Covid 19

COVID-19 VACCINES
Presented by
Lecturer Hamed Ibrahim Mohammad
B.D.S, MSc Oral and Maxillofacial surgery
Lecturer Hamsa Zaki
B.D.S, MSc Conservative Dentistry

 A COVID 19 vaccine is a vaccine intended to provide acquired immunity against severe acute
respiratory syndrome coronavirus 2 (SARS CoV 2), the virus causing coronavirus disease
2019 (COVID 19).
 On 10 January 2020, the SARS-CoV-2 genetic sequence data was shared through
GISAID(global initiative on sharing avian influenza virus) , and by 19 March, the global
pharmaceutical industry announced a major commitment to address COVID-19.

 In Phase III trials, several COVID 19 vaccines have demonstrated efficacy as high as 95% in
preventing symptomatic COVID 19 infections. As of April 2021, 16 vaccines are authorized by at
least one national regulatory authority for public use: two RNA vaccines (Pfizer–BioNTech and
Moderna), seven conventional inactivate vaccines (BBIBP-CorV, CoronaVac, Covaxin, WIBP-CorV,
CoviVac, Minhai-Kangtai and QazVac), five viral vector vaccines (Sputnik Light, Sputnik V, Oxford–
AstraZeneca, Convidecia, and Johnson & Johnson), and two protein subunit vaccines
(EpiVacCorona and RBD-Dimer). In total, as of March 2021, 308 vaccine candidates are in various
stages of development, with 73 in clinical research, including 24 in Phase I trials, 33 in Phase I–II
trials, and 16 in Phase III development.

Types of vaccines
 Inactivated vaccine
 An inactivated vaccine (or killed vaccine) is a vaccine consisting of virus
particles, bacteria, or other pathogens that have been grown in culture and
then killed to destroy disease producing capacity. In contrast, live vaccines
use pathogens that are still alive (but are almost always attenuated, that is,
weakened). Pathogens for inactivated vaccines are grown under controlled
conditions and are killed as a means to reduce infectivity and thus prevent
infection from the vaccine. The virus is killed using a method such as heat
or formaldehyde.

TYPES OF INACTIVATED VACCINE
 Inactivated vaccines are further classified depending on the method used to inactivate the virus.
 1-Whole virus vaccines use the entire virus particle, fully destroyed using heat, chemicals, or
radiation.
 2- Split virus vaccines are produced by using a detergent to disrupt the virus.
 3- Subunit vaccines are produced by purifying out the antigens that best stimulate the immune
system to mount a response to the virus, while removing other components necessary for the virus
to replicate or survive or that can cause adverse reactions.

 Types include:
 Viral:
 oInjected polio vaccine
 oHepatitis A vaccine
 oRabies vaccine
 oMost influenza vaccines
 oCovid-19 vaccine (Covaxin; CoronaVac Covid-19 Vaccine)
 Bacterial:
 oInjected typhoid vaccine
 oCholera vaccine


Types of vaccines
Attenuated vaccine
 An attenuated vaccine (or a live attenuated vaccine) is a vaccine created by reducing the virulence of
a pathogen, but still keeping it viable (or "live"). Attenuation takes an infectious agent and alters it so
that it becomes harmless or less virulent. Attenuated vaccines stimulate a strong and effective
immune response that is long-lasting. In comparison to inactivated vaccines, attenuated vaccines
produce a stronger and more durable immune response with a quick immunity onset. Attenuated
vaccines function by encouraging the body to create antibodies and memory immune cells in
response to the specific pathogen which the vaccine protects against. Common examples of live
attenuated vaccines are measles, mumps, rubella, yellow fever, and some influenza vaccines.

Attenuated vaccine
 Attenuated vaccines can be administered in a variety
of ways:
 Injections:
 o Subcutaneous (e.g. measles, mumps and rubella vaccine, varicella
vaccine, yellow fever vaccine)
 o Intradermal (e.g. tuberculosis vaccine, smallpox vaccine)
 Mucosal:
 o Nasal (e.g. live attenuated influenza vaccine)
 o Oral (e.g. oral polio vaccine, recombinant live attenuated cholera
vaccine, oral typhoid vaccine)

Attenuated vaccine
 Mechanism
 Vaccines function by encouraging the creation of cells, such as CD8+ and CD4+ T lymphocytes, or
molecules, such as antibodies, that are specific to the pathogen. The cells and molecules can either
prevent or reduce infection by killing infected cells or by producing interleukins. Live attenuated
vaccines tend to help with the production of CD8+ cytotoxic T lymphocytes and T-dependent
antibody responses. Live attenuated vaccines can induce long-term, possibly lifelong, immunity
without requiring multiple vaccine doses. Live attenuated vaccines can also induce cellular immune
responses, which do not rely solely on antibodies but also involve immune cells such as cytotoxic T
cells or macrophages.

