Serological Response to SARS-CoV-2 Messenger RNA Vaccine: Real-World Evidence from Italian Adult Population

Abstract

Background: This study aims to investigate the extent of the BNT162b2 mRNA vaccine-induced antibodies against SARS-CoV-2 in a large cohort of Italian subjects belonging to the early vaccinated cohort in Italy. Methods: A prospective study was conducted between December 2020 and May 2021. Three blood samples were collected for each participant: one at the time of the first vaccine dose (T0), one at the time of the second vaccine dose, (T1) and the third 30 days after this last dose (T2). Results: We enrolled 2591 fully vaccinated subjects; 16.5% were frail subjects, and 9.8% were over 80 years old. Overall, 98.1% of subjects were seropositive when tested at T2, and 76.3% developed an anti-S IgG titer ≥4160 AU/mL, which is adequate to develop viral neutralizing antibodies. Seronegative subjects at T1 were more likely to remain seronegative at T2 or to develop a low–intermediate anti-S IgG titer (51–4159 AU/mL). Conclusions: In summary, vaccination leads to detectable anti-S IgG titer in nearly all vaccine recipients. Stratification of the seroconversion level could be useful to promptly identify high-risk groups who may not develop a viral neutralizing response, even in the presence of seroconversion, and therefore may remain at higher risk of infection, despite vaccination.

Determinants of antibody responses to two doses of ChAdOx1 nCoV-19 or BNT162b2 and a subsequent booster dose of BNT162b2 or mRNA-1273: population-based cohort study (COVIDENCE UK)

“…Where population-based studies have been done, 4,7,8 these did not compare the effect of two doses of viral vector vs mRNA vaccines on host response; neither did they systematically ascertain participants' pre-vaccination SARS-CoV-2 serostatus, which is an important potential confounder of associations reported. Moreover, these studies did not investigate effects of modifiable factors that have been posited to influence responses to vaccination, such as time of day of inoculation, 14 nutrition, 15 sleep, 16 alcohol use, 17 tobacco smoking 18 and peri-vaccination use of anti-pyretic analgesics.…”

“…3 Existing studies investigating determinants of vaccine immunogenicity have reported that lower antibody responses following SARS-CoV-2 vaccination associate with administration of viral vector vs messenger RNA (mRNA) vaccines, older age, poorer general health, immunosuppression and shorter inter-dose intervals. [4][5][6][7][8][9][10][11] Higher postvaccination antibody titres are seen in those with evidence of SARS-CoV-2 infection before vaccination. 9,12,13 However, these studies are limited in several respects: many are conducted in specific populations such as health care workers 5,9,12,13 or in individuals with a particular demographic or clinical characteristic that may influence vaccine immunogenicity, 6,10,11 which may constrain generalisability of their results.…”

“…9,12,13 However, these studies are limited in several respects: many are conducted in specific populations such as health care workers 5,9,12,13 or in individuals with a particular demographic or clinical characteristic that may influence vaccine immunogenicity, 6,10,11 which may constrain generalisability of their results. Where population-based studies have been done, 4,7,8 these did not compare the effect of two doses of viral vector vs mRNA vaccines on host response; neither did they systematically ascertain participants’ pre-vaccination SARS-CoV-2 serostatus, which is an important potential confounder of associations reported. Moreover, these studies did not investigate effects of modifiable factors that have been posited to influence responses to vaccination, such as time of day of inoculation, 14 nutrition, 15 sleep, 16 alcohol use, 17 tobacco smoking 18 and peri-vaccination use of anti-pyretic analgesics.…”

Can Individuals with Suboptimal Antibody Responses to Conventional Antiviral Vaccines Acquire Adequate Antibodies from SARS-CoV-2 mRNA Vaccination?

“…The BNT162b2 vaccine has been highly effective in preventing clinically significant COVID-19 [ 8 , 9 , 10 , 11 ]. However, there is limited information available about the effectiveness of the BNT162b2 vaccine in individuals with a suboptimal response to conventional vaccines.…”

“…The BNT162b2 mRNA vaccine (Pfizer–BioNTech) is highly effective at preventing clinically significant COVID-19 [ 8 , 9 , 10 , 11 ], reducing the incidence of asymptomatic infection and associated infectivity [ 12 , 13 ], and preventing the spread of COVID-19 [ 9 ]. The BNT162b2 vaccine was the first SARS-CoV-2 vaccine to be approved in Japan, and priority vaccination of healthcare workers (HCWs) began in February 2021 in order to safeguard the medical delivery system [ 14 ].…”