Covaxin vs Covishield – A Detailed Comparison – Efficiency, Side Effects and Much More!

Following AstraZeneca’s acknowledgment of rare side effects associated with its COVID-19 vaccine (branded as Covishield in India), recent attention has also turned toward Bharat Biotech’s Covaxin, another widely administered COVID-19 vaccine in India during the pandemic.

When comparing Covaxin and Covishield, both vaccines have been associated with commonly reported, mild side effects such as fever, fatigue, chills, and nausea—symptoms that typically resolve on their own within a few days.

In rare cases, Covishield has been linked to blood clotting disorders and decreased platelet counts, as well as reports of upper respiratory infections and menstrual irregularities. These rare side effects have been studied extensively in various global research initiatives.

To address public concerns, Bharat Biotech reaffirmed the safety profile of Covaxin, highlighting its extensive clinical testing and post-market surveillance data.

A recent study conducted at Banaras Hindu University (BHU) followed Covaxin recipients over a one-year period. The study found that approximately one-third of participants experienced what are classified as Adverse Events of Special Interest (AESI). These included mild to moderate symptoms, and in about 1% of cases, neurological events such as stroke or nerve-related issues were reported. Upper respiratory symptoms were also observed during follow-ups.

There were also indications that individuals who received three or more doses might have experienced a slightly increased incidence of such events, although this area still requires more rigorous research and analysis.

Despite these findings, health experts maintain that the overall benefits of COVID-19 vaccination significantly outweigh the risks, particularly in preventing severe illness, hospitalization, and death. Continuous monitoring and research are ongoing to ensure vaccine safety and address emerging concerns.

What are Covaxin and Covishield?

Both Covaxin and Covishield were key vaccines used in India’s COVID-19 immunization campaign, rolled out under emergency use authorization in early 2021. Here’s an overview of each:

a) Covaxin

Covaxin is an inactivated virus-based COVID-19 vaccine developed by Bharat Biotech in partnership with the Indian Council of Medical Research (ICMR) and the National Institute of Virology (NIV). This vaccine uses a traditional platform that involves a killed version of the SARS-CoV-2 virus to trigger an immune response without causing illness. Covaxin began distribution in January 2021, and it has since been administered to millions across India.

b) Covishield

Covishield is the Indian-manufactured version of the Oxford-AstraZeneca vaccine, produced by the Serum Institute of India. It is a viral vector vaccine that uses a modified, replication-deficient chimpanzee adenovirus to deliver genetic instructions for building immunity against the virus. Covishield was also rolled out in January 2021 under emergency authorization and became one of the most widely used vaccines during India’s COVID-19 vaccination drive.

Covaxin vs Covishield: What Are the Key Differences?

Both Covaxin and Covishield played major roles in India’s COVID-19 vaccination program. While both are effective in reducing the risk of severe illness and hospitalization due to COVID-19, they differ in terms of technology, composition, and dosing schedules.

1. Vaccine Type

• Covaxin is an inactivated virus vaccine, meaning it contains a killed version of the virus to safely trigger an immune response.
  
• Covishield is a viral vector vaccine, which uses a harmless, non-replicating chimpanzee adenovirus to deliver genetic material that helps the body build immunity.
  

2. Storage Requirements

Both vaccines are stable at standard refrigeration temperatures of 2°C to 8°C, making them compatible with existing cold chain infrastructure across healthcare systems.

3. Efficacy Rates

• Covaxin demonstrated approximately 78% efficacy in phase III clinical trials in preventing symptomatic COVID-19.
  
• Covishield showed an average efficacy of about 70% after the first dose, which may increase to around 90% with the second dose, depending on the dosing interval.
  

4. Dosing Schedule

• Covaxin: Two doses are administered 28 days apart.
  
• Covishield: Two doses with a gap of 4 to 12 weeks, with longer intervals associated with better immune response.
  

At a Glance: Comparison Table

Which One Is Better?

There is no definitive “better” vaccine—both have proven effective in reducing severe disease and hospitalisations. The choice between the two often depends on availability, individual health conditions, and medical advice. It’s always best to consult with a healthcare provider before deciding on any vaccination.

