization, CT findings and intensive care.

Acute prolonged motor aura resembling ischemic stroke after COVID - 19 vaccination (CoronaVac): the first case report.

BACKGROUND: We report the first case of a patient who suffered transient focal neurological deficit mimicking stroke following CoronaVac vaccination. However, instead of an ischemic stroke, motor aura was suspected. CASE PRESENTATIONS: A 24 year-old Thai female presented with left hemiparesis fifteen minutes after receiving CoronaVac. She also had numbness of her left arm and legs, flashing lights, and headaches. On physical examination, her BMI was 32.8. Her vital signs were normal. She had moderate left hemiparesis (MRC grade III), numbness on her left face, arms, and legs. Her weakness continued for 5 days. A brain CT scan was done showing no evidence of acute infarction. Acute treatment with aspirin was given. MRI in conjunction with MRA was performed in which no restricted diffusion was seen. A SPECT was performed to evaluate the function of the brain showing significant hypoperfusion of the right hemisphere. The patient gradually improved and was discharged. DISCUSSIONS: In this study, we present the first case of stroke mimic after CoronaVac vaccination. After negative imaging studies had been performed repeatedly, we reach a conclusion that stroke is unlikely to be the cause. Presumably, this phenomenon could possibly have abnormal functional imaging study. Therefore, we believed that it might be due to cortical spreading depression, like migraine aura, which we had conducted a literature review.

Factors Associated with SARS-CoV-2 Antibody Titer After Sinovac Vaccination Among Health Care Workers.

BACKGROUND: One of the methods to record immunogenicity after vaccination is to measure antibody titer. This study aimed to get the value of antibody titer post Sinovac vaccination and to analyze factors that associate with it. The trend of titer changes within 3 months period and the incidence of COVID-19 were also observed. METHODS: A prospective cohort study was conducted in March until May 2021 involving 250 health care workers of Siloam Hospitals Lippo-Cikarang who have completed two doses of Sinovac vaccination. We collected 3 titer data from each participant to observe the trend of changes. The incidence of COVID-19 among post-vaccinated subjects was also calculated. RESULTS: From total of 250 participants, 88 (35.2%) were males and 162 (64.8%) were females. Fourteen days after vaccination, 248 subjects (99.2%) had seroconversion. The median antibody titer amounted to 63.58 U/ml (0.4->250 U/ml). The titer was higher in age group 26-39 years (85.1 U/ml, p=0.003) and in women (78.7 U/ml, p=0.007). Within 3 months period, 162 from 200 participants (81%) who completed 3 titer tests, had antibody titer reduction (p=0.231). In observation, 94 from 245 (38.3%) participants tested positive COVID-19, with only 5 out of 94 (5.3%) participants being hospitalized. CONCLUSION: The highest median titer was achieved 14 days after Sinovac vaccination (63.58 U/ml). Younger age group and women are associated with higher value. The reduction trend in titer within 3 months is insignificant. Among post-vaccinated infection subjects, the hospitalization rate is low, which shows that Sinovac vaccination still has a protective effect.

Evaluation of SARS-CoV-2 Antibody Levels in Pharmacists and Pharmacy Staff Following CoronaVac Vaccination.

Objectives: The aim of this study was to determine the seropositivity rate of pharmacists and pharmacy staff after the administration of two doses of the CoronaVac-SinoVac vaccine and to assess changes in their antibody levels according to sociodemographic characteristics. Materials and Methods: This descriptive study was conducted between June 04, 2021 and September 30, 2021 in pharmacies located in Istanbul, Türkiye. The results of self-initiated immunoglobulin (Ig) G testing of the pharmacists and pharmacy staff, conducted at diagnostic laboratories contracted by the Istanbul Chamber of Pharmacists, were obtained using an online data collection tool. IgG measurements taken from 15 days up to 120 days after the two vaccine doses were included in the study. Participants were asked whether they smoked, had any chronic diseases (hypertension, chronic obstructive pulmonary disease, asthma, diabetes, etc.), or took any medications. Subgroup analyses were performed for each method used to measure antibody levels. Results: The study included 329 pharmacists/pharmacy staff (298 pharmacists and 31 pharmacy staff). The mean age of the participants was 49.7 ± 13.7 years, and 71.4% were female. The antibody positivity of the 329 participants was 94.9% following the two doses. The positivity rate was 95.4% in participants under 65 years of age, whereas it was 91.8% in those aged 65 years and over. There was no significant difference in the mean age between those with positive and negative antibody results (p > 0.05). Although antibody levels were lower older people, smokers, and those with chronic diseases, this difference was not statistically significant (p > 0.05). Conclusion: Seropositivity developed following the administration of two doses of CoronaVac-Sinovac vaccines. IgG antibody levels were lower in older adults, smokers, and those with chronic diseases, although not to a statistically significant extent. Further studies are needed to better understand the reasons for the different immunological responses to COVID-19.

A Systematic Review of the COVID Vaccine's Impact on the Nervous System.

AIMS & OBJECTIVES: The objective of this study was to conduct a systematic review of research pertaining to the COVID-19 vaccine and its association with neurological complications. METHOD: We performed a comprehensive search of the literature using Google Scholar, PubMed, and NCBI databases from December 2021 to December 2022. For Google Scholar, PubMed, and NCBI databases we used the following key search terms: "neurological adverse effects", "COVID-19 vaccination", "SARS-CoV-2", CNS complications, and CNS adverse effects. Two reviewer authors individually searched and assessed the titles and abstracts of all articles. The third reviewer resolved the disagreement between them. Data were documented regarding title, study location, type of study, type of COVID-19 vaccine, type of neurological complications/adverse effects, and sample size. RESULTS: From our findings, it is confirmed that these neurological complications like GuillainBarre syndrome (23.6%), Neuromyelitis Optica spectrum disorder (5.5%), Neuropathy (6.9%), Transverse Myelitis (8.3%) and Acute disseminated Encephalomyelitis (4.1%) are majorly affected in most of the people. The increase in risks associated with SARS-CoV-2 infection far outweighs any previously reported associations with vaccination. CONCLUSION: We found no safety signal was observed between COVID-19 vaccines and the immune-mediated neurological events. Before assuming a causal relationship, the side effects of the COVID-19 vaccine should first be carefully examined to rule out known associated factors. Symptom onset was within two weeks of vaccination in the majority of cases; as such, this seems to be a high-risk period warranting vigilance.