Attenuated vaccine
 Safety
 Given pathogens are attenuated, it is extremely rare for pathogens to revert to their pathogenic form and
subsequently cause disease. Additionally, within the five WHO-recommended live attenuated vaccines
(tuberculosis, oral polio, measles, rotavirus, and yellow fever) severe adverse reactions are extremely rare.
However, similar to any medication or procedure, no vaccine can be 100% safe or effective.
 Individuals with compromised immune systems (e.g., HIV-infection, chemotherapy, combined
immunodeficiencies) typically should not receive live-attenuated vaccines as they may not be able to
produce an adequate and safe immune response.
 As precaution, live-attenuated vaccines are not typically administered during pregnancy. This is due to the
risk of transmission of virus between mother and fetus. In particular, the varicella and yellow fever vaccines
have been shown to have adverse effects on fetuses and nursing babies.
 Compared to inactivated vaccines, live-attenuated vaccines are more prone to immunization errors as they
must be kept under strict conditions during the cold chain and carefully prepared.

Attenuated vaccine
 List of attenuated vaccines
 Bacterial vaccines:
 •Anthrax vaccine
 •Cholera vaccine
 •Salmonella vaccine
 •Tuberculosis vaccine
 •Typhoid vaccine

Attenuated vaccine
Viral vaccines
 •Live attenuated influenza vaccine
 •Measles vaccine
 •Mumps vaccine
 •Measles and rubella (MR) vaccine
 •Measles, mumps, and rubella (MMR) vaccine
 •Measles, mumps, rubella and varicella (MMRV) vaccine
 •Polio vaccine
 •Rotavirus vaccine
 •Rubella vaccine
 •Smallpox vaccine
 •Varicella vaccine
 •Yellow fever vaccine

Types of vaccines
 RNA vaccine
 A ribonucleic acid (RNA) vaccine or messenger RNA (mRNA) vaccine is a
type of vaccine that uses a copy of a natural chemical called messenger
RNA (mRNA) to produce an immune response.
 The advantages of RNA vaccines over traditional protein vaccines are
superior design and production speed, lower cost of production, and the
induction of both cellular as well as humoral immunity. A disadvantage in
the Pfizer-BioNTech mRNA vaccine for COVID-19 is that it requires
ultracold storage before distribution.

RNA vaccine
 Mechanism
 The goal of a vaccine is to stimulate the adaptive immune system to create antibodies that
precisely target that particular pathogen, mRNA vaccines operate in a very different manner from
a traditional vaccine. Traditional vaccines stimulate an antibody response by injecting antigens,
an attenuated virus (weakened or harmless virus), or a recombinant antigen-encoding viral
vector (carrier virus engineered to have antigens into muscles. These antigen-containing
ingredients are prepared and grown outside the body.

RNA vaccine
 Mechanism
 In contrast, mRNA vaccines introduce a short-lived synthetically created fragment
of the RNA sequence of a virus into the vaccinated individual. These mRNA
fragments are taken up by dendritic cells – a type of immune system cell – by
phagocytosis. The dendritic cells use their own internal machinery (ribosomes) to
read the mRNA and produce the viral antigens that the mRNA encodes before
destroying the mRNA.
 Once the viral antigens are produced by the host cell, the normal adaptive
immune system processes are followed. Antigens are broken down by
proteasomes, then class I and class II MHC molecules attach to the antigen and
transport it to the cellular membrane, "activating" the dendritic cell.

RNA vaccine
 Mechanism
 Once the dendritic cells are activated, they migrate to lymph nodes, where
the antigen is presented to T cells and B cells. This eventually leads to the
production of antibodies that are specifically targeted to the antigen,
resulting in immunity.
 The benefit of using mRNA to have host cells produce the antigen is that
mRNA is far easier for vaccine creators to produce than antigen proteins or
attenuated virus. Another benefit is speed of design and production.
Moderna designed their mRNA-1273 vaccine for COVID-19 in 2 days.
Another advantage of RNA vaccines is that since the antigens are
produced inside the cell, they stimulate cellular immunity, as well as
humoral immunity.

