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OBESITY MAY HAMPER SARS-CoV-2 VACCINE IMMUNOGENICITY
Raul Pellini
1
, Aldo Venuti*
2
,
Fulvia Pimpinelli
3
, Elva Abril
3
, Giovanni Blandino
4
, Flaminia Campo
1
, Laura Conti
5
,
Armando De Virgilio
6
, Federico De Marco
7
, Enea Gino Di Domenico
3
, Ornella Di Bella
8
, Simona Di Martino
9
, Fabrizio
Ensoli
3
, Diana Giannarelli
10
, Chiara Mandoj
5
, Valentina Manciocco
1
, Paolo Marchesi
1
, Francesco Mazzola
1
, Silvia
Moretto
1
, Gerardo Petruzzi
1
, Fabrizio Petrone
11
, Barbara Pichi
1
, Martina Pontone
3
, Jacopo Zocchi
1
, Antonello Vidiri
12
,
Branka Vujovic
8
, Giulia Piaggio
13
, Aldo Morrone
14
, Gennaro Ciliberto
15
1
Department Otolaryngology Head and Neck Surgery, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici
Ospitalieri (IFO), Rome, Italy
2
HPV Unit, UOSD Tumor Immunology and Immunotherapy, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici
Ospitalieri (IFO), Rome, Italy
3
Department of Microbiology and Virology, IRCCS San Gallicano Dermatological Institute, Istituti Fisioterapici Ospitalieri (IFO),
Rome, Italy.
4
Oncogenomic and Epigenetic Unit, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome,
Italy
5
Department Clinical Pathology and Cancer Biobank, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici
Ospitalieri (IFO), Rome, Italy
6
Department of Biomedical Sciences, Humanitas University, Pieve Emanuele - Milan, Italy
7
Department of RiDAIT, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy
8
Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy
9
Department of Pathology, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy
10
Biostatistical Unit, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy
11
U.O.C. D.I.T.R.A.R. IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy
12
Department of Radiology and Diagnostic Imaging, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri
(IFO), Rome, Italy
13
UOSD SAFU, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy
14
Scientific Direction, IRCCS San Gallicano Dermatological Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy.
15
Scientific Direction, IRCCS Regina Elena National Cancer Institute, Istituti Fisioterapici Ospitalieri (IFO), Rome, Italy
*Corresponding author:
Aldo Venuti, MD, PhD
IRCCS “Regina Elena” National Cancer Institute
Via Elio Chianesi 53
00144, Rome – Italy
aldo.venuti@ifo.gov.it
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NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.
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ABSTRACT
Background: The first goal of the study was to analyse the antibody titre 7 days after the second dose of
BNT162b2 vaccine in a group of 248 healthcare workers (HCW). The second goal was to analyse how the
antibody titre changes in correlation with age, gender and BMI.
Methods: Participants were assigned to receive the priming dose at baseline and booster dose at day 21.
Blood and nasopharyngeal swabs were collected at baseline and 7 days after second dose of vaccine.
Findings: 248 HWCs were analysed, 158 women (63.7%) and 90 men (36.3%). After the second dose of
BNT162b2 vaccine, 99.5% of participants developed a humoral immune response.
The geometric mean concentration of antibodies among the vaccinated subjects after booster dose (285.9
AU/mL 95% CI: 249.5-327.7); was higher than that of human convalescent sera (39.4 AU/mL, 95% CI:
33.1-46.9), with p<0.0001. The antibody titre was found to be higher in young and female participants. A
strong correlation of BMI classes with antibody titres was noticed: humoral response was more efficient in
the group with under- and normal-weight vs the group with pre- and obesity participants (p<0.0001 at T1).
Interpretation: These findings imply that females, lean and young people have an increased capacity to
mount humoral immune responses compared to males, overweight and the older population. Although
further studies are needed, this data may have important implications for the development of vaccination
strategies for COVID-19, particularly in obese people.
