Effectiveness of the mRNA BNT162b2 vaccine six months after vaccination: findings from a large Israeli HMO

Abstract

Israel is currently experiencing a new wave of CoVid-19 infection, six months after implementing a national vaccination campaign. We carried out three discrete analyses using data from a large Israeli HMO to determine whether IgG levels of those fully vaccinated drop over time, the relationship between IgG titer and subsequent PCR-confirmed infection, and compare PCR-confirmed infection rates by period of vaccination. We found that mean IgG antibody levels steadily decreased over the six-month period in the total tested population, and in all age groups. An inverse relationship was found between IgG titer and subsequent CoVid-19 infection (PCR-positive). Those participants vaccinated in the first two months of the campaign were more likely to become infected than those subsequently vaccinated. The 60+ vaccinated had lower initial IgG levels, and were at greater risk of infection. The findings support the decision to add a booster vaccine for those aged 60 and over.

Characterization of the significant decline in humoral immune response six months post-SARS-CoV-2 mRNA vaccination: A systematic review

“…This particular study was also limited by the lack of control groups, preventing us from directly comparing the percent decline of those with comorbidities versus healthy populations, although the absolute values of Ab levels were significantly lower in those with comorbidities compared to the total sample population. 25 Regardless of this limitation, when taken together with other studies in this systematic review, those with comorbidities exhibited a similar trend in percent decline with the general population and other cohorts.…”

“…There is 95% decrease days after the peak rise of total antibody titer on day 0-29 after full vaccination Kertes et al 25 Pfizer-BioNTech Israel 8395…”

“…Ab titers of females were higher even after humoral decline in all studies (Table 3); however, the percentage decline from the peak was similar for both sexes (Figure 4). 12,25 While it is important to note that overall Ab titers may be influenced by the larger female population cohort (6,238 females vs. 3,128 males) involved in the included studies, this might be attributed to the sex-based difference in humoral immunity which affects vaccine responses. Previous studies indicated that females have a greater humoral response attributed to hormonal differences and X chromosomes leading to biallelic expression of certain genes.…”

Third dose of anti-SARS-CoV-2 vaccine for patients with cancer: Should humoral responses be monitored? A position article

“…Based on a correlation rate with Nabs of approximatively 0.8, individuals with anti-S titers below 141 BAU/mL ( Wantai Biological Pharmacy Enterprise Co., Ltd, China ) displayed about 10% risk of becoming infected within a year versus a 1.3% risk for HCW with titers between 141 and 1700 BAU/mL, and no infection risk for those exhibiting titers above 1700 BAU/mL. In the Maccabi Health Care Services Israeli study ( 65 ), 5,141 vaccinated subjects underwent anti-S IgG dosages ( Abbott IgG II ) at both four weeks and 6 months after D2 vaccination. The rate of participants with a PCR-positive SARS-Cov-2 infection significantly differed depending on anti-S IgG titer levels, ranging from 1.2 to 1.3% for those with anti-S titers below 299 AU/ml (<42 BAU/mL), yet being only 0.2% for those with anti-S titers above 300 AU/ml (>42 BAU/mL), (p=.004).…”

“…In the Maccabi Health Care Services Israeli study ( 65 ), 5,141 vaccinated subjects underwent anti-S IgG dosages ( Abbott IgG II ) at both four weeks and 6 months after D2 vaccination. The rate of participants with a PCR-positive SARS-Cov-2 infection significantly differed depending on anti-S IgG titer levels, ranging from 1.2 to 1.3% for those with anti-S titers below 299 AU/ml (<42 BAU/mL), yet being only 0.2% for those with anti-S titers above 300 AU/ml (>42 BAU/mL), (p=.004).…”