RNA vaccine
 Mechanism
 mRNA vaccines do not affect or reprogram DNA inside the cell. The
synthetic mRNA fragment is a copy of the specific part of the viral
RNA that carries the instructions to build the antigen of the virus (a
protein spike, in the case of the main coronavirus mRNA vaccines),
and is not related to human DNA. This misconception was circulated
as the COVID-19 mRNA vaccines came to public prominence, and is
a debunked conspiracy theory.

RNA vaccine
 Before 2020, no mRNA technology platform (drug or vaccine) had been authorized for use in
humans, so there was a risk of unknown effects. The 2020 coronavirus pandemic required faster
production capability of mRNA vaccines, made them attractive to national health organisations, and
led to debate about the type of initial authorization mRNA vaccines should get (including emergency
use authorization or expanded access authorization) after the eight-week period of post-final human
trials.

RNA vaccine
 In RNA therapeutics, mRNA vaccines have attracted considerable interest as COVID-19 vaccines.
By December 2020, there were two novel mRNA vaccines for COVID-19 that had completed the
required eight-week period post-final human trials and were awaiting emergency use authorization
(EUA): the Moderna COVID-19 vaccine (mRNA-1273) and the Pfizer–BioNTech COVID-19 vaccine
(BNT162b2). On 2 December 2020, the UK's Medicines and Healthcare products Regulatory
Agency (MHRA) became the first medicines regulator to approve an mRNA vaccine, authorizing the
Pfizer–BioNTech COVID-19 vaccine (Comirnaty) for widespread use. On 11 December 2020, the US
Food and Drug Administration (FDA) issued an EUA for the Pfizer-BioNTech COVID-19 vaccine and
the US Centers for Disease Control and Prevention (CDC) recommended its use in those aged 16
and older on 12 December 2020. On 19 December 2020, the CDC recommended the use of the
Moderna COVID-19 vaccine in adults after the FDA granted an EUA.

RNA vaccine
 Storage
 Because mRNA is fragile, the vaccine must be kept at very low temperatures to avoid
degrading and thus giving little effective immunity to the recipient. Pfizer–BioNTech's
BNT162b2 mRNA vaccine has to be kept between −80 and −60 °C (−112 and −76
°F). Moderna says their mRNA-1273 vaccine can be stored between −25 and −15 °C
(−13 and 5 °F), which is comparable to a home freezer, and that it remains stable
between 2 and 8 °C (36 and 46 °F) for up to 30 days.

Types of vaccines
 Viral vector
 In addition to non-viral delivery methods, RNA
viruses have been engineered to achieve similar
immunological responses. Typical RNA viruses used
as vectors include retroviruses, lentiviruses,
alphaviruses and rhabdoviruses, each of which can
differ in structure and function.

SARS-CoV-2 (COVID -19) VACCINES
 Vaccine platforms being employed for SARS-CoV-2
 1- Whole virus vaccines include both attenuated and inactivated forms of the virus.
 2- Protein and peptide subunit vaccines are usually combined with an adjuvant in
order to enhance immunogenicity. The main emphasis in SARS-CoV-2 vaccine
development has been on using the whole spike protein in its trimeric form, or
components of it, such as the RBD(receptor binding domain) region.
 3- Multiple non-replicating viral vector vaccines have been developed, particularly
focused on adenovirus, while there has been less emphasis on the replicating viral
vector constructs.

 As of January 2021, different technology platforms – with the technology of
numerous candidates remaining undefined are under research and development to
create an effective vaccine against COVID 19. Most of the platforms of vaccine
candidates in clinical trials are focused on the coronavirus spike protein and its
variants as the primary antigen of COVID 19 infection. Platforms being developed in
2020 involved nucleic acid technologies (nucleoside-modified messenger RNA and
DNA), non-replicating viral vectors, peptides, recombinant proteins, live attenuated
viruses, and inactivated viruses.

