The SARS-CoV-2 Omicron variant and its sublineages continue to cause COVID-19-associated pediatric hospitalizations, severe disease, and death globally. BNT162b2 and CoronaVac are the main vaccines used in Chile. Much less is known about the Wuhan-Hu-1 strain-based vaccines in the pediatric population compared to adults. Given the worldwide need for booster vaccinations to stimulate the immune response against new Omicron variants of SARS-CoV-2, we characterized the humoral and cellular immune response against Omicron variant BA.1 in a pediatric cohort aged 10 to 16 years who received heterologous vaccination based on two doses of CoronaVac, two doses of CoronaVac (2x) plus one booster dose of BNT162b2 [CoronaVac(2x) + BNT162b2 (1x)], two doses of CoronaVac plus two booster doses of BNT162b2 [CoronaVac(2x) + BNT162b2 (2x)], and three doses of BNT162b2. We observed that the [CoronaVac(2x) + BNT162b2 (2x)] vaccination showed higher anti-S1 and neutralizing antibody titers and CD4 and CD8 T cell immunity specific to the Omicron variant compared to immunization with two doses of CoronaVac alone. Furthermore, from all groups tested, immunity against Omicron was highest in individuals who received three doses of BNT162b2. We conclude that booster vaccination with BNT162b2, compared to two doses of CoronaVac alone, induces a greater protective immunity.

Herein, we report the case of a 69-year-old patient who presented to our dermatology clinic for a skin eruption characterized by grouped hemorrhagic vesicles and erosions covered by hemorrhagic crusts on an erythematous background located on the lower right limb. The lesions were small, clustered, and variable in size (diameters between one and 10 mm) and located at the level of the L4-L5 dermatomes. The rash had started three to five days after the complete COVID-19 vaccination scheme with the BNT162b2 Pfizer BioNTech vaccine and had been accompanied by a flu-like syndrome. The histopathological examination established the diagnosis of leukocytoclastic vasculitis potentially in the context of a cytopathic zoster phenomenon. The atypical aspect of the zosterian eruption required additional laboratory work-up to identify possible causes of immunosuppression, i.e., screening for the presence of the human immunodeficiency virus (HIV) infection, solid cancers, as well as measurement of serum immunoglobulin concentrations, which revealed that the subject was HIV-positive. Antiviral treatment was started, with a favorable evolution of the lesions, and the patient was referred to an infectious diseases clinic for initiation of antiretroviral therapy (ART).

Severe acute respiratory syndrome virus 2 (SARS-CoV-2) has caused over million deaths worldwide, with more than 61,000 deaths in Chile. The Chilean government has implemented a vaccination program against SARS-CoV-2, with over 17.7 million people receiving a complete vaccination scheme. The final target is 18 million individuals. The most common vaccines used in Chile are CoronaVac (Sinovac) and BNT162b2 (Pfizer-Biotech). Given the global need for vaccine boosters to combat the impact of emerging virus variants, studying the immune response to SARS-CoV-2 is crucial. In this study, we characterize the humoral immune response in inoculated volunteers from Chile who received vaccination schemes consisting of two doses of CoronaVac [CoronaVac (2x)], two doses of CoronaVac plus one dose of BNT162b2 [CoronaVac (2x) + BNT162b2 (1x)], and three doses of BNT162b2 [BNT162b2 (3x)].
We recruited 469 participants from Clínica Dávila in Santiago and the Health Center Víctor Manuel Fernández in the city of Concepción, Chile. Additionally, we included participants who had recovered from COVID-19 but were not vaccinated (RCN). We analyzed antibodies, including anti-N, anti-S1-RBD, and neutralizing antibodies against SARS-CoV-2.
We found that antibodies against the SARS-CoV-2 nucleoprotein were significantly higher in the CoronaVac (2x) and RCN groups compared to the CoronaVac (2x) + BNT162b2 (1x) or BNT162b2 (3x) groups. However, the CoronaVac (2x) + BNT162b2 (1x) and BNT162b2 (3x) groups exhibited a higher concentration of S1-RBD antibodies than the CoronaVac (2x) group and RCN group. There were no significant differences in S1-RBD antibody titers between the CoronaVac (2x) + BNT162b2 (1x) and BNT162b2 (3x) groups. Finally, the group immunized with BNT162b2 (3x) had higher levels of neutralizing antibodies compared to the RCN group, as well as the CoronaVac (2x) and CoronaVac (2x) + BNT162b2 (1x) groups.
These findings suggest that vaccination induces the secretion of antibodies against SARS-CoV-2, and a booster dose of BNT162b2 is necessary to generate a protective immune response. In the current state of the pandemic, these data support the Ministry of Health of the Government of Chile\'s decision to promote heterologous vaccination as they indicate that a significant portion of the Chilean population has neutralizing antibodies against SARS-CoV-2.