Funding: None
Key words: COVID-19; SARS-CoV-2; vaccine; obesity; antibodies; serum titre
. CC-BY-ND 4.0 International licenseIt is made available under a
perpetuity.
is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint
The copyright holder for thisthis version posted February 26, 2021. ; https://doi.org/10.1101/2021.02.24.21251664doi: medRxiv preprint
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INTRODUCTION
Since the first cases of COVID-19 were described in December, a health emergency with major social and
economic disruptions has spread worldwide.
The World Health Organization, on the 11th of March 2020, announced the severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) outbreak a pandemic.
Although rigorously applied, control measures such as the use of masks, physical distancing and contact
tracing, helped to limit viral transmission; however no substantial benefits were noted, and it soon became
clear that vaccines represented the main viable road to get out of the pandemic.
Since the genetic sequence of SARS-CoV-2 on January 11, 2020, scientists and biopharmaceutical
manufacturers focused their research on developing a vaccine.
Currently, there are over 238 vaccine candidates being developed against COVID-19, with 63 at various
stages of human clinical trial test(1).
A large clinical trial phase 2/3 with 44,000 people showed that a two-dose regimen of the vaccine
BNT162b2, developed by BioNTech and Pfizer, has 95% efficacy in preventing symptomatic COVID-19.
The same study showed that safety over a median of 2 months was similar to that of other viral vaccines(2).
As a consequence of these results, on December 11th, 2020, the U.S. Food and Drug Administration
authorized vaccine BNT162b2 for emergency use. This was soon followed by the European Medicines
Agency on 21 December 2020.
Nonetheless, the efficacy of protection from infection of BNT162b2 vaccine has not been established.
To overcome this limit, antibody titre can be used to predict protection against SARS-CoV-2, as already
done for many viruses in humans and for SARS-CoV-2 in animal challenges(3, 4).
Two studies by BioNTech/ Pfizer’s presented immunogenicity data: preliminary results are encouraging, but
antibody responses with a double 30 micrograms regimen is reported only in 22 patients(5, 6).
Krammer et al, described the antibody responses in 109 individuals with and without documented pre-
existing SARS-CoV-2 immunity (seronegative: 68, seropositive: 41). They advised that a single dose of
mRNA vaccine elicits very rapid immune responses in seropositive individuals with post-vaccine antibody
titres that are comparable to or exceed titres found in naïve individuals who received two vaccinations(7).
More data is certainly needed to assess the efficacy and thus protection against the virus.
In this setting, we report the early experience with BNT162b2 vaccination in a medical population. The first
goal of our study was to analyse the antibody titre response 7 days after the second dose of vaccine in a
group of 248 healthcare workers (HCW). Our second goal was to analyse how the antibody titre changes in
correlation with age, gender and BMI.
MATERIALS AND METHODS
Study design and participants
A collaborative team carried out an immunogenicity evaluation among HCWs vaccinated at the Istituti
Fisioterapici Ospitalieri (IFO).
The study protocol complied with the tenets of the Helsinki declaration and was approved by the institutional
scientific ethics committee (protocol RS1463/21).
All the enrolled participants met the following inclusion criteria: 1) provided written informed consent 2) age
between 18-75 years, 3) health workers employed at the Istituti Fisioterapici Ospitalieri (IFO), 4)
vaccinated at the Istituti Fisioterapici Ospitalieri (IFO).
Key exclusion criteria included: 1) evidence of current or previous SARS-CoV-2 infection by either
anamnesis, serological or microbiological test through nasopharyngeal swab before enrolment, 2) treatment
with immunosuppressive therapy, 3) immunosuppression-associated pathology, and 4) pregnancy.
Human SARS-CoV-2 infection convalescent sera (n=59) were drawn from HCW donors (mean age 45) at
least 14 days after PCR-confirmed diagnosis and at a time when the participants were asymptomatic. The
donors were divided into groups based on symptoms: symptomatic infections (n:41); asymptomatic
infections (n:18).
The manufacturer’s (BioNTech/Pfizer, USA) instructions for storage and administration of vaccine were
followed.
The COVID-19 mRNA Vaccine BNT162b2 was stored in an ultra-low temperature freezer at -80°C. The
undiluted vaccine was stored for up to 2 hours at temperatures up to 25°C, prior to use.