 RNA vaccine
 An RNA vaccine contains RNA which, when introduced into a tissue, acts as messenger RNA
(mRNA) to cause the cells to build the foreign protein and stimulate an adaptive immune response
which teaches the body how to identify and destroy the corresponding pathogen or cancer cells.
 RNA vaccines were the first COVID-19 vaccines to be authorized in the United Kingdom, the United
States and the European Union. As of January 2021, authorized vaccines of this type are the
Pfizer–BioNTech COVID-19 vaccine and the Moderna COVID-19 vaccine.

 Adenovirus vector vaccines
 These vaccines are examples of non-replicating viral vector vaccines, using an adenovirus shell
containing DNA that encodes a SARS CoV 2 protein. The viral vector-based vaccines against
COVID-19 are non-replicating, meaning that they do not make new virus particles, but rather
produce only the antigen which elicits a systemic immune response.
 As of January 2021, authorized vaccines of this type are the Oxford–AstraZeneca COVID-19
vaccine, the Sputnik V COVID-19 vaccine, Convidecia, and the Johnson & Johnson COVID-19
vaccine.

 Inactivated virus vaccines
 Inactivated vaccines consist of virus particles that have been grown in culture and
then are killed using a method such as heat or formaldehyde to lose disease
producing capacity, while still stimulating an immune response.
 As of January 2021, authorized vaccines of this type are the Chinese CoronaVac,
BBIBP-CorV, and WIBP-CorV; the Indian Covaxin; and the Russian CoviVac.

 Subunit vaccines
 Subunit vaccines present one or more antigens without introducing whole pathogen particles. The
antigens involved are often protein subunits, but can be any molecule that is a fragment of the
pathogen.
 As of April 2021, the two authorized vaccines of this type are the peptide vaccine EpiVacCorona and
RBD-Dimer

 Oxford–AstraZeneca COVID-19 vaccine
 The Oxford–AstraZeneca COVID-19 vaccine, codenamed AZD1222, and sold under the brand names
Covishield and Vaxzevria, is a viral vector vaccine for prevention of COVID-19. Developed by Oxford
University and AstraZeneca, it is given by intramuscular injection, using as a vector the modified
chimpanzee adenovirus ChAdOx1. The efficacy of the vaccine is 76.0% at preventing symptomatic
COVID-19 beginning at 22 days following the first dose and 81.3% after the second dose.

 On 30 December 2020, the vaccine was first approved for use in the UK
vaccination programme, and the first vaccination outside of a trial was
administered on 4 January 2021. The vaccine has since been approved
by several medicine agencies worldwide, such as the European
Medicines Agency (EMA), and the Australian Therapeutic Goods
Administration, and was approved for an Emergency Use Listing by the
World Health Organization .

 The vaccine has a good safety profile, with side effects including
injection-site pain and redness, vomiting, diarrhoea. Enlarged lymph
nodes, decreased appetite, dizziness, sleepiness, sweating, abdominal
pain, itching and rash occurred in less than 1 in 100 people, headache,
and nausea, all generally resolving within a few days. More rarely,
anaphylaxis may occur (the UK Medicines and Healthcare products
Regulatory Agency (MHRA) has 268 reports out of some 21.2 million
vaccinations as of 14 April 2021). The European Medicines Agency
(EMA) has assessed 41 cases of anaphylaxis from around 5 million
vaccinations in the United Kingdom.

 In very rare cases (around 1 in 100,000 people) the vaccine has been associated
with an increased risk of blood clots in combination with low levels of blood platelets.
According to the European Medicines Agency as of 4 April 2021, 222 cases of blood
clots have been reported from the European Economic Area and the UK, where
around 34 million people have received the vaccine.
 The UK MHRA as of 14 April 2021 report an overall case incidence of
thromboembolic events with concurrent low platelets of 7.9 per million doses (less
than 1 in 100,000 people).

 Pfizer–BioNTech COVID-19 vaccine
 The Pfizer–BioNTech COVID-19 vaccine , sold under the brand name Comirnaty, is an mRNA-based
COVID-19 vaccine. It is authorized by the FDA and certain other jurisdictions for use in people aged
12 years and older, and the EMA for people 16 years and older, to provide protection against infection
by the SARS-CoV-2 virus, which causes COVID-19. BioNTech, a German company, developed the
vaccine and collaborated with Pfizer, an American company, for support with clinical trials, logistics,
and manufacturing.
 The vaccine is given by intramuscular injection. It is composed of nucleoside-modified mRNA
(modRNA) encoding a mutated form of the full-length spike protein of SARS-CoV-2, which is
encapsulated in lipid nanoparticles. Vaccination requires two doses given three weeks apart.