Type of Vaccines

Vaccines are generally classified into six main categories based on how they stimulate the immune system:

1. Inactivated or Killed Vaccines
   These vaccines contain viruses or bacteria that have been killed or inactivated so they cannot cause disease. They help the immune system recognize the pathogen without risking infection. Examples include Covaxin (COVID-19) and seasonal influenza vaccines.
   
2. Viral Vector Vaccines
   These use a harmless virus (different from the target virus) to deliver genetic instructions to cells, prompting them to produce a protein that triggers an immune response. Examples include Covishield (COVID-19) and the Johnson & Johnson COVID-19 vaccine.
   
3. Live Attenuated Vaccines
   These vaccines contain weakened forms of the virus or bacteria that replicate in the body without causing illness, stimulating strong immunity. The MMR vaccine (measles, mumps, rubella) is a common example.
   
4. Subunit, Recombinant, Polysaccharide, and Conjugate Vaccines
   These use specific parts of the pathogen, such as proteins or sugars, to elicit an immune response without exposing the body to the whole virus or bacteria. The HPV vaccine and hepatitis B vaccine belong to this group.
   
5. Toxoid Vaccines
   These vaccines use inactivated toxins produced by bacteria to build immunity against diseases caused by those toxins. Examples include the tetanus and diphtheria vaccines.
   
6. mRNA Vaccines
   These contain messenger RNA that instructs cells to produce a protein similar to one from the virus, which then triggers an immune response. The Pfizer-BioNTech and Moderna COVID-19 vaccines use this technology.

Also Read- The Role of The Pharmaceutical Industry in Healthcare

Vaccine Dosage Schedule

Covaxin is given in two doses, with the second dose administered 28 days after the first.

Covishield also requires two doses, but the recommended interval between doses ranges from 4 to 12 weeks. Research indicates that a longer gap between the two doses may enhance the vaccine’s effectiveness.

Common Side Effects of Covaxin and Covishield

Both Covaxin and Covishield vaccines may cause mild to moderate side effects, which generally resolve on their own within a few days.

Covaxin common side effects include:

• Pain, swelling, or redness at the injection site
  
• Fever
  
• Fatigue
  
• Headache
  
• Nausea
  

Covishield commonly reported side effects include:

• Pain and tenderness at the injection site
  
• Swelling at the injection site
  
• Fatigue
  
• Fever
  
• Chills
  
• Headache
  
• Nausea
  

These reactions are typical signs that the body is building protection and are usually short-lived. If any symptoms persist or worsen, it is advisable to consult a healthcare professional.

Age Eligibility for Covaxin and Covishield

Both Covaxin and Covishield vaccines were initially authorized for use in adults aged 18 years and older. Over time, regulatory approvals have expanded to include older adolescents as well. For the most current age eligibility guidelines, it is important to refer to updates from India’s National COVID Vaccination Program.

Key Takeaway

Covaxin and Covishield have been essential in India’s fight against COVID-19. Although they differ in their vaccine technology and dosing schedules, both vaccines provide strong protection against the virus. Understanding these differences can help individuals make informed vaccination decisions. Always seek personalized advice from a healthcare professional regarding vaccination.

Expert Quote

“Both Covishield and Covaxin have been thoroughly tested through clinical trials and have been widely administered, showing strong safety records and effective protection against COVID-19. Although they use different technologies, the key to controlling the pandemic and preventing severe disease is ensuring broad vaccination coverage. It is important for individuals to consult healthcare professionals to select the vaccine that best fits their personal health conditions and requirements.”

-Dr. Sachin Singh

Frequently Asked Questions (FAQs)

References

• Serum Institute of India Pvt Ltd. (n.d.). COVISHIELD FAQs: COVID‑19 vaccine. Retrieved June 2025, from https://www.seruminstitute.com/health_faq_covishield.php
• Bharat Biotech International Limited. (n.d.). COVAXIN – India’s first indigenous COVID‑19 vaccine. Retrieved June 2025, from https://www.bharatbiotech.com/covaxin.html
• Centers for Disease Control and Prevention. (2023). Understanding COVID-19 vaccines. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/expect.html
• National Institutes of Health. (2022). COVID-19 vaccines: What you need to know. https://www.nih.gov/health-information/coronavirus/your-health-covid-19/covid-19-vaccines
• U.S. Food and Drug Administration. (2023). COVID-19 vaccines. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/covid-19-vaccines