Time course of antibody concentrations against the spike protein of SARS-CoV-2 among healthy hospital workers up to 200 days after their first COVID-19 vaccination

Comparative Analysis of IgG Antibody Titers Induced by Three Different SARS-COV-2 Vaccines in Healthy Adults of Pakistan

Covid-19 is a contagious disease caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). In order to control this disease, different effective vaccines have been developed. This study is an attempt to determine the strength and duration of immunogenicity of various established vaccines. This cross-sectional, observational study was conducted to compare the efficacy of three different vaccines; Pfizer BNT 162b2, Sinovac, and CanSino, respectively, after a duration of 3 months, in the healthy adult population of Pakistan. In this study 371 healthy participants (aged 12-25 years) of both genders (male and females) were enrolled. The blood sample was drawn 90 days after the complete vaccination process. The humoral response (IgG) was analyzed by electrochemiluminescence immunoassay (ECLIA) method with Roche Anti-SARS-CoV-2 S analyzer kit. Descriptive statistical analysis was performed using IBM SPSS statistics version 22 and P < 0.05 was considered significant. The mean antibody titer in Pfizer-group was 12,536.35 U/mL, followed by 5168.68 U/mL in the Sinovac group and 4284.32 U/mL in the CanSino group. The Pfizer-group showed gender-specific significant differences, with higher antibody levels in males (P = 0.006) as compared to Sinovac and Cansino groups. The Mean IgG antibody levels of the Pfizer-vaccinated group were significantly higher than the Sinovac-vaccinated group and the CanSino-vaccinated group (P = 0.000, each). However, the mean difference between the Sinovac-vaccinated group and the CanSino-vaccinated group was not significant. Vaccine-induced seropositivity was found in the whole cohort. The mRNA-based vaccine produced the highest immune response, and thus, it is recommended for future application.

Determinants of the willingness to get the third COVID-19 vaccine dose among health care workers

OBJECTIVE

To characterize the willingness to get the third COVID-19 vaccine dose among health care workers (HCWs).

METHODS

A cross-sectional study using a self-administered questionnaire proposed on a voluntary basis to all HCWs of a French teaching hospital in October and November 2021.

RESULTS

Of 1,655 HCWs who completed the questionnaire, 64.2% were willing to receive the third dose, 20.1% were hesitant, and 15.7% were reluctant. On multivariate analysis, older age (P<0.0001), medical and executive staff, willingness to receive the flu vaccine (OR=5.72 [4.24-7.64]), previous vaccine scheme with ChAdOx1 nCoV-19 (AstraZeneca) (OR=2.13 [1.58-2.87]), and history of COVID-19 with a complete COVID-19 vaccine scheme (OR=2.77 [1.04-7.41]) were independent predictors of HCWs' willingness to get the third dose.

CONCLUSIONS

One third of HCWs were hesitant or opposed to a third COVID-19 vaccine dose. Better knowledge of determinants of the willingness to get this third dose may improve communication and vaccine strategy.

COVID-19 Vaccination in Health Care Workers in Italy: A Literature Review and a Report from a Comprehensive Cancer Center

The coronavirus disease 2019 pandemic still represents a global public health emergency, despite the availability of different types of vaccines that reduced the number of severe cases, the hospitalization rate and mortality. The Italian Vaccine Distribution Plan identified healthcare workers (HCWs) as the top-priority category to receive access to a vaccine and different studies on HCWs have been implemented to clarify the duration and kinetics of antibody response. The aim of this paper is to perform a literature review across a total of 44 studies of the serologic response to COVID-19 vaccines in HCWs in Italy and to report the results obtained in a prospective longitudinal study implemented at the Fondazione IRCCS Istituto Nazionale Tumori (INT) of Milan on 1565 HCWs. At INT we found that 99.81% of the HCWs developed an antibody response one month after the second dose. About six months after the first serology evaluation, 100% of the HCWs were still positive to the antibody, although we observed a significant decrease in its levels. Overall, our literature review results highlight a robust antibody response in most of the HCWs after the second vaccination dose. These figures are also confirmed in our institutional setting seven months after the completion of the cycle of second doses of vaccination.

Dynamic observation of SARS-CoV-2 IgM, IgG, and neutralizing antibodies in the development of population immunity through COVID-19 vaccination

Background

Currently, mass vaccine inoculation against coronavirus disease‐2019 (COVID‐19) has been being implemented globally. Rapid and the large‐scale detection of serum neutralizing antibodies (NAbs) laid a foundation for assessing the immune response against SARS‐CoV‐2 infection and vaccine. Additional assessments include the duration of antibodies and the optimal time for a heightened immune response.

Methods

The performance of five surrogate NAbs—three chemiluminescent immunoassay (CLIA) and two enzyme‐linked immunosorbent assays (ELISAs)—and specific IgM and IgG assays were compared using COVID‐19‐vaccinated serum (n = 164). Conventional virus neutralization test (cVNT) was used as a criterion and the diagnostic agreement and correlation of the five assays were evaluated. We studied the antibody responses after the two‐dose vaccine in volunteers up to 6 months.

Results

The sensitivity and specificity of five surrogate NAb assays ranged from 84% to 100%. Our cVNT results indicated great consistency with the surrogate assays. At 28 days after primary vaccination, the seropositivities of the NAbs, IgG, and IgM were 6%, 4%, and 13%, respectively. After the booster dose, seropositivities reached 14%, 65%, and 97%, respectively. Six months after receipt of the second dose, the NAb positive rate was eventually maintained at 66%. In all COVID‐19 convalescents, patients were detected with 100% NAb sat three months after discharge.

Conclusion

COVID‐19 vaccine induced a humoral immune response lasting at least six months. Rapid serological detection was used as a proxy for identifying changes in immunity levels and as a guide to whether an individual may require a booster vaccination.