 Clinical trials began in April 2020; by November 2020, the vaccine entered phase III clinical trials, with
over 40,000 people participating. An interim analysis of study data showed a potential efficacy of
91.3% in preventing infection within seven days of a second dose.
 The vaccine was the first COVID-19 vaccine to be authorized by a stringent regulatory authority for
emergency use and the first cleared for regular use. In December 2020, the United Kingdom was the
first country to authorize its use on an emergency basis. It is authorized for use at some level in 84
countries including the United States, countries in the European Union, the United Kingdom, Ukraine,
Israel, Brazil, Mexico, Japan and Singapore.
 Monitoring of the primary outcomes from the trials will continue until August 2021, while monitoring of
the secondary outcomes will continue until January 2023.
 As of March 30, 2021, Pfizer and BioNTech aimed to manufacture about 2.5 billion doses in 2021.

 The side effect profile of the Pfizer–BioNTech COVID-19 vaccine is similar to that of other adult
vaccines. During clinical trials, the side effects deemed very common are (in order of frequency): pain
and swelling at the injection site, tiredness, headache, muscle aches, chills, joint pain, and fever.
Fever is more common after the second dose.
 Severe allergic reaction has been observed in approximately eleven cases per million doses of
vaccine administered. According to a report by the US Centers for Disease Control and Prevention,
71% of those allergic reactions happened within 15 minutes of vaccination and mostly (81%) among
people with a documented history of allergies or allergic reactions.
 The European Medicines Agency (EMA) added skin rash and pruritus (itching of the skin) as
uncommon side effects (occurring in fewer than 1 in 100 persons), and urticaria (raised, red and itchy
skin rash) and angioedema (rapid swelling under the skin) as rare side effects (occurring in fewer
than 1 in 1,000 persons) in April 2021.

 Sinopharm COVID-19 vaccine
 Sinopharm BBIBP-CorV, also known as the Sinopharm COVID-19 vaccine, is one of two inactivated
virus COVID-19 vaccines developed by Sinopharm's Beijing Institute of Biological Products. It
completed Phase III trials in Argentina, Bahrain, Egypt, Morocco, Pakistan, Peru, and the United Arab
Emirates (UAE) with over 60,000 participants. BBIBP-CorV shares similar technology with CoronaVac
and BBV152, other inactivated virus vaccines for COVID-19.
 Peer-reviewed results published in JAMA of Phase III trials in United Arab Emirates and Bahrain
showed BBIBP-CorV 78.1% effective against symptomatic cases and 100% against severe cases (21
cases in vaccinated group vs. 95 cases in placebo group). In December 2020, the UAE previously
announced interim results showing 86% efficacy.

 Sinopharm COVID-19 vaccine
 On 7 May 2021, the World Health Organization approved the vaccine for use in COVAX.
 BBIBP-CorV is being used in vaccination campaigns by certain countries in Asia, Africa, South
America, and Europe. Sinopharm expects to produce one billion doses of BBIBP-CorV in 2021. By
May, Sinopharm had supplied 200 million doses.

 Moderna COVID 19 vaccine
 The Moderna COVID 19 vaccine, codenamed mRNA-1273, is a COVID-19 vaccine developed by
Moderna, the United States National Institute of Allergy and Infectious Diseases (NIAID) and the
Biomedical Advanced Research and Development Authority (BARDA). It is used in people aged 18
years and older to provide protection against infection by the SARS-CoV-2 virus. It is designed to be
administered as two 0.5 mL doses given by intramuscular injection at an interval of four weeks apart.

 It is an RNA vaccine composed of nucleoside-modified mRNA (modRNA) encoding
a spike protein of SARS-CoV-2, which is encapsulated in lipid nanoparticles.
 The Moderna COVID-19 vaccine is authorized for use at some level in 45 countries
including the United States, Canada, the European Union, the United Kingdom,
Israel, and Singapore.
 On 15 March 2021, Moderna's second COVID-19 vaccine (mRNA-1283) started
phase I clinical trials.

