Everything you need to know about Pfizer vaccine

Everything you need to know about Pfizer vaccine

Pfizer-BioNTech is a Lipid nanoparticle-formulated mRNA vaccine encoding the SARS COV-2 spike protein which is responsible for facilitating the entry of the virus into the cell. 

The Pfizer-BioNTech is Food and drug administration approved vaccine. It is authorized for Emergency use in COVID-19 pandemic and hence called Emergency use authorization (EUA) vaccine approved on 13 December 2020 to be used in an emergency for vaccination of the population against the COVID-19 virus.

Sputnik-V, a vaccine developed by Russia against the coronavirus disease (Covid-19), has been approved for emergency use in India by a group of in-house experts in the midst of the second wave of the pandemic. 

If the Drugs Controller General of India approves it, this will be the third Covid-19 vaccine used in India, following Covishield and Covaxin (DCGI).
Last week, Dr Reddy's Laboratories, a pharmaceutical firm located in Hyderabad, applied to the government for permission to use the vaccine in India. 
In September 2020, the Russian Direct Investment Fund (RDIF) collaborated with Dr. Reddy's to conduct Sputnik V clinical trials in India. 
According to the interim review of phase III clinical trials, which included data from 19,866 volunteers in Russia, the Russian vaccine has a 91.6 percent efficacy. 
According to the Sputnik-V website, the company is performing Phase III clinical trials in the UAE, India, Venezuela, and Belarus.
According to news agency PTI, RDIF partnered with Hyderabad-based Virchow Biotech Private Limited in March to manufacture up to 200 million doses of Sputnik V per year in India. 
It also partnered with Stelis Biopharma Pvt Ltd and Panacea Biotec in April to produce 200 million and 100 million Sputnik V doses per year in the region, respectively.

Mode of Action
Pfizer vaccine generates antibodies that block the entry of SARS COV-2 into the cells hence preventing the individual from disease.
1. Live virus is not present in mRNA vaccines so there is no risk of developing disease on a vaccinated individual.
2. mRNA vaccines do not interact with human DNA as it never enters the cell nucleus.

Dose and Dosage Regimen
0.3 ml Pfizer vaccine is administered intramuscularly in the deltoid muscle. It is 2 dose vaccine and the second dose is administered 21 days that is 3 weeks after the administration of the initial dose. A multi-dose vial contains 6 doses per vial. 

0.9% Sodium chloride normal saline is used as a diluent in vaccine and the new vial is used every time the vaccine is administered

1. If Individuals receiving the vaccine have an allergy to any other vaccine or injectable which can be intramuscular, intravenous, or subcutaneous.
2. If the individual receiving vaccine has an allergy to vaccine components or ingredients but the ingredient is unknown.
3. People who have contraindications for the Janssen COVID-19 vaccine.
4. Patients with moderate to severe acute illnesses should avoid vaccination.

Adverse Reactions

First dose

Clinical Trials
Pain at the injection site
Muscle pain 
Joint pain
Swelling at the injection site
Redness  at the injection site

Post authorization 
Anaphylaxis and other hypersensitivity reactions are seen in this phase 

Second dose: The intensity of side effects increases after second dose 

Severe pain at the injection site
Severe fatigue 
Severe headache 
Severe muscle pain 
Severe chills
Severe joint pain
Severe fever
Severe swelling at the injection site
Severe redness  at the injection site
Severe nausea
Severe malaise
Severe lymphadenopathy
Severe rashes 
Severe pruritus
Severe urticaria
Severe angioedema

Special Groups 

1. Elderly and pediatric population
Older age groups and pediatric population can have any type of serious effect on vaccine administration as safety data is not available for these populations hence vaccination should be done cautiously.

2. Hypersensitivity reaction or Anaphylaxis
Individuals who are allergic to the vaccine or its ingredients should not get vaccinated as it could become serious.

3. Comorbidities 
The patients who have any type of co-morbid disease like liver, kidney or heart disease, etc have a greater risk of development of adverse reactions so they should be given extra care after vaccination. 

4. Pregnancy and Breastfeeding 
The vaccine can have severe adverse reactions like abnormalities in newborns and can be harmful to the fetus so vaccination should be prohibited in pregnancy and breastfeeding as safety data is not available.

5. Concomitant vaccines
The safety and efficacy of Pfizer with other vaccines are not studied in the population so the two vaccines should not be administered simultaneously.

Efficacy of Pfizer vaccine

MoH recently studied that after the second dose of vaccine the immunity grows stronger as it produces antibodies against Covid-19 infection and is 97% efficacious in the prevention of symptomatic disease and death.

How long does the Pfizer vaccine last?

A study on Pfizer revealed that the Pfizer vaccine was 91.3% effective on 927 patients with the symptomatic disease which was measured seven days to 6 months after the second dose. The vaccine was proved to be 100% effective against severe disease according to the U.S. Centers for Disease Control and Prevention (CDC) while according to U.S. Food and Drug Administration (FDA) it is 95.3% efficacious against Covis-19 infection.

Effect of Pfizer- BioNTech on Variants

When the virus keeps on circulates or spreads in a large population the virus DNA changes to adapt to variable conditions of the worldwide population and this process is called mutation and the new virus is called variant. Due to this mutation, the genome of the virus changes and it becomes more resistant to the existing medications or vaccines and hence the efficacy of the Pfizer vaccine can decrease due to resistance or it can become completely ineffective as the efficacy and safety of the vaccine on new variants are not fully established.  

Concluding note

Pfizer- BioNTech vaccine is approved for the emergency to prevent COVID-19 disease and have different indications and contraindications like in case of allergy, pediatric, elderly groups, etc and hence can have different types of adverse reactions or side effects which can be fatal to the individual receiving vaccine, therefore, the vaccine should be administered cautiously in the vulnerable groups. The Health care workers are required to report the side effects or adverse events occurring due to vaccine to protect the patients from serious or fatal conditions