The Hindu Explains | How effective are the two COVID-19 vaccines rolled out in India, and are there concerns about safety?

What should be done in case of side effects? Why is an effective and safe vaccine important?

Updated - March 21, 2021 07:20 pm IST

Published - January 24, 2021 02:30 am IST

A nurse fills a dose of Covishield vaccine in an injection to administer it to a frontline worker at Rajawadi hospital in Mumbai on January 16, 2021.

A nurse fills a dose of Covishield vaccine in an injection to administer it to a frontline worker at Rajawadi hospital in Mumbai on January 16, 2021.

The story so far: Two COVID-19 vaccines, Covaxin and Covishield, after being granted emergency use authorisation , were rolled out on January 16 across India to inoculate 3 crore healthcare and frontline workers in the first phase of the vaccination drive. Both the vaccines have been manufactured in India. While Covaxin is produced under a collaboration between Bharat Biotech and the Indian Council of Medical Research, Covishield has been developed by AstraZeneca and Oxford University with the Serum Institute of India conducting clinical trials of the vaccine in the country and also manufacturing the vaccine for India and low- and middle-income countries.

What are the known side effects of the two vaccines?

Covishield is made of a weakened and modified version of adenovirus (a common cold virus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein. After vaccination, the surface spike protein is produced, priming the immune system to attack the SARS-CoV-2 virus if it later infects the body.

Also read | Covaxin not to be used in cases of allergy, fever, poor immunity

Common side effects of the vaccine include tenderness, pain, redness, itching, swelling or bruising, fatigue, chills or feeling feverish, headache, nausea, joint pain or muscle ache, a lump at the injection site, fever, vomiting and flu-like symptoms, such as high temperature, sore throat, runny nose, cough and chills. Feeling dizzy, decreased appetite, abdominal pain, enlarged lymph nodes, excessive sweating, itchy skin or rash are the uncommon side effects of the vaccines. Apart from this, “serious and unexpected side effects may occur”, the SII has stated.


Bharat Biotech in its fact sheet notes that besides the listed side effects, Covaxin, in rare cases, can also cause a severe allergic reaction. “Although rare, signs of this include difficulty in breathing, swelling of your face and throat, a fast heart rate, rash all over the body and dizziness and weakness,” the company said.

Who should not be taking the vaccines?

Cross-use of either of the vaccines is not permitted and the vaccines are contraindicated for pregnant and lactating women .

Also read | Vaccine dilemma — to take or not to take Covaxin

Besides this, Covaxin should not be given to those who are immunocompromised or are on medication for the same, individuals with a history of allergies, those who have a fever, a bleeding disorder or are on a blood thinner, as per information released by the company. Similarly, Covishield, which is allowed for restricted use in emergency situations in individuals 18 years of age and older, should not be used by people who have had a severe allergic reaction to any ingredient of the vaccine or had a severe allergic reaction after a previous dose. Beneficiaries are also to tell medical staff about any bleeding disorder, an immunocompromised medical condition, and the medication for that. Healthcare workers should also be informed if the beneficiary has got another vaccine shot.

Why is an effective and safe vaccine important?

The development of safe, effective, affordable, and deployable vaccines against COVID-19 is paramount for tackling the COVID-19 crisis and re-establishing normality.

Also read | Covaxin recipients asked to sign consent form on ‘clinical trial mode’

“We report on the first clinical efficacy results of ChAdOx1 nCoV-19 [Covishield] in a pooled analysis of phase 2/3 trials in the UK and Brazil, and safety data from more than 20,000 participants enrolled across four clinical trials in the UK, Brazil, and South Africa. ChAdOx1 nCoV-19 has an acceptable safety profile and is efficacious against symptomatic COVID-19, with no hospital admissions or severe cases reported in the ChAdOx1 nCoV-19 arm. The vaccine can be stored and distributed at 2–8°C, making it particularly suitable for global distribution,” noted an interim study published in TheLancet recently.

Similarly, Bharat Biotech, in its fact sheet released this week, said in phase 1 and 2 clinical trials, Covaxin has demonstrated the ability to produce antibodies against COVID-19. However, the clinical efficacy of the vaccine is yet to be established and it is still being studied in phase 3 clinical trials, said the company.

Both the vaccine makers note that receiving the vaccine does not mean that other precautions against COVID-19 need not be followed.

Also read | Indian scientists divided over nod for Covaxin

What should be done in case of side effects?

While the Health Ministry has claimed that so far, there have been no serious or severe reactions after vaccination, it is advised that you call a healthcare provider if you have any side effects that bother you or which do not go away. The Ministry says that if one experiences a severe allergic reaction, they must go to the nearest hospital. The Health Ministry has now also updated its Co-WIN system for “enhanced safety of the beneficiaries”. It said the enhanced system allows tagging of contraindications in the vaccinator module. “The improved module also allows the creation of more session sites and change in site location. It also facilitates the planning and scheduling of the sessions for the entire week,” added the Ministry.

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