 Evidence of vaccine efficacy starts about two weeks after the first dose. High efficacy is achieved with
full immunization, two weeks after the second dose, and was evaluated at 94.1%: at the end of the
vaccine study that led to emergency authorization in the USA, there were eleven cases of COVID-19
in the vaccine group (out of 15,181 people) versus 185 cases in the placebo group (15,170 people).
 Only individuals aged 18 or older were studied. Studies are underway to gauge efficacy and safety in
children aged 0–11 (KidCOVE) and 12–17 (TeenCOVE).

 The most common adverse events were pain at the injection site, fatigue, headache,
myalgia (muscle pain), and arthralgia (joint pain).
 The US Centers for Disease Control and Prevention (CDC) has reported
anaphylaxis (a severe allergic reaction) in 2.5 cases per million doses administered
and has recommended a 15-minute observation period after injection.

 Storage
 The Moderna news followed preliminary results from the Pfizer-BioNTech vaccine candidate,
BNT162b2, with Moderna demonstrating similar efficacy, but requiring storage at the
temperature of a standard medical refrigerator of 2–8 °C (36–46 °F) for up to thirty days or −20
°C (−4 °F) for up to four months, whereas the Pfizer-BioNTech candidate requires ultracold
freezer storage between −80 and −60 °C (−112 and −76 °F). Low-income countries usually have
cold chain capacity for only standard refrigerator storage, not ultracold freezer storage. In
February 2021, the restrictions on the Pfizer vaccine were relaxed when the US Food and Drug
Administration (FDA) updated the emergency use authorization (EUA) to permit undiluted
frozen vials of the vaccine to be transported and stored at between −25 and −15 °C (−13 and 5
°F) for up to two weeks before use.

 Johnson & Johnson COVID-19 vaccine
 The Janssen or Johnson & Johnson COVID-19 vaccine, was developed by Janssen
Vaccines in Leiden, Netherlands, and its Belgian parent company Janssen
Pharmaceuticals,subsidiary of American company Johnson & Johnson.
 It is a viral vector vaccine based on a human adenovirus that has been modified to
contain the gene for making the spike protein of the SARS-CoV-2 virus that causes
COVID-19. The body's immune system responds to this spike protein to produce
antibodies. The vaccine requires only one dose and does not need to be stored
frozen.

Clinical trials for the vaccine were started in June 2020, with Phase III trials involving
around 43,000 people. On 29 January 2021, Janssen announced that 28 days after a
completed vaccination, the vaccine was 66% effective in a one-dose regimen in
preventing symptomatic COVID-19, with an 85% efficacy in preventing severe COVID-
19, and 100% efficacy in preventing hospitalization or death caused by the disease.
The vaccine has been granted an Emergency Use Authorization by the US Food and
Drug Administration and a conditional marketing authorisation by the European
Medicines Agency (EMA).

Characteristics
Unlike several of the other vaccines (such as the Oxford–AstraZeneca, Pfizer–
BioNTech, and Moderna vaccines), the Johnson & Johnson vaccine is administered as
a single dose instead of as two separate doses.
Unpunctured vials may be stored between 9 to 25 °C (48 to 77 °F) for up to twelve
hours, and it can remain viable for months in a standard refrigerator.

 Adverse effects
 The most common side effects are pain at the injection site, headache, tiredness, muscle
pain and nausea, affecting more than 1 in 10 people. Coughing, joint pain, fever, chills, redness,
and swelling at the injection site occurred in less than 1 in 10 people. Sneezing, tremor, throat
pain, rash, sweating, muscle weakness, pain in the arms and legs, backache, weakness, and
feeling generally unwell occurred in less than 1 in 100 people. Rare side effects (that occurred
in less than 1 in 1,000 people) are hypersensitivity (allergy) and itchy rash.

 Adverse effects
 Formation of blood clots in the blood vessels in combination with low levels of blood
platelets (known as Thrombosis with Thrombocytopenia Syndrome, or TTS) occurred in less
than 1 in 10,000 people one to two-weeks following vaccination. The CDC found TTS at "a rate
of about 7 per 1 million vaccinated women between 18 and 49 years old," and cautions that
"women younger than 50 years old should especially be aware of their increased risk for this
rare adverse event. There are other COVID-19 vaccines available for which this risk has not
been seen." In particular, "as of April 23, 2021, [TTS] has not been linked to the Pfizer-BioNTech
or Moderna COVID-19 vaccines after more than 210 million doses administered.

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