This retrospective observational study is aimed to determine the efficacy of BNT162b2 (Pfizer-BioNTech) and CoronaVac (Sinovac) vaccines against symptomatic or severe disease in COVID-19-diagnosed patients. The secondary aim was to define the differences between vaccinated and un-vaccinated patients in terms of age, comorbidities and course of the disease, and to determine the survival rates. Of the 1463 PCR-positive patients, 55.3 % were vaccinated, and 44.7 % were unvaccinated. While 959 patients had mild-moderate symptoms, 504 patients had severe-critical symptoms and were treated in the intensive care unit. There was a statistically significant difference in the distribution of the type and doses of vaccines between the patient groups (p = 0.021). The rate of receiving 2 doses of Biontech was 18.9 % in the mild-moderate patient group but lower in the severe patient group (12.6 %). The rate of two doses of Sinovac and two doses of Biontech vaccine (four doses of vaccine) was 5 % in the mild-moderate patient group and 1.9 % in the severe patient group. The mortality rates were statistically significantly different (p < 0.001) between the patient groups: 65.3 % in the severe patient group and 1 % in the mild-moderate patient group. The multivariate model showed that the mortality risk of the unvaccinated patients was 1.5 times higher than the vaccinated ones (p = 0.042). In addition to being unvaccinated, advanced age, coronary artery disease (CAD), diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), and obesity were found to be associated with higher mortality risk. Besides, the reduction in mortality rate was more evident in individuals vaccinated with at least 2 doses of the BNT162b2 (Pfizer-BioNTech) vaccine than in CoronaVac group.

The Coronavirus 2019 (COVID-19) pandemic has affected over 700 million people worldwide and caused nearly 7 million deaths. Vaccines currently developed or in development are the most effective tools for curbing the pandemic and mitigating its impacts. In Turkey, inoculation with the Pfizer-BioNTech COVID-19 vaccine (BNT162b2, also known as tozinameran) has been approved. We report a 56-year-old female patient with underlying essential hypertension who experienced intracranial hemorrhage after receiving her first dose of tozinameran. The patient underwent immediate surgical evacuation of the hematoma, during which a left middle cerebral artery bifurcation aneurysm was macroscopically identified and clipped. The patient was pronounced deceased on the second postoperative day. This is the second case of intracranial hemorrhage following tozinameran administration caused by a ruptured middle cerebral artery bifurcation aneurysm. Upon analyzing the case, there might be a connection between the vaccine\'s potential immune-triggering effect on hemodynamic patterns and the rupture of the previously unknown cerebral aneurysm. However, these severe complications do not justify avoiding vaccines; further studies are needed. This study emphasizes the need for increased vigilance in patients with underlying systemic comorbidities who have recently been vaccinated and to share our insights into the potential relationship between tozinameran and intracranial hemorrhage.

BACKGROUND: Both SARS-CoV-2 mRNA-based vaccines [BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna)] have shown high efficacy, with very modest side effects in limiting transmission of SARS-CoV-2 and in preventing the severe COVID-19 disease, characterized by a worrying high occupation of intensive care units (ICU), high frequency of intubation and ultimately high mortality rate. At the INT, in Naples, only the BNT162b2/Pfizer vaccine has been administered to cancer patients and healthcare professionals aged 16 and over. In the present study, the antibody response levels and their decline were monitored in an interval of 6-9 months after vaccine administration in the two different cohorts of workers of the INT - IRCCS \"Fondazione Pascale\" Cancer Center (Naples, Italy): the group of individuals previously infected with SARS-CoV-2 and vaccinated with a single dose; and that of individuals negative for previous exposure to SARS-CoV-2 vaccinated with two doses 21 days apart.
METHODS: Specific anti-RBD (receptor-binding domain) titers against trimeric spike glycoprotein (S) of SARS-CoV-2 by Roche Elecsys Anti-SARS-CoV-2 S ECLIA immunoassay were determined in serum samples of 27 healthcare workers with a previously documented history of SARS-CoV-2 infection and 123 healthcare workers without, during antibody titers\' monitoring. Moreover, geometric mean titers (GMT) and relative fold changes (FC) were calculated.
RESULTS: Bimodal titer decline was observed in both previously infected and uninfected SARS-CoV-2 subjects. A first rapid decline was followed by a progressive slow decline in the 6/9 month-period before the further vaccine boost. The trend was explained by 2 different mathematical models, exponential and power function, the latter revealing as predictive of antibody titer decline either in infected or in not previously infected ones. The value of the prolonged lower vaccine titer was about 1 log below in the 6/9-month interval after the single dose for previously infected individuals with SARS-CoV-2 and the two doses for those not previously infected. The titer change, after the boost dose administration, on the other hand, was ≥ 1.5 FC higher than the titers at the 6/9-month time-points in both cohorts. A similar quantitative immune titer was observed in both cohorts 8 days after the last boost dose. The subsequent immunoresponse trend remains to be verified.
CONCLUSIONS: The results show that a very rapid first decline, from the highest antibody peak, was followed by a very slow decline which ensured immune protection lasting more than 6 months. The apparent absence of adverse effects of the rapid decline on the vaccine\'s immune protective role has been related to a large majority of low avidity antibodies induced by current vaccines. High avidity antibodies with prolonged anti-transmission efficacy show a longer half-life and are lost over a longer interval period. The cellular immunity, capable of preventing severe clinical diseases, lasts much longer. The unbalanced dual activity (cellular vs humoral) while effective in limiting ICU pressure and overall mortality, does not protect against transmission of SARS-CoV-2, resulting in high circulation of the virus among unvaccinated subjects, including the younger population, and the continuous production of variants characterized by changes in transmissibility and pathogenicity. The high mutation rate, peculiar to the RNA virus, can however lead to a dual opposite results: selection of defective and less efficient viruses up to extinction; risk of more efficiently transmitted variants as the current omicron pandemic.
CONCLUSIONS: In conclusion the current bimodal antibody-titer decline, following BNT162b2 mRNA anti-SARS-CoV-2 vaccination, needs a further extended analysis to verify the protective borderline levels of immunity and the optimal administration schedule of vaccine boosters. Our current results can contribute to such goal, besides a direct comparison of other FDA-approved and candidate vaccines.

After the surging rise in the Coronavirus disease 2019 (COVID-19) pandemic, the Food and Drug Administration (FDA) approved emergency approval of vaccinations to prevent life-threatening complications of COVID-19 infection. These vaccines are BNT162b2, mRNA-1273. Later, the FDA also approved JNJ-78436735. COVID-19 vaccination does not have major side effects, but there are some concerning adverse events reported right after vaccination. Myocarditis is one of them. Based on our analysis of 40 case reports, we are presenting the epidemiology and clinical picture of myocarditis related to the COVID-19 vaccine. Based on our analysis, we found that the majority of cases were seen in males with 90% predominance, and these cases were seen in the age group of 29.13 years old (mean, SD of 14.39 years). In 65% of cases, patients took the BNT162b2 vaccine; 30% of cases were reported with the mRNA-1273 vaccine; and 5% of cases with JNJ-78436735. Of all the cases, 80% of them are reported after the second dose of the vaccine with either Moderna or Pfizer. The characteristics of COVID-19 vaccine-related myocarditis were analyzed in this study. We identified several findings, ranging from age, gender, type of vaccination, presentation of symptoms, and diagnosis modality. This depicts the picture of COVID-19 vaccine-related myocarditis and what physicians should expect when dealing with the disease. Our analysis showed that more cases were reported after receiving the BNT162b2 vaccine compared to mRNA-1273 and JNJ-78436735 vaccines. Further research needs to be conducted to analyze the underlying cause of this association.