The binding responses and temporal dynamics of antibodies elicited against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) due to vaccination must be fully understood for the design of future vaccination strategies.
A new study was published in PLUS ONE Characterizes the antibody response to BNT162b2, the coronavirus 2019 (COVID-19) vaccine from Pfizer-BioNTech. This study analyzes the temporal dynamics of the response of immunoglobulin G (IgG) and IgM antibodies to five different SARS-CoV-2 epitopes over a six-month period after vaccination.
Stady: 6-month serological response to the Pfizer-BioNTech COVID-19 vaccine among healthcare workers. Image Credit: Flowersandtraveling / Shutterstock.com
BNT162b2 . Vaccine
BNT162b2 is a messenger ribonucleic acid (mRNA) vaccine by Pfizer-BioNTech. The US Food and Drug Administration (FDA) authorized the BNT162b2 vaccine for emergency use on December 11, 2020.
SARS-COV-2 binds to and infects host cells through the spike (S) protein receptor-binding domain exposed on the surface of the virus. The BNT162b2 mRNA vaccine encodes the SARS-CoV-2 RBD. RNA is modified to nucleosides and surrounded by lipid nanoparticles.
Six-month serological response assessment
Healthcare workers were among the first individuals to receive the COVID-19 vaccine. Therefore, the current observational study enrolled adult participants working in a large healthcare system.
Study participants received the BNT162b2 vaccine at week 0 and week 3. Blood samples were collected on the day of vaccination (baseline), as well as two weeks, four weeks, three months and six months after vaccination.
Antibodies to SARS-CoV-2 were analyzed using a Maverick SARS-CoV-2 multi-antigen panel that detected nucleocapsid, spike S1 RBD, spike S1S2, spike S1 and spike S2.
Change in total antibody, IgM, and IgG responses across all time points was assessed.
A total of 15 study participants completed all five blood groups. Of the 15 participants, six were office workers, three were nurses, one was a physician assistant, two were paramedics, two were physicians, and one had an unknown role in the health care system.
The average age of the participants was 44 years and 82% of the participants were female. None of the participants reported previous symptoms of COVID-19 or previous PCR testing for COVID-19.
Sera samples were analyzed to examine the humoral response to BNT162b2 vaccine. Ten different types of SARS-CoV-2 antibodies were evaluated, including four IgM and four IgG antibodies targeting each of four different spike protein epitopes, as well as one IgM antibody and one IgG antibody targeting the nucleocapsid epitope.
All participants had a significant serological response over time to the total antibody. Serological response over time was significant for both IgG and IgM antibody responses. Serological response was largely driven by IgG antibodies.
Vaccination elicited a dominant IgG antibody response. Most of the participants had an IgG response two weeks after vaccination.
There were significant increases in the mean response between baseline and the fourth week of anti-SARS-CoV-2 IgG versus spike S1, spike S1 RBD, spike S1S2 and spike S2 IgG. Thus, the IgG response was observed in the two weeks following inoculation in most participants and continued to increase in the fourth week. However, the IgG response against all spiny protein epitopes significantly decreased from three months up to six months.
The IgM response of all epitopes was minimal; However, one patient had pre-existing IgG antibodies against the nucleocapsid antigen. This confirms a previous asymptomatic infection.
Temporal IgG response to SARS-CoV-2. Immunoglobulin G antibody response to SARS-CoV-2-related epitopes at baseline, week 2, 4, month 3 and month 6 in subjects given Pfizer-BioNTech COVID-19 vaccine at week 0 and week 3. A response has been reported Antibody in Genalyte Response Units (GRU). NS represents a p-value > 0.05, * represents a p-value 0.05, ** represents a p-value ≤ 0.01, *** represents a p-value ≤ 0.001, **** represents a p-value ≤ 0.0001.
The spike protein antibody response is significantly reduced six months after vaccination with BNT162b2 vaccine. However, it remains to be determined whether a decrease in this antibody is associated with diminished immunity.
For this purpose, the change in infection risk should be assessed with respect to the post-vaccination time. The cellular response to vaccination should also be examined to determine complete vaccine-directed immunity.
The current study provides data to inform current research investigating the potential of a booster dose to extend the level and duration of immunity. This is particularly important in the context of emerging SARS-CoV-2 variants.
This study also provides new insights into the response that can be expected for other mRNA vaccination targets. Furthermore, the study results provide a comparison for assessing the humoral response in immunocompromised patients, as this population group requires innovative strategies to enhance vaccine immunity.
Immunization with BNT162b2 results in minimal anti-SARS-CoV-2 IgM response against spike protein. This is contrary to natural SARS-CoV-2 infection.
The polyclonal IgG antibody response against the spike protein occurs two weeks after vaccination and continues to increase by the fourth week, but then decreases within three months and continues to decrease up to six months.
- Sham, J, Pandey, S, New, J, and others. (2022) 6-month serological response to the Pfizer-BioNTech COVID-19 vaccine among healthcare workers. PLUS ONE 17(4). doi: 10.1371/journal.pone.0266781.