Covaxin or Covishield? Take a look at our guide to help you choose a COVID-19 vaccine

Healthcare workers at the state store pack the vaccine developed by Oxford/AstraZeneca into a box before being transported to a regional vaccine store, during the coronavirus disease (COVID-19) pandemic, in Bhubaneswar, January 13. (Image: Reuters)

Healthcare workers at the state store pack the vaccine developed by Oxford/AstraZeneca into a box before being transported to a regional vaccine store, during the coronavirus disease (COVID-19) pandemic, in Bhubaneswar, January 13. (Image: Reuters)

With 24.3 million Indians inoculated once, the important factors to determine the efficacy of a jab is to see how widely it is used in developed economies and the endorsement it receives from the WHO. Here Covishield, has the edge

Beginning March, India has extended COVID-19 vaccination to include people above 60 years, and those who are 45-plus with co-morbidities.

So far 24.3 million people in the country have got at least one dose of COVID-19 vaccine.

There isn’t much choice for people in India between Serum Institute of India’s (SII) Covishield and Bharat Biotech’s Covaxin. Covishield, which has been widely used for inoculation, is manufactured and distributed by SII with a license from AstraZeneca-Oxford University.

Here is a guide to help you choose the vaccine.


One of the important factors to determine the efficacy of a vaccine is to see how widely it is used across the world, especially in developed economies and the endorsement it receives from the World Health Organization (WHO).

Here Covishield, which is the AstraZeneca-Oxford University COVID-19 vaccine version, has an edge. The jab has been granted conditional marketing authorization or emergency use authorization (EUA) in more than 50 countries, including India, UK, EU and Canada.

It recently got Emergency Use Listing by the WHO, which accelerates its access in up to 142 countries through the COVAX Facility.

COVAX Facility, the abbreviation for COVID-19 Vaccines Global Access, is a global initiative aimed at equitable access to COVID-19 vaccines led by UNICEF, Gavi, the Vaccine Alliance, WHO and the Coalition for Epidemic Preparedness Innovations, among other organizations.

Bharat Biotech is approved in India for restricted emergency use under clinical trial mode. The company will soon be exporting the vaccine to Brazil, Mexico and other countries.

Also read: Rich nations resist push from developing countries, including India, to boost vaccine production


The vaccine platform plays a key role. COVID-19 vaccines are made using four platforms – inoculations based on genetic material like mRNA, viral vector, protein subunit and whole virion.

While whole virion and protein subunit vaccines are old platforms, mRNA is a novel platform that came to fore during COVID-19 pandemic. Viral vector vaccines have been used for developing Ebola immunization.

Covaxin is based on an inactivated whole virion platform, which essentially uses an inactivated SARS-CoV-2 virus as a vaccine. The inactivated poliovirus (IPV) vaccine has been used extensively on children for polio jabs, ensuring that the technology is safe and well tolerated. Covaxin has the edge as it is based on a simple and well established platform.

Efficacy data— what does it tell about the vaccines?

Vaccine development that normally takes 5-10 years has now been fast tracked to 12-18 months due to the urgency triggered by the pandemic. Most shots are given emergency use approval, as the data is limited.

Covishield, which has an efficacy of 70.4 percent, on an average, in preventing COVID-19, as per the interim analysis of its late-stage clinical trials conducted in the UK and Brazil.

In Brazil, two full doses of the vaccine were given one month apart, involving 8,895 participants and it appeared to be 62 percent effective.

The primary outcome of the efficacy trial is to measure how effective the vaccines are in reducing the symptomatic disease.

SII conducted a bridge study in India on 1,600 volunteers using the same dosing regimen as Brazil. The bridge study, submitted to Drugs Controller General of India (DGCI), is not meant to measure efficacy; it’s used to find out safety and immunogenicity in the local population.

A recent study published in British medical journal Lancet pointed out that vaccine efficacy after the second dose was even higher at 81·3 percent in those with a dosing interval of 12 weeks or more.

In India the vaccine needs to be taken at an interval of four weeks or 28 days.

The phase-3 trial in the US is ongoing. In total AstraZeneca-Oxford University has enrolled 60,000 participants globally. AstraZeneca-Oxford have published the interim analysis of this trial, which was published in Lancet in December last year.

Bharat Biotech’s Covaxin demonstrated 81 percent interim efficacy in preventing COVID-19 in those without prior infection after the second dose.

The first interim analysis is based on 43 cases, of which 36 cases of COVID-19 were observed in the placebo group versus 7 cases observed in the Covaxin group, resulting in a point estimate vaccine efficacy of 80.6 percent.

Bharat Biotech said it would share the second interim analysis data based on 87 cases. The final analysis is planned for 130 cases in the coming weeks. To be sure, data from those analyses will give a more accurate picture on the efficacy of the vaccine.

The Hyderabad-based Indian company conducted its clinical trial in India involving 25,800 subjects in Phase-3, the largest ever in this country.

Said Amar Jesani, a consultant on bioethics and public health: “the number of publications of data in reputed scientific journals also raises the confidence on vaccines.”

He also expects vaccine developers to publish raw clinical trial data to allow for independent reviews.

Do vaccines prevent infection and transmission?

No substantive data is available at the moment, to prove whether the COVID-19 vaccines prevent human-to-human transmission of the disease. WHO says that even if one is vaccinated, public health measures such as masking, physical distancing, hand washing, respiratory and cough hygiene, avoiding crowds, and ensuring good ventilation needs to be followed.

Will these vaccines help in preventing severe COVID-19, hospitalization and death?

Clinical trial data from most other COVID-19 vaccines indicate that they are effective in preventing hospitalization and death. There isn’t much data available on Covaxin on this front.

The interim analysis from the clinical trial data of AstraZeneca-Oxford is based on cases occurring within approximately four months of follow-up in 11,636 participants, the majority of whom were aged 18–55 years

No COVID-19-related hospital admissions occurred in AstraZeneca-Oxford vaccine recipients, whereas ten (two of which were severe) occurred in the control groups. Experts, however, believe that more data needs to be generated before they arrive at a definitive conclusion.

Public Health England (PHE), an executive agency of the Department of Health and Social Care in the UK, has submitted a pre-print of a real-world study that shows that Oxford-AstraZeneca vaccine is highly effective in reducing severe COVID-19 infections among older people aged 70 and over.

Since January, protection against symptomatic COVID, four weeks after the first dose, ranged between 60 and 73 percent for the AstraZeneca-Oxford vaccine. It scored better than Pfizer’s 57 and 61 percent for one dose.

Dr. Debashis Das, a Mumbai-based diabetologist told Moneycontrol that he advises his patients with co-morbidities and those who are elderly, to take vaccines.”Even if the vaccine gives 20-30 percent protection, it will be beneficial,” he said.

On new variants

Both the vaccines have been found to be effective against the UK variant of coronavirus. While AstraZeneca-Oxford vaccine is discovered to have only 10 percent efficacy against South African variant N501Y, Covaxin is yet to be tested on this strain.

In theory, inactivated vaccines, such as Covaxin, provide broader protection against mutating variants, as they are based on the whole virus. AstraZeneca said it is updating its COVID-19 vaccine to make it effective against new variants.

Who is not recommended for the vaccine?

People with a history of severe allergic reaction to any component of the vaccine are advised not to take it, according to WHO.

What about pregnant women?

If a person is pregnant, plans to become pregnant or is breastfeeding, she should inform the healthcare provider before taking the jab. This is WHO’s advice to pregnant women at high risk of exposure to COVID-19 or those who have comorbidities, which add to their risk of severe disease.

What about children?

The COVID-19 vaccines in India are approved for 18 years and above. So, clinical trials will have to be conducted to ascertain whether these vaccines are safe on children and teenagers.

Vaccine maker’s reputation

Experts say the track record or reputation of the vaccine producer makes all the difference. “The first thing to look at is, who developed this vaccine, and what has been their history and track record in producing safe vaccines,” says Davinder Gill, entrepreneur, and former CEO of Hilleman Laboratories, which develops novel vaccines.

He believes a good track record will instill confidence that the vaccine has been properly tested in terms of safety and efficacy, as a lot rides on the reputation of the vaccine maker.

Both Serum Institute of India and Bharat Biotech are reputed companies with a long track record of manufacturing and supplying vaccines to the WHO.

What are the possible side-effects of the Covishield vaccine?

Very common side-effects include tenderness, pain, warmth, redness, itching, swelling, or bruising where the injection is given, generally feeling unwell, fatigue, chills, headache, nausea, and joint pains.

Some people have other side-effects such as vomiting, and flu-like symptoms such as high temperature, sore throat, running nose, cough, and chills.

The Phase-2 data published by Bharat Biotech’s Covaxin in Lancet says that the probability of experiencing a side effect was 10-12 percent or six times lower than other EUA vaccines.

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