The mRNA vaccine was administered as a 30 microgram / 0.3ml intramuscular injection into the deltoid
muscle on days 1 and 22 of the study.
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perpetuity.
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We used a questionnaire to collect data on the participants’ socio-demographic and health characteristics.
Participants were stratified by age, sex and body mass index (BMI).
Participants had a nasopharyngeal swab for SARS-CoV-2 RT-PCR testing (Viracor, Eurofins Clinical
Diagnostics, U.S.A.), and were assessed for the presence of SARS-CoV-2–binding antibodies (The
LIAISON® SARS-CoV-2 S1/S2 IgG, test Diasorin, Italy) and at baseline and 7 days after BNT162b2
booster dose.
Assessment of SARS-CoV-2 in nasopharyngeal swab
A nasopharyngeal swab was collected by standard procedures and presence of SARS-CoV-2 was determined
by RT-PCR testing (Viracor, Eurofins Clinical Diagnostics, U.S.A.) following the manufacturer’s
instruction.
Assessment of SARS-CoV-2 Binding Antibody
Peripheral venous blood samples of 7-8 mLs were obtained, serum collected and stored at +4 °C.
Quantitative measurement of IgG antibodies against S1/S2 antigens of SARS-CoV-2 was performed with a
commercial chemiluminescent immunoassay (The LIAISON® SARS-CoV-2 S1/S2 IgG, test Diasorin, Italy)
according to the manufacturer’s instruction.
Statistical analysis
Log Geometric Mean of AU/mL was reported. To assess differences between groups, Student's t-test
(Bonferroni’s adjusted) was used when comparing between 2 groups and ANOVA when comparing between
>2 groups.
Repeated measurement ANOVA was used to assess differences between groups over time.
Age was categorized according to quartiles. Statistical analysis was done using SPSS Statistics software
version 21. A p < 0.05 was considered statistically significant.
RESULTS
Two hundred forty-eight HWCs were analysed, 158 women (63.7%) and 90 men (36.3%). Median age was
47 years, (range 23-69). Nasopharyngeal swab test at baseline and 7 days after booster dose did not reveal
presence of SARS-CoV-2 in any of the participants.
Results are summarized in table 1. After second dose of BNT162b2, 99.5% of participants developed a
humoral immune response respect to the baseline (T0) serum level. Only one participant was non-responder
after the second dose.
Seven days after the booster dose, S1-S2 binding antibody concentration was in the range of 3.8-2460
AU/mL. The antibody geometric mean concentration (AbGMC) among vaccinated subjects (285.9 AU/mL
95% CI: 249.5-327.7) was higher than that of human convalescent sera (39.4 AU/mL, 95% CI: 33.1-46.9),
with p<0.0001.
The antibody titre was greater in younger participants compared to older participants with statistically
significant differences: <=37 vs 47-56 p=0.005, <=37 vs >56 p<0.0001, 37-47 vs >56 p=0.01. AbGMC of
single participants among different age classes is reported in figure 1.
Antibody responses of greater magnitude was shown more frequently in women than in men; this difference
(338.5 AU/mL vs 212.6 AU/mL) was statistically significant with p=0.001.
AbGMC of single participants among BMI classes is showed in figure 2. A correlation between BMI classes
and antibody titres was noticed with p=0.02. Interestingly, humoral response was more efficient in under-
and normal-weight group vs pre-obesity and obesity group (p<0.0001). This association was confirmed after
adjusting for age (p=0.003).
Finally, hypertension was associated with lower AbGMC titre with p=0.006. However, after age matching
this data there was no statistical significance found (p=0.22).
DISCUSSION
During the last year we have witnessed a remarkable effort of researchers and the pharmaceutical industry in
the development of a vaccine against SARS-CoV-2.
With this paper, we present an independent study on antibody titre against S1/S2 SARS-CoV-2 in HCWs 7
days after the second dose of BNT162b2: almost 100% of participants demonstrated antigen-specific
humoral response respect to baseline level and no one showed positive nasopharyngeal test during the study.
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is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint
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5
Although the role of neutralizing antibodies to SARS-CoV-2 is under investigation, measurement of serum
neutralizing activity has been demonstrated to correlate with protection for other respiratory viruses, such as
influenza(3) or respiratory syncytial virus(8)
and is commonly accepted to be a functional biomarker of in
vivo disease protection(9). In this study we utilized a chemiluminescent immunoassay that detect S1/S2
specific antibodies but it was not specifically designed to detect neutralizing antibodies. However, the
manufacturer indicates that 80 AU/mL has a correlation of 100% with a 1:160 titre of a Plaque reduction
neutralization test (PRNT90). Thus, we can assume that at least a substantial proportion (93.2%) of enrolled
population showing >80AU/ml should have developed neutralizing antibodies.
Our study clearly shows immune response in all participants and a correlation with age, gender and BMI:
higher antibody titre was detected in younger people, in females and in normal-weight participants (BMI
<25).
Our participants were grouped according to the BMI classification, which is based on the western
classification of obesity(10). BMI is considered a crude measure that does not distinguish between under
skin and visceral fat accumulation. Indeed, people in some areas of Asia, Middle East and Latin America
tend to accumulate visceral fat at lower BMI. However, we believe that this classification could favor data
comparison among different studies, as non-western researchers, like those in China, are also reporting their
results using Western definitions of BMI(11).
The effectiveness of COVID-19 vaccines in people with obesity is a critical issue. Since obesity is a major
risk factor for morbidity and mortality for patients with COVID-19(12), it is mandatory to plan an efficient
vaccination program in this subgroup. Evidence suggests that SARS-CoV-2 infections are more severe and
linger for about five days longer in people who are obese than in those who are lean(13).
The constant state of low-grade inflammation, present in overweight people, can weaken some immune
responses, including those launched by T cells, which can directly kill infected cells(14).
Obesity is linked to less-diverse populations of microbes in the gut, nose and lung, with altered compositions
and metabolic functions compared with those in lean individuals. Recently, researchers reported that changes
of gut microbiome, by taking antibiotics, may alter responses to the flu vaccine(15). Moreover, vaccines
against influenza, hepatitis B and rabies have shown reduced responses in those who are obese compared
with those who are lean(16). To our knowledge, this study is the first to analyse COVID-19 vaccine response
in correlation to BMI. Our data stresses the importance of close vaccination monitoring of obese people,
considering the growing list of countries with obesity problems. According to the latest data from the World
Health Organization, 39% of adults aged 18 years and over were overweight, and 13% were obese. If our
data was to be confirmed by larger studies, giving obese people an extra dose of the vaccine or a higher dose
could be options to be evaluated in this population.
Evidence from a recent meta-analysis suggest that COVID-19 exhibits differences in morbidity and mortality
between sexes. Male patients have almost three times the odds of necessitating intensive treatment unit
admission and higher odds of death compared to females(17). Our results also confirmed this difference in
vaccine response. Women produce higher antibody titres in response to the trivalent inactivated seasonal
influenza vaccination (TIV)(18, 19), as well as to most other pathogen vaccines(20). More specifically,
females achieve equivalent protective antibody titres to males at half the dose of TIV(21), with serum
testosterone levels inversely correlating with TIV antibody titres(22).
These findings imply that female, lean and young people have an increased capacity to mount humoral
immune responses compared to male, overweight and older population. Although further studies are needed,
this data may have important implications to the development of vaccination strategies for COVID-19,
particularly in obese people. At the same time, we strongly believe that our results are extremely
encouraging and useful for the scientific community.
All the authors have made substantial contributions to the work; all the authors approved the final manuscript.
No honorarium grant or other form of payment was given to anyone of the authors to produce the manuscript.
We have no conflict of interest to disclose.
. CC-BY-ND 4.0 International licenseIt is made available under a
perpetuity.
is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint
The copyright holder for thisthis version posted February 26, 2021. ; https://doi.org/10.1101/2021.02.24.21251664doi: medRxiv preprint
