Antibody levels after BNT162b2 vaccine booster and SARS-CoV-2 Omicron infection

In the present study, immunogenicity data in 61 vaccinated healthcare workers (HCWs) either infection naïve (naïve HCWs) or with infection of Delta and/or Omicron COVID-19 (experienced HCWs) were evaluated up to 270 days after the second dose of BNT162b2 vaccine and up to 90 days after a booster dose. A decrease in antibody levels at 270 days following administration of the second dose (p = 0.0335) was observed, although values did not fall below the positivity threshold (33.8 BAU/ml). After booster vaccination, antibody levels increased after 30 days (p = 0.0486), with much higher values than after first and second vaccination. Antibody levels then decreased at 60 and 90 days after the booster dose. A comparison between mean antibody levels of naïve and experienced HCWs revealed higher values in experienced HCWs, resulting from both natural and vaccination-induced immunity. A total of 14.7% of HCWs contracted the Omicron virus variant after the vaccine booster, although none showed severe symptoms. These results support that a booster dose results in a marked increase in antibody response that subsequently decreases over time.

Evaluation of neutralizing antibodies after vaccine BNT162b2: Preliminary data

It is well-known that the Coronavirus Disease 2019, which is caused by the beta-coronavirus severe acute respiratory syndrome (SARS-CoV-2), emerged in December 2019 followed by an outbreak first reported in Wuhan, China. Thus far, vaccination appears to be the only way to bring the pandemic to an end. In the present study, immunogenicity data was evaluated using LIAISON® SARS-CoV-2 TrimericS IgG assay (DiaSorin S.p.A) among a sample of 52 vaccinated healthcare workers, five of whom were previously infected with SARS-CoV-2 and 47 who were seronegative, over a time span of ≤90 days following the second dose of the BNT162b2 mRNA vaccine. The test detects antibodies against the Trimeric complex (S1, S2 and receptor binding domain). The overall mean value of the serum levels of IgG antibodies to SARS-CoV-2 30 days following the second dose of the vaccine was 1,901.8 binding arbitrary unit (BAU)/ml, after 60 days the mean value declined to 1,244.9 BAU/ml. The antibody levels then reached a plateau, as confirmed by the antibody test carried out 90 days following the second dose, which revealed a mean value of 1,032.4 BAU/ml (P<0.0001). A higher level was observed at all three times in male subjects compared with female subjects, and in younger male participants compared with female participants, although these differences did not reach a statistically significant level. Similarly, no significant difference was found in antibody values at different times according to age. After the second dose of the vaccine, two subjects were infected with SARS-CoV-2, and an increase in antibody values in the third assay was observed in both individuals.

Syndromic surveillance of vaccine-associated adverse events in U.S. emergency departments

The Centers for Disease Control and Prevention explored use of emergency department (ED) visit data, during 2018-2020, from the National Syndromic Surveillance Program to monitor vaccine-associated adverse events (VAE) among all age groups. A combination of chief complaint terms and administrative diagnosis codes were used to detect VAE-related ED visits. Postvaccination fever was among the top 10 most frequently noted diagnoses. VAE annual trends demonstrated seasonality; visits trended upward starting in September of each year, coinciding with the administration of seasonal influenza vaccines. The 2020 VAE-related visit trend declined below the 2018 and 2019 baselines during March 22-September 5, 2020, before returning to the seasonal pattern. VAE-related visits declined in children aged 3-18 years in 2020 compared with 2018-2019, especially in the back-to-school months. These findings demonstrate that syndromic surveillance can complement traditional VAE reporting systems without an additional demand on data collection resources.