covishield vaccine

Covishield Vaccine efficiency, side effects and all other details

Covishield is one of the first available mRNA vaccine of coronavirus. It helps to build immunity against coronavirus infection. Although being one of the early available vaccines, Covishield vaccine also created different controversial issues. So here is a complete guide of covishield vaccine for people. Let’s go through it.

Image: Covishield Vaccination

Composition of Covishield Vaccine:

One recommended dose of Covishield vaccine should contain (0.5 ml) of covishield. One dose (0.5 ml) of covishield vaccine contains the following-

  • ChAdOx1  nCoV-19 coronavirus vaccine (Recombinant) 5X1010 viral particles (vp)
  • Recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 Spike (S) glycoprotein.
  • It is produced in genetically modified human embryonic kidney (HEK) 293 cells.
  • It contains genetically modified organisms (GMOs).

Here it is important to note that both Covishield (made by Serum Institute of India Pvt Ltd) and COVID-19 Vaccine AstraZeneca (made by AstraZeneca) are ChAdOx1 nCoV-19 coronavirus vaccines (Recombinant).

Covishield vaccine ingredients-

We all want to know the ingredients of the covishield vaccine. Here is a list of the covishield vaccine ingredients

L-Histidine, L-Histidine hydrochloride monohydrate, Magnesium chloride hexahydrate, Polysorbate 80, Ethanol, Sucrose, Sodium chloride, Disodium edetate dihydrate ( EDTA), Water for injection.

Covishield vaccine looks like-

  1. It is a solution for injection.
  2. The solution is colorless to slightly brown, clear to slightly opaque and particle-free with a pH of 6.6

Who can get Covishield Vaccine?

Covishield vaccine is indicated for active immunization of individuals who are older than 18 years for the prevention of covid 19.

Covishield is not advised to children or below 18 years. There are other vaccines available for kids and children. Choose one that is available in your region.

Covishield Vaccine dose:

The vaccine is given through the intramuscular (IM) route, preferably in the deltoid muscle in upper arm. Covishield vaccination course consists of two separate doses of 0.5 ml each.

The second dose should be taken between 4 to 6 weeks after the first dose. Although data from various countries suggest that one can take second dose of covishield vaccine (administration) up to 12 weeks after the first dose.

That’s why many national government like Indian Government proposed a guideline to take the second dose after 12-16 weeks from the first dose.

It is recommended that a person who is vaccinated with the first dose of covishield should complete the vaccination course with Covishield.

What if one miss second dose of covishield vaccine-

The second dose of covishield vaccine is a must after first dose covishield vaccination. But if one miss the second dose then it is best to consult with medical expert. Because depending on the individual cases, alternative actions can be taken.

How covishield vaccine works?

Covishield is a monovalent vaccine composed of a single recombinant, replication-deficient chimpanzee adenovirus(ChAdOx1) vector encoding the S glycoprotein of SARS-CoV-2. After the administration, the S glycoprotein of SARS-CoV-2 inside body exposes to stimulate neutralizing antibody and cellular immune responses against the S glycoprotein. This immune response will protect the individual in future if they get infected with coronavirus. This is the Mechanism of action of covishield.

Covishield vaccine efficiency-

As one of the early mRNA vaccine of the world, there are many controversies created against covishield. But overall the vaccine showing a good and effective result with no harm among people.

Accoding to the phase three clinical trial of covishield vaccine, the efficacy rate is 76% among symptomatic covid 19 patients. More interestingly, with covishield second dose in a 12 weeks gap the efficacy rate is 82%.

There is no prominent data available about the efficacy rate of covishield vaccine among those above 65 years of age. Upcoming times will show how much effectively covishield vaccine worked on aged people.

There is limited data available about the efficacy and safety of covishield in persons older than 65 years of age. There is no need for adjustment of dose for elderly persons above 65 years of age.

The safety and efficacy of covishield vaccine in children and those under 18 years old are not known yet. Trials are going on. There are other vaccines that are approved for children worldwide. Apparently, the available data of Covishield vaccine showing, it is 100% safe to use for adults as on December, 2021.

Covishield and Omicron:

There is no severity found for vaccinated people worldwide. So till 2021, omicron is a mild breakthrough infection for vaccinated people. Even for non vaccinated people it is showing mild symptoms. Apparently the available data of the omicron is showing it is highly infective though the fatal outcome is not clear.

But as experts saying it may turn to severe at anytime for non vaccinated people. Certainly there is high risk for non vaccinated people or people with partially vaccinated. So if one is partially vaccinated take precautionary measure.

When there is speculations from different sources that very soon a booster dose will be advised for omicron and similar mutant variants, WHO not confirmed it yet. In fact in an article of WHO they clearly mentioned that before officially confirming booster dose we need lot more detailed data.
In an official statement, Covishield official claimed that booster will not be helpful to prevent omicron variant.

According to some experts, Covaxin will work better than covishield. You can check the Covaxin vaccine and Covishield vaccine comparison before taking the final decision.

Who should not take covishield vaccine dose:

Yes, there are some people who are not advised to take covishield vaccine. The special cases are when you have some of the following conditions. In such specific conditions one needs to take special precautions. The conditions are the following


Just like other injectable vaccines, appropriate medical treatment and supervision should always be readily available in case of an anaphylactic reaction after administering the vaccine.

Concurrent illness

Covishield should not be administered in persons suffering from an acute severe febrile illness. But people with minor infections like a low-grade fever, cold, etc., should not delay vaccination.

Thrombocytopenia and coagulation disorders

Covishield is given by intramuscular route, so it should be given with caution in people who have thrombocytopenia (Low platelets count in blood), who have any coagulation disorder or are under anticoagulation therapy as bleeding or bruising may occur after intramuscular administration of covishield vaccine in these people.

Immunocompromised individuals

Enough data is not available if the covishield vaccine elicits the same response as normal immunocompetent (having strong immunity) persons, in persons with impaired immune responsiveness, such as persons under immunosuppressant therapy etc. Immunocompromised (having weak immunity) persons may have a relatively weaker immune response after vaccine administration. So efficiency of vaccine may differ.

Covishield vaccine efficacy:

The efficacy (effectiveness) of covishield vaccine is already established. It is shown that, all the different mutant variants are not fatal for those who completed the covishield vaccine two doses.

But it is note to follow that vaccine will not prevent to get affected by covid 19, it will only prevent from fatal outcomes of coronavirus. So even after taking vaccine, one can get breakthrough symptoms (that is covid symptom after covid 19 vaccination) which are really mild. We recommend to follow all the covid protocols and if you have covid symptoms follow the precautionary measures.

Covishield vaccine protection duration-

This is not established to date. You may get a protective immune response 4 weeks after the second dose of the covishield vaccine. Various research reports indicate that vaccine may protect you for up to six months. More research is needed in this regard.

Like other vaccines,covishield also may not protect all individuals who received the vaccine. As our immunity varies from person to person, so ultimately how much degree of protection it will give will also vary. Because the degree of protection will depend on how well our body able to produce the antibody as well as how well our memory B cells will be able to hold the memory.

So in future, if this same coronavirus can infect us, our immune system through its memory can produce antibody and will fight for it. So ultimate immune response will vary from person to person, so the level of protection will also vary.

Interchangeability of different vaccines:

A person who has taken the first dose of the covishield vaccine should take the second dose only with the covishield vaccine. You should not take different other covid 19 vaccines in your second dose.

Covishield vaccine and pregnancy:

There is not enough available data that the covishield vaccine is safe for pregnant women who want to conceive or for breastfeed mothers.

Covishield vaccine should be given to pregnant women only when the potential benefits are seem to be much higher than any potential risk for the mother and the baby of the womb.

It is not known to date that whether covishield vaccine is excreted in human milk.

Restrictions after covishield vaccination:

There is no as such restrictions after covishield vaccination. Covishield vaccine has no or negligible effect on driving and using machines. But some of the adverse reactions after taking this vaccine may temporarily (for few days) affect the ability to drive or use machines. So it varies from person to person.

Overdose of covishield vaccine:

There is no specific treatment for an overdose with the covishield vaccine. If an overdose occurs in a person, the person should be monitored carefully by a healthcare provider and should be given symptomatic treatment as required.

Frequently Asked Questions:

We know there are lots of questions in your mind regarding your covid 19 vaccines. So we suggest to go through our frequently asked questions about covid 19 vaccine and Common questions asked about Covishield.


  1. Serum Institute, India
  2. Ministry of Health and Family Welfare
  3. CDC study report
  4. WHO Report
  5. WHO